Section 2: SHEEP

Sheep Questions

CASE 2.1 During autumn three of 120 7-month-old unvaccinated Suffolk-cross lambs have been found dead over the past 4 days. Some of the lambs had been noted to be very dull and depressed with foul smelling diarrhoea for 12-24 hours but died despite treatment with an antibiotic.

1 What common problems could cause sudden death in these weaned unvaccinated lambs (most likely first)?

2 How could you confirm your provisional diagnosis?

3 What treatments would you consider?

4 What control measures would you recommend?

CASE 2.2 A 3-day-old Suffolk­cross male lamb presents with increasing abdominal distension, mild colic and frequent tenesmus (2.2a). The lamb is bright and alert but has stopped sucking its dam.

1 What conditions would you consider (most likely first)?

2 What action would you take?

CASE 2.3 In summer, you are presented with a ewe with multiple 1-3 cm diameter subcutaneous abscesses affecting the cheeks. These abscesses are surrounding by areas of hair loss and fistulated to the skin surface (2.3). The submandibular lymph nodes are enlarged. The sheep has been grazing rough pasture containing gorse and other spiky plants.

1 What common problems would you consider (most likely first)?

2 Are there any consequences to this infection?

3 How is the diagnosis confirmed?

4 What treatment(s) are necessary?

CASE 2.4 A 5-year-old ewe presents with a history of chronic weight loss (BCS 1.5/5); the remainder of sheep in the group are within a range of from 3/5 to 3.5/5.

1 What conditions would you consider?

2 What further tests would you undertake?

3 What is your diagnosis, and what treatment would you administer?

4 What is the likely cause?

CASE 2.5 During autumn, while selecting ewes to retain for the next breeding season, a client finds several young ewes to be in very poor body condition compared with normal sheep (2.5a; affected sheep on left, BCS 1.5/5; normal ewe on right, BCS 4/5). The fleece is also open and of poorer quality. The rectal temperature of the affected

sheep is normal and there is no evidence of diarrhoea.

1 What is your provisional diagnosis (most likely first)?

2 What tests would you undertake?

3 What action would you recommend?

4 What control measures could be adopted?

CASE 2.6 In winter a sheep farmer receives a report of ‘pneumonia’ (2.6) affecting a batch of 20 9-month-old lambs sent to a local slaughter plant. Your client is surprised by this comment because the lambs have been growing well with no mortality in the group over the past 2 months. The lambs were housed 10 weeks ago and are fed ad-libitum concentrates. The lambs were vaccinated against clostridial disease at 4 and 5 months old but not against Pasteurella pneumonia. The lambs were last treated with an anthelmintic in September, 1 month before housing. There is a bout of coughing whenever the lambs are disturbed but they appear bright and alert.

Examination of three lambs with an elevated respiratory rate (60 breaths per minute) reveals normal rectal temperatures (39.2-39.6° C [102.6-103.3°F]). None of the lambs has a mucopurulent nasal discharge.

1 What conditions would you

suspect (most likely first)?

2 What treatments would you administer?

3 What advice would you give?

CASE 2.7 During lambing time you are presented with a 5-day-old Texel lamb with sudden-onset tetraparesis (2.7a); the lamb had been normal for the first 4 days of its life. Four similarly affected lambs have died in the past week. The lamb's rectal temperature is normal. There are no palpable joint swellings and no swollen lymph nodes. There is low head carriage, evidence of cervical pain and gentle manipulation of the neck is resented. The reflex arcs are increased in all four legs. The umbilical stump is dry and brittle.

1 What is your diagnosis (most likely first)?

2 How could you confirm your diagnosis?

3 What treatments would you administer?

4 What preventive measures could be adopted?

CASE 2.8 You are presented with an emaciated 4-year-old Scottish Blackface ewe with a pendulous abdomen. The fleece is open and of poor quality. Rectal temperature is normal. The eyes appear sunken, which is thought to be largely due to the absence of intraorbital fat. Mucous membranes appear pale. There is no evidence of diarrhoea. The farmer reports that this is a common presentation on his farm and accounts for approximately 3-5% annual mortality in his flock. This sonogram (2.8a) is obtained on transabdominal ultrasound examination.

1 Interpret the important sonographic features.

2 What is your provisional diagnosis (most likely first)?

3 What further tests would you recommend?

4 What action would you take?

CASE 2.9 A new farm manager has taken over on a large Scottish highland estate and has experienced annual ewe mortality in excess of 12% in a 2,400 ewe flock, with losses occurring throughout the year.

1 How would you interpret the necropsy results?

2 What advice would you offer?

CASE 2.10 You are presented with two 15-month-old Texel rams who display frequent proprioceptive deficits and stumbling on the fore legs, particularly when forced to trot (2.10a, b). There is obvious hindleg ataxia and weakness, and dysmetria of the fore legs. These signs were first noted 6 months ago. Hopping deficits are present in all four legs. Withdrawal reflexes are exaggerated in the hind and fore legs. Sometimes the sheep collapse when handled. When placed in lateral recumbency they have prominent extensor tone of the hindlegs. Hyperreflexia with clonus and crossed extensor reflexes are also present in the hindlegs.

1 What conditions would you consider?

2 What further tests could be undertaken?

3 What actions/treatments would you recommend?

4 What control measures could be taken?

CASE 2.11 You are presented with an 8-month-old fattening lamb that shows multiple bilateral deficits of cranial nerves (CNs) III, V and VII (2.11a); assessment of the menace response is considered unreliable. The lamb is ataxic and has a bradycardia of 40 beats per minute. There is a bilateral mucopurulent nasal discharge.

1 What conditions would you consider?

2 What is the cause of this condition?

3 What treatment would you administer?

4 What is the prognosis for this lamb?

CASE 2.12 You are presented with a 5-month-old Suffolk-cross lamb that has been unable to bear weight on the fore legs (2.12a) for approximately 1 week. The lamb appeared normal for the first 4 months of life. There are no foot lesions, palpable joint swellings or swollen prescapular lymph nodes. There are lower motor neuron signs to the fore legs, with reduced reflexes and flaccid paralysis. There are upper motor neuron signs to the hindlegs, with increased reflexes and spastic paralysis.

1 Where is the probable site of the lesion?

2 What type of lesion would you suspect (most likely first)?

3 What further investigations could be undertaken?

4 What prognosis would you offer?

CASE 2.13 You are presented with a dystocia where the lamb’s head is presented through the vulva but both fore legs are retained alongside the chest (‘hung lamb’; 2.13a).

1 What action would you take?

CASE 2.14 During late winter a sheep farmer reports sudden-onset blindness affecting six of 600 ewes 4 weeks before lambing. The ewes are housed and fed ad-libitum grass silage and 350 g of concentrates per head per day. Four ewes are carrying twins, one ewe a singleton and one ewe is barren. The sheep are hyperaesthetic to sound and touch and are readily startled (2.14a). Appetite remains good. Clinical examination reveals bilateral absence of menace and pupillary light responses (2.14b). Ophthalmic examination reveals slightly narrowed retinal vessels and mild displacement of these vessels at the optic disc. The sheep had been treated for liver fluke 1 week previously and vaccinated against clostridial diseases.

1 What conditions would you consider?

2 What treatment would you administer?

3 What is this significance of this outbreak?

CASE 2.15 You are asked to comment on a recently purchased Texel ram that presents with large, non-painful, soft swellings over the dorsal aspect of both carpal joints (2.15a). The ram is not lame. The prescapular lymph nodes are normal sized. There is no pain on careful manipulation of the carpus. Rectal temperature is normal and the ram has a good appetite.

1 What conditions would you consider (most likely first)?

2 What further examinations would you take?

3 What advice would you offer?

CASE 2.16 A 2-crop ewe at pasture with 1-month-old twin lambs is found isolated from the remainder of the flock. The ewe appears lame and drags the right hindleg. The ewe is profoundly depressed with toxic mucous membranes. Rectal temperature is elevated (41.2°C [106.1°F]). Heart rate is increased above 130 beats per minute. Respiratory rate is increased to 45 breaths per minute. There are no ruminal sounds. Examination of the udder reveals extensive gangrenous mastitis of the right gland (2.16a), with subcutaneous oedema extending along the ventral abdominal wall to the brisket.

1 What pathogens could be involved?

2 What is the prognosis?

3 What action would you take?

4 What control measures could be adopted?

CASE 2.17 An aged Suffolk ram was euthanased on a Scottish lowland farm because of poor condition. In addition to severe molar dentition problems identified at postmortem examination, a 6 cm diameter inspissated abscess was noted in the mediastinal lymph node (2.17).

1 What is your diagnosis?

2 What action would you take?

3 What control measures should be adopted in this flock?

CASE 2.18 Two months after weaning a farmer complains of poor growth rates in 7-month-old lambs. The lambs are in poor condition with an open fleece and faecal staining of the perineum and tail (2.18a). The lambs have been grazing ‘safe pasture’ since weaning 6 weeks earlier. They were treated with monepantel (Group 4) before moving onto clean grazing; 10% of lambs were left undosed to maintain an ‘in refugia’ population.

1 What conditions would you consider (most likely first)?

2 How would you investigate this problem?

3 What treatment would you administer?

4 How would you prevent this problem recurring next year

CASE 2.19 During April a client complains of diarrhoea affecting several 3-6-week-old orphan Suffolk­cross lambs (2.19a) reared indoors. The lambs are reared on an automatic milk dispenser with an ad-libitum 18% crude protein concentrate. The younger lambs are more severely affected, with considerable faecal staining of the tail and perineum. There is frequent tenesmus, with passage of small quantities of fluid faeces containing a large amount of mucus and flecks of fresh blood.

1 What common problems would you consider (most likely first)

2 How could you confirm your provisional diagnosis?

3 What treatment would you administer?

CASE 2.20 Severe lameness is reported affecting 25 of a group of 120 6-month- old weaned lambs at pasture during late autumn. Typically, only one claw of one foot is affected, where there is separation of the hoof capsule around the entire circumference of the coronary band. There is loss of hair extending for 2-3 cm proximal to the coronary band (2.20a).

1 What conditions would you consider?

2 What is the likely cause?

3 What action would you take?

4 How could this condition be prevented?

CASE 2.21 Describe the method you would use to collect CSF from an obtunded sheep.

CASE 2.22 During winter you are presented with an obtunded Texel ram from a group of 16 Texel and Suffolk rams. Two Texel rams have presented with similar clinical signs over the past 10 days and have died despite antibiotic treatment by the farmer. The rams have been fed ad-libitum silage and approximately 0.25 kg of concentrate daily for 8 weeks. Rectal temperature is 38.5°C (101.3°F). There are no cranial nerve deficits. Mucous membranes are markedly jaundiced (2.22a). Rumen contractions are reduced and the abdomen is shrunken consistent with inappetence of several days.

1 What conditions would you consider?

2 What further tests could be undertaken?

3 What actions/treatments would you recommend?

4 What control measures could be taken?

CASE 2.23 You are presented with a 15-month-old pedigree Suffolk ram that drops its cud along with a large volume of ruminal fluid at the start of rumination (2.23). The farmer describes this as ‘cud spilling' and it has been observed intermittently over the past 3 months. The ram is in much poorer body condition than the other yearlings in the group. The fleece of the ventral neck is stained with regurgitated ruminal contents. The ram has a poor appetite; there is no associated bloat and auscultation of the left flank reveals normal ruminal motility.

1 What is the cause of this problem (most likely first)

2 What action would you take?

3 How could you confirm the cause?

4 Is this condition heritable?

CASE 2.24 During early winter a farmer complains that some yearling sheep purchased 7 weeks ago are in very poor body condition with poor fleece quality despite abundant grazing. On arrival on the farm, the sheep received sequential full-dose treatments with 4-AD monepantel and 3-ML moxidectin. Inspection of other sheep in the group reveals lethargy and reduced grazing activity. Gathering the sheep proved difficult because they were reluctant to run. On clinical examination affected sheep show marked anaemia. One sheep has died this morning and is available for postmortem examination (2.24).

1 Describe the important postmortem features.

2 What is the most likely cause?

3 How could this problem be confirmed in other sheep in the group

4 What action would you take?

CASE 2.25 During summer you are presented with a 4-year-old ewe in very poor body condition (BCS 1.5/5). There are multiple well-circumscribed 5 mm diameter scabs (bottle-brush lesions) around the muzzle, bridge of the nose and on the margins of the ears (2.25), which lift off exposing ulcerated skin that bleeds readily.

1 What conditions would you consider (most likely first)?

2 What further tests could be undertaken?

3 What actions/treatments would you recommend?

4 What control measures could be taken?

CASE 2.26 A 4-year-old ewe presents in much poorer body condition (BSC 1.5/5) compared with others in the flock (BCS 3/5). The sheep has a very drawn-in abdomen and appears ‘wasp-waisted' (2.26a). The ewe is otherwise bright and alert and has a normal appetite. The ewe is afebrile (39.6°C [103.3°F]) but tachypnoeic (48 breaths per minute), with an obvious abdominal component to her breathing. Auscultation of the chest reveals no heart or lung sounds on the right-hand side of the chest but increased heart and normal breath sounds on the left side of the chest. The heart rate, audible on the left side only, is 88 beats per minute.

1 What conditions would you consider

(most likely first)?

2 How would you investigate this problem further?

3 What treatment would you administer?

4 What is the likely cause?

CASE 2.27 You are presented with a yearling Cheviot ram with mild (3/10) lameness of the right fore leg (2.27a). There is considerable muscle atrophy over the scapula of the affected leg but no enlargement of the prescapular lymph node. There are no joint effusions. There is a prominent ridge of bone on the distal humerus and proximal radius of the right elbow, which is not present on the left elbow. Examination of the foot reveals no abnormality.

1 What conditions would you consider (most likely first)?

2 What further tests could be undertaken?

3 What actions/treatments would you recommend?

4 What control measures could be taken?

CASE 2.28 A 2-year-old ram presents off colour and inappetent for the past 2 days. The ram is noted lying around more than the other rams in the group, with occasional

‘dog sitting', and shows occasional abdominal straining, but only a few drops of blood-stained urine are voided rather than a continuous flow. Rectal temperature is normal. Heart rate is increased to 100 beats per minute. Mucous membranes are normal. Auscultation of the chest fails to reveal any abnormalities. Rumen fill and motility are reduced. Ultrasonography reveals the bladder to be 16 cm in diameter (2.28a).

1 What conditions would you consider (most likely first)?

2 What further investigations could be undertaken?

3 What action would you take?

4 What sequelae could result in neglected cases?

5 What control measures would you recommend?

CASE 2.29 You are presented with a Suffolk ram with a history of moderate shifting leg lameness with effusion of the fetlock joints (2.29a). The ram spends a lot of time in lateral recumbency. There are no obvious foot lesions. The ram has lost considerable body condition over the past 2 months. Rectal temperature is elevated (40.2°C [104.4°F]). Heart rate is elevated at 112 beats per minute and the respiratory rate is 45 breaths per minute. No abnormal sounds are heard on auscultation of the lungs and heart.

1 What conditions would you consider (most likely first)?

2 How could you confirm your diagnosis?

3 What treatment would you

administer?

4 What action would you recommend?

5 What control measures would you recommend?

CASE 2.30 During lambing time a sheep farmer complains that a large number of young lambs have tear staining of the face, leading to blindness in some cases. Closer examination reveals conjunctivitis, episceral injection and corneal oedema in some lambs (2.30a).

1 What conditions would you consider (most likely first)?

2 What treatments would you administer?

3 What are the consequences of no action/treatment?

4 What preventive measures could be adopted?

CASE 2.31 Four of 200 6-month- old lambs experience difficulty in raising themselves to their feet and have a stilted gait with low head carriage (2.31a). Lameness was first noted at 3 months old. All of the lambs have one or both stifle joints affected. Two lambs have bilateral carpal swellings with associated enlargement of the prescapular lymph nodes. There is little joint effusion but marked thickening of the joint capsule (2-3 mm), which physically restricts joint excursion.

1 What conditions would you consider?

2 What is the likely cause?

3 How would you confirm the cause?

4 What treatment would you administer?

5 What control measure(s) would you recommend?

CASE 2.32 A 7-month-old Suffolk-cross lamb presents with severe lameness (10/10) of the left hindleg and marked muscle atrophy over the hip region. There are no joint swellings from the stifle joint distally to the foot. A ventrodorsal view of the pelvis is shown (2.32a).

1 Describe the major radiographic changes.

2 What is the likely cause?

3 What treatment would you recommend?

CASE 2.33 A ram presents with a history of chronic weight loss (BCS 2.5/5) when the remainder of the group is within a range of from 3.5/5 to 4/5. The ram has a poor appetite and the rectal temperature is 40.0°C (104°F). At rest the ram is tachypnoeic (40 breaths per minute). Auscultation of the chest reveals no audible lung sounds on the left-hand side of the chest and much reduced heart sounds. Increased audibility of normal heart and lung sounds can be auscultated on the right-hand side of the chest.

This sonogram (2.33a) was obtained from the 6th intercostal space, 5 cm dorsal to the point of the left elbow, using a 5.0 MHz sector transducer (longitudinal plane, dorsal to the left).

1 Describe the sonogram.

2 What is your diagnosis?

3 What treatment(s) would you administer?

4 What is the origin of this pleurisy?

CASE 2.34 This sonogram (2.34a) was obtained using a 5 MHz sector scanner placed on the ventral midline immediately caudal to the xiphisternum. The ewe was presented in early winter in very poor condition, inappetent but with abdominal distension. Other recently purchased sheep in the flock were in poor body condition despite free access to good quality grass silage.

1 Describe the important sonographic findings.

2 What tests would you undertake?

3 What causes would you consider?

4 How would you confirm your diagnosis?

5 What treatment(s) would you administer?

6 Are there any control measures to recommend?

CASE 2.35 In the UK, and many other sheep-producing countries, farmers provide sheep with improved nutrition by means of access to a good grass sward for up to 6 weeks before mating (2.35a) and during the early breeding season (‘flushing’).

1 Briefly list the advantages and disadvantages of flushing.

2 List the alternatives that can achieve appropriate body condition scores at mating, and more lambs.

CASE 2.36 You are presented with a 3-month-old pedigree Suffolk ram lamb that has been dull and inappetent for the past 12 hours. The previous day the lamb was observed to frequently kick at its abdomen, lie down then rise again almost immediately. There was frequent bruxism and vocalisation. On clinical examination, the ram has a distended abdomen with a fluid thrill. Rectal temperature is normal. Heart rate is increased at 120 beats per minute. The lamb shows abdominal straining but only a few drops of urine rather than a continuous flow are voided when it urinates. The penis cannot be extruded in such young lambs. A sonogram of the ventral abdomen was obtained (2.36a).

1 Interpret the sonogram.

2 What is your diagnosis?

3 What other structure(s) should be checked sonographically?

4 What further tests could be undertaken?

5 What action would you recommend?

CASE 2.37 You have been asked to blood sample a group of rams for an annual visna-maedi screen. You are presented with the ram shown (2.37a).

1 What concerns you about the ram?

2 What action would you take?

3 What advice would you offer the farmer?

CASE 2.38 You arrive on a sheep farm to find the shepherd happily paring all four feet of all the rams in the flock (2.38a). He reports that foot paring is routinely undertaken every 6 months to prevent footrot.

1 Does routine foot paring reduce lameness, especially footrot?

2 Are there any potential disadvantages of routine foot paring?

3 What control strategies could be suggested for footrot in this flock?

CASE 2.39 Necropsy of a 2-month-old lamb reveals lesions of the chest wall (2.39a). A radiograph was obtained at necropsy to show the extent and location of the bony lesions (2.39b).

1 What are these lesions?

2 Comment on the welfare of this lamb with respect to these lesions.

3 What is the most likely cause?

4 Apart from difficulty with breathing, what other clinical signs may have been present?

5 How could this problem have been avoided?

CASE 2.40 A 4-month- old twin pedigree ewe lamb presents with an arched back, distended abdomen and abdominal pain. The lamb is at pasture with its co-twin and dam with ad-libitum access to a creep area containing 16% crude protein concentrate. The lamb is dull and is easily caught in the field. On clinical examination, there is marked dehydration (estimated to be >7%) despite a distended abdomen. There is no evidence of diarrhoea. Gentle palpation of the distended abdomen causes pain. Rectal temperature is 39°C (102.2°F). Transabdominal ultrasound examination immediately caudal to the xiphisternum yields the sonogram shown (2.40a).

1 Describe the important sonographic findings.

2 What conditions would you consider (most likely first)

3 What treatment would you administer?

4 How can this problem be avoided?

CASE 2.41 Arriving on a sheep and beef farm at lambing time you observe several dead lambs in the lambing shed.

1 What has happened in 2.41a?

2 Is this practice common?

3 What advice must be given to farm staff?

4 Are there any alternatives to this practice?

CASE 2.42 A Texel yearling ram presents in severe respiratory distress with its head lowered and the neck extended (2.42a). The condition was first noted 2 days ago but has deteriorated rapidly. The ram’s respiratory rate is increased to 90 breaths per minute with a loud inspiratory noise (honking sound) audible 25 yards away from the animal. The ram’s nostrils are flared and the mouth is held open with the tongue partially protruded and frothy saliva around the mouth and lower jaw. Rectal temperature is 40.2°C (104.4°F).

Auscultation over the larynx reveals very loud crackles transferred to the whole lung field. Heart rate is increased to 120 beats per minute.

1 What conditions would you consider (most likely first)

2 How could you confirm your diagnosis?

3 What actions/treatments would you recommend?

4 What controls measures would you recommend?

CASE 2.43 A 3-day-old 7 kg (15.4 lb) pedigree ram lamb presents with a displaced fracture of the left third metatarsal bone (2.43a).

1 How would you achieve effective analgesia for fracture realignment and repair?

2 How would you repair the fracture?

3 What other treatments would you recommend?

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CASE 2.44 During wet and warm summer weather a sheep farmer complains of severe lameness spreading rapidly through his ewes at pasture. Examination of several sheep reveals marked hyperaemia of interdigital skin with superficial accumulations of moist, whitish, necrotic material. There is also separation of the axial hoof horn of the sole from the corium, which is swollen, hyperaemic and covered with a thick white exudate (2.44a). There is a characteristic smell of necrotic horn/exudate.

1 What is the likely cause (most likely first)?

2 How is the diagnosis confirmed?

3 What treatment would you administer?

4 What control measures would you include in the flock health plan?

CASE 2.45 During autumn you are asked to examine a two-crop ewe with a large fibrous mass arising from the udder, which bleeds readily as evidenced by blood on the medial aspect of the hindlegs (2.45a). The ewe is otherwise well and in excellent body condition.

1 What is the likely cause?

2 What action would you take?

3 What control measures could be adopted?

CASE 2.46 A ewe presents with a history of chronic weight loss (BCS 1.5/5) when the remainder of the group is within a range of from 3.5/5 to 4/5. The ewe has a good appetite and a normal rectal temperature. Auscultation of the chest reveals no abnormality. Mucous membranes appear normal. During the clinical examination, the ewe urinates onto the concrete floor of the pen; the urine is blood-tinged. Urine analysis

reveals protein +++ and blood +++

(scale 1-4). There are no flecks of blood or pus on the ewe’s tail or hind quarters.

A provisional diagnosis of renal neoplasia is reached during ultrasound examination of the caudal abdomen, but a separate structure (2.46a) was also obtained from the right inguinal region (5.0 MHz sector transducer).

1 Describe the sonogram.

2 What is this structure (most likely first)

3 What action would you take?

CASE 2.47 A 4-year-old ewe presents in much poorer body condition (BSC 1.5/5) compared with others in the flock (BCS 3/5). The ewe is bright and alert and has a normal appetite (2.47a). The ewe is afebrile (39.6°C [103.3°F]) but tachypnoeic (47 breaths per minute) with an obvious abdominal component to her breathing. Auscultation of the chest reveals widespread wheezes and crackles, especially distributed anteroventrally on both sides of the chest. Heart rate is 88 beats per minute.

1 What conditions would you consider (most likely first)?

2 How would you confirm the diagnosis?

3 What treatment would you administer?

4 What control measures could be attempted in this flock?

CASE 2.48 You are presented with a valuable pedigree 4-day-old lamb with sudden-onset moderate lameness of the right fore leg. There are no palpable joint swellings and the right prescapular lymph node is normal size. Pain is localised to the metacarpal region. Radiography yields the image shown (2.48).

1 What is the cause of the lameness?

2 What other conditions would you consider?

3 How would you correct this problem?

CASE 2.49 Driving to a farm to attend to a lame bull you observe a 4-month-old lamb abruptly stop grazing and turn its head and attempt to nibble at its tail head (2.49a). The lamb then suddenly trots away with frequent tail swishing before recommencing grazing. This cycle of abnormal behaviour is repeated several times. The fleece surrounding the lesion appears wet and discoloured.

1 What is the cause (most likely first)?

2 What treatment options would you consider?

3 What control measures would you recommend to the farmer?

2.50a

CASE 2.50 You are presented with a pedigree ram that has been dull and inappetent for the past 3 days. The ram adopts a wide stance with the hindlegs placed further back than normal and the head held lowered. There is frequent bruxism. Only a few drops of blood-tinged urine are voided when the ram urinates, rather than a 15-20 second continuous flow. Rectal temperature is normal (39.5°C [103.1°F]). The ram has a poor appetite. Heart rate is I increased at 96 beats per minute.

You suspect partial obstructive urolithiasis and scan the right sublumbar fossa with a 5.0 MHz sector transducer connected to a real-time, B-mode ultrasound machine (2.50a).

1 Describe the sonogram.

2 What has caused this problem?

3 What action would you take?

4 How could this problem have been prevented?

CASE 2.51 You are presented with an aged Texel ram with a ‘horny’ growth in the centre of the poll (2.51).

1 What is the lesion?

2 What is the likely cause?

3 What action would you take?

CASE 2.52 In summer a farmer complains that some ewes have lost considerable condition as a consequence of not grazing and lying around with their heads on the ground. The ewes appear distressed and frequently kick at their head with their hindfeet, causing superficial damage to the skin of the poll and ears (2.52).

1 What is the cause of this problem (most likely cause first)?

2 How can this problem be controlled?

CASE 2.53 You arrive at a mixed beef and sheep farm during late winter, 2 months before lambing time, to examine a lame bull. The flock has just been housed and are bedded on straw (2.53a) and fed big bale silage (2.53b).

1 Comment on the quality of the straw and any associated disease risks to pregnant ewes.

2 Comment on the silage feeding and any associated disease risks.

3 How can these disease risks be reduced?

CASE 2.54 Having read an article in a magazine for farmers on the value of necropsy examinations in modern sheep farming, a client asks you to necropsy an ewe that died overnight following body condition loss over several months. There is no evidence of diarrhoea on the fleece. The carcass is emaciated and there is a small excess of transudate in the abdominal cavity. There is serous atrophy of fat, most noticeable in the mesentery and epicardial groove. A section of ileum is shown on the left-hand side compared with jejunum on the right side (2.54a).

1 What is the most likely cause of this pathology?

2 What has this single necropsy revealed?

3 What advice would you offer?

CASE 2.55 A 4-year-old ewe presents with sudden severe illness (2.55a) 2 weeks after housing in late winter and 6 weeks before lambing commences. The ewe is very dull and reluctant to move. Rectal temperature is 41.1°C (106°F). Mucous membranes are markedly congested. The ewe is tachypnoeic (50 breaths per minute) with an obvious

abdominal component. Auscultation of the chest reveals widespread wheezes on both sides of the chest. Heart rate is 124 beats per minute. There are no ruminal

contractions.

1 What conditions would you consider?

2 What action would you take?

3 What treatment would you administer?

CASE 2.56 You are asked to euthanase, then necropsy, a 3-week-old lamb first noted 5-7 days ago to be dull and in much poorer condition than its co-twin. The lamb had an empty, gaunt appearance and was too easily caught in the field. Treatment with long-acting oxytetracycline has effected no improvement. The significant findings are shown (2.56).

1 What is the cause of this problem?

2 Could this problem have been diagnosed?

3 What treatment should have been given?

4 Could this problem have been prevented?

CASE 2.57 You arrive on a sheep farm in the UK in late spring and the farmer is castrating male hill lambs with rubber elastrator rings (2.57).

Lambing ended 3 weeks ago.

1 What are you thoughts on this subject?

2.58a

CASE 2.58 A 6-year-old ewe presents in poor body condition with a history of blindness of several weeks’ duration, which was unresponsive to vitamin B₁ administered by the farmer. The ewe is dull and depressed and wanders aimlessly into the pen wall and stands there. Clinical examination reveals bilateral lack of menace response and absence of pupillary light reflexes in both eyes (2.58a). There are no abnormalities on ophthalmoscopic examination. No other cranial deficits are noted. The ewe is in very poor condition and the sublumbar fossae are very shrunken, consistent with inappetence of several days’ duration.

1 What conditions would you consider?

2 What treatment would you administer?

3 What action would you take?

CASE 2.59 After severe winter weather conditions of high winds and driving snow a shepherd complains that a large number of heavily pregnant ewes on hill pastures have poor vision and some appear blind. The ewes are markedly photophobic with blepharospasm and epiphora and tear staining of the cheeks. A less severely affected sheep is shown (2.59). Clinical examination reveals injected scleral vessels, conjunctivitis and keratitis.

In some eyes there is also corneal ulceration, more clearly observed after fluorescein dye strips have been placed in contact with the eye.

1 What conditions would you consider?

2 What treatments would you recommend?

3 What action would you recommend?

CASE 2.60 A 4-day-old twin lamb presents with an arched back and apparent abdominal pain. The lamb was turned out to pasture with its co-twin and dam at 24 hours old. It was found this morning by the shepherd sheltering behind a hedge. The lamb was dull and easily caught. On clinical examination, there is marked dehydration (estimated to be >7%) despite a distended abdomen (2.60a). There is no evidence of diarrhoea. Gentle palpation of the distended abdomen causes pain. Rectal temperature is 37°C (98.6°F).

1 What conditions would you consider (most likely first)?

2 What treatment would you administer?

3 What action should be taken?

4 How can this problem be avoided?

CASE 2.61 You are presented with a ewe in poor body condition (BCS 2/5) that has developed a swollen udder (2.61) since weaning 4 months ago. Rectal temperature is normal (39.6°C [103.3°F]). Pulse is 90 beats per minute and respiratory rate is 25 breaths per minute. There are normal ruminal sounds. Examination of the udder reveals marked swelling and hardness of the left gland. There is evidence of wool-slip.

1 What is the likely diagnosis?

2 Are there any consequences of such conditions?

3 What pathogens could be involved?

4 What is the prognosis?

5 What control measures could have been adopted?

CASE 2.62 A 5-crop ewe, scanned for twins and due to lamb in 3 weeks, is found in the corner of the shed unable to raise itself. This group of ewes was housed 3 weeks ago and fed 300 g of concentrates plus ad-libitum hay. The ewes were vaccinated against the clostridial diseases 2 days ago. The ewe is dull and unable to rise as you approach (2.62a).

Rectal temperature is normal but the rectum is flaccid and contains a ball of firm faeces. Heart rate is 80 beats per minute. Respiratory rate is 40 breaths per minute. There are no cranial nerve deficits. There is ruminal stasis and slight bloat. The udder is well developed, there is no mastitis and there is no vulval discharge.

1 What conditions would you consider (most likely first)?

2 How could you confirm your diagnosis?

3 What treatment(s) would you administer?

4 What control measures would you recommend?

CASE 2.63 You are presented with an adult sheep that is continually rubbing against pen divisions and nibbling at her fleece overlying the dorsal midline, causing fleece damage/loss (2.63). The ewe is in much poorer condition than all the other sheep in the group, which do not show any signs of skin disease. The sheep is bright and alert with a normal appetite.

1 What conditions would you consider?

2 How would you establish a specific diagnosis?

3 What treatment would you recommend?

4 What control measures would you recommend?

CASE 2.64 Comment on this image (2.64).

CASE 2.65 A 4-year-old ewe presents in poor body condition (BCS 1.5/5; remainder of the flock are 3.0-3.5/5; normal range 1-5/5). The ewe is bright and alert with a normal appetite. Rectal temperature is 39.6°C (103.3°F). Mucous membranes appear normal. At rest the ewe is tachypnoeic (50 breaths per minute) with an obvious abdominal component. Auscultation of the chest reveals wheezes anteroventrally on both sides of the chest. Heart rate is 96 beats per minute. No other abnormalities are detected on clinical examination. This sonogram (2.65a) was obtained at the sixth intercostal space, just above the point of the left elbow, using a 5 MHz linear scanner (dorsal to the left).

1 Describe the important ultrasound findings.

2 How could you confirm the provisional diagnosis?

CASE 2.66 You arrive on a sheep farm during lambing time and the shepherd is assisting delivery of a lamb from an ewe experiencing difficulties (2.66a).

1 Comment on the hygiene approach to this common scenario.

CASE 2.67 A 3-week-old lamb shows seizure activity. The farmer reports that the lamb was observed in the field walking backwards. Rectal temperature is 40.0°C (104.0°F). The lamb now presents in lateral recumbency with the fore legs held in rigid extension, flexion of the hindlegs and dorsiflexion of the neck (2.67). The lamb is hyperaesthetic

to tactile and auditory stimuli. Gentle forced movement of the neck is resisted. There is episcleral congestion and dorsomedial strabismus. The menace response is absent. There is no umbilical swelling and no joint swellings.

1 What conditions would you consider (most likely first)

2 How could you confirm your diagnosis?

3 What treatment(s) would you administer?

4 What is the prognosis for this lamb?

CASE 2.68 During late winter you are presented with an obtunded 2-year- old ram (2.68a). The sheep shows drooping of the right ear, deviated muzzle towards the left side, a flaccid right lip and a lowered right upper eyelid (ptosis). There is lack of menace response in the right eye and profuse salivation with a flaccid right cheek with impacted food material.

1 What conditions would you consider (most likely first)?

2 What laboratory tests could be undertaken to confirm your provisional diagnosis?

3 What treatments would you administer?

4 What control measures would you recommend?

2.69a

I CASE 2.69 A ewe in late pregnancy is reported to be dull and not eating (2.69a). There is no menace response but pupillary light reflexes are normal. The ewe is hyperaesthetic to tactile and auditory stimuli. Rectal temperature is normal. The ewes are being fed ad-libitum average quality big bale silage plus 200 g/head/day of a 16% crude protein concentrate. The flock is due to start lambing in approximately _ —1 2 weeks. The ewe is in poorer body condition (BCS 1.5/5) compared with other sheep in the group at a similar stage of pregnancy (BCS 2.5-3.0/5).

1 What conditions would you consider (most likely first)?

2 How could you confirm your diagnosis?

3 What treatment(s) would you give?

4 What control measures could be adopted?

CASE 2.70 A ram presents with a history of chronic weight loss (BCS 2/5) when the remainder of the group is within a range of from 3.5/5 to 4/5. The ram is at the back of the group when gathered from the field. He appears to have a normal appetite and rectal temperature is 39.8°C (103.6°F). At rest, the ram is tachypnoeic (40 breaths per minute). Auscultation of the chest reveals no adventitious sounds. The heart sounds are reduced on the left hand side of the chest. There are no other significant clinical findings. This sonogram (2.70a) was obtained from the sixth intercostal space, at the point of the left elbow, using a 5.0 MHz sector transducer (longitudinal plane, dorsal to the left). Similar but smaller lesions were identified in both lungs.

1 Describe the sonogram.

2 What is your diagnosis?

3 What treatment(s) would you administer?

4 What other imaging modality could have been used?

CASE 2.71 A 6-year-old ewe presents in very poor body condition (BCS 1.5/5) while the other sheep in the group have BSCs of 3/5 to 4/5. The ewe has a gaunt appearance and a poor fleece (2.71a). Rectal temperature is 39.4°C (102.9°F). Poorly masticated food is often dropped from the mouth (^ςquidding^,). Closer examination reveals a lot of roughage impacted in the cheeks.

1 What conditions would you consider (most likely first)?

2 How would you investigate this problem?

3 What actions/treatments would you recommend?

CASE 2.72 A farmer reports diarrhoea and rapid weight loss over the past 2-3 days in a large percentage of 8-week-old lambs grazing permanent pasture (2.72a).

1 What common conditions would you consider (most likely first)?

2 What tests could be undertaken to support your provisional diagnosis?

3 What control measures would you recommend?

CASE 2.73 A farmer complains of skin lesions on the muzzle and lips of approximately 25% of 120 6-month-old lambs 10-14 days after movement onto pastures containing large numbers of thistles (this field is a site of special scientific interest). The skin is oedematous with excoriation of lesions where they contact the ground during grazing (2.73).

1 What conditions would you consider (most likely first)?

2 What treatment would you administer?

3 What samples would you collect to confirm your diagnosis?

4 What preventive measures could be considered for next year?

CASE 2.74 A farmer complains that 10 of 30 pedigree Texel lambs have abnormal eyes (2.74) and are blind. All affected lambs are thought to be the progeny of a pedigree ram used for the first time in the flock.

1 What is the likely cause (most likely first)?

2 What action would you take?

3 What advice would you offer?

CASE 2.75 A 10-week-old lamb presents in very poor body condition with a poor fleece (2.75a). The lamb is depressed, dehydrated and frequently stands over the water trough. Rectal temperature is normal. Its co-twin, and other lambs in the group, appear healthy and are growing well.

1 What conditions would you consider?

2 How would you confirm your diagnosis?

3 What is the prognosis for this lamb?

4 What control measures would you recommend?

CASE 2.76 A 4-week-old lamb is found dead without premonitory signs. The lamb is in excellent body condition. The significant necropsy findings are restricted to the chest (2.76a, b).

1 Describe the important necropsy findings shown.

2 What is the most likely cause?

3 How could you confirm your suspicion?

4 What control measures could be adopted?

CASE 2.77 During lambing time you are presented with a 12-day-old lamb with non­weight-bearing lameness of the left fore leg of 5 days’ duration (2.77a). This lamb, and four similarly affected lambs, have been treated with oxytetracycline by the farmer without improvement in the past week. The lamb’s rectal temperature is normal. There are joint swellings of the left elbow and right carpus, with swollen prescapular lymph nodes. The umbilical stump is dry and brittle.

1 What is your diagnosis (most likely first)?

2 How would you confirm your diagnosis?

3 What treatments would you administer?

4 What preventive measures could be adopted?

CASE 2.78 You are presented with a collapsed ewe with a vaginal prolapse 3 weeks prior to lambing (2.78a).

1 How will you deal with this case?

2 What is the future management of this sheep?

CASE 2.79 You are presented with a recumbent yearling sheep at pasture (2.79a). The previous day the farmer noted that the sheep was blind and wandered aimlessly and appeared to be ‘star-gazing’. On veterinary examination, the sheep is hyperaesthetic to auditory and tactile stimuli, which precipitate seizure activity. Dorsomedial strabismus and spontaneous horizontal nystagmus are present. There is no menace response in either eye. No other abnormalities are detected on clinical examination.

1 What conditions would you consider?

2 What treatment would you administer?

3 What is the prognosis for this case?

4 How can the diagnosis be confirmed?

5 What control measures would you recommend?

CASE 2.80 During early summer a pedigree 4-year-old ewe nursing 2-month-old twin lambs presents with an arched back and a markedly distended abdomen (2.80a). The ewe has been moved to lush pasture 2 days ago and is also fed 1 kg of a 16% crude protein concentrate once daily. The ewe is dull and easily restrained. On clinical examination there is marked dehydration (estimated to be >7%) with toxic mucous membranes. There is no evidence of diarrhoea. Heart rate is 124 beats per minute and the respiratory rate is shallow at a rate of 46 breaths per minute. Gentle palpation of the distended abdomen causes pain. Rectal temperature is 39.5°C (103.1°F).

1 What conditions would you consider (most likely first)?

2 What further investigations would you undertake?

3 What treatment would you administer?

4 How can this problem be avoided?

CASE 2.81 During the breeding season you are presented with a ram with paraphimosis (2.81) with oedematous folds on the surface of the penis and secondary bacterial infection.

1 What is the cause of this problem?

2 What action would you take?

3 What treatment would you administer?

4 What is the prognosis?

CASE 2.82 After weaning, ewes rearing lambs for meat are often turned out onto poor quality grazing (2.82a) or grazed at very high stocking densities.

1 What is the reasoning behind this management decision?

2 What are the alternative management strategies?

CASE 2.83 During late summer a client asks for advice regarding internal parasite control for 400 purchased store lambs that will graze silage aftermath for approximately 3 months (2.83). Any lambs not reaching market weights will then be housed and fattened intensively on cereals; margins are tight.

1 What advice would you give?

CASE 2.84 You are asked to undertake a postmortem examination on a 4-year-old ewe in poor body condition. Examination of the rumen wall identifies the structures shown (2.84).

1 What are these lesions?

2 Are these lesions important?

3 What action would you recommend?

CASE 2.85 A 4-month-old ewe lamb is found dead without premonitory signs; the ewes and lambs had been checked the previous morning and no sick sheep were observed. The lamb is in excellent body condition. The only finding is the presence of frothy saliva at the mouth (2.85a).

1 What conditions can cause sudden death in growing lambs (most likely first)?

2 How could you confirm your suspicion?

3 What control measures could be adopted?

CASE 2.86 A sheep farmer comments that he has seen ribbon-like segments in the faeces of many of his 3-month-old lambs (2.86).

1 What are these ribbon-like segments?

2 What action is necessary?

3 What control measures would you recommend?

CASE 2.87 During early autumn, 1 month ahead of the breeding season, a sheep farmer asks about anthelmintic treatment of his ewes pre-tupping (2.87a).

1 What advice would you give?

CASE 2.88 A ewe presents with a history of chronic weight loss (BCS 1.5/5) when the remainder of the group is within a range of from 3.5/5 to 4/5. The ewe has a good appetite and a normal rectal temperature. Auscultation of the chest reveals no abnormality. During the examination, the ewe urinates onto the concrete floor of the pen; the urine is blood-tinged. Urinalysis reveals protein +++ and blood +++ (scale + to ++++). There are no flecks of blood or pus on the ewe’s tail or hindquarters. This sonogram (2.88a) was obtained from the right inguinal region with the 5.0 MHz sector transducer pointed vertically towards the tailhead of the ewe.

1 Describe the sonogram.

2 What is this structure (most likely first)

3 What action would you take?

CASE 2.89 During mid-summer you are driving to a sheep and beef farm and notice that the rams are all scouring and appear to be in poor condition (2.89). The 20 rams graze the same 4-hectare field every year.

1 What common conditions would you consider (most likely first)?

2 What tests could be undertaken to support your provisional diagnosis?

3 What control measures would you recommend?

CASE 2.90 A sheep farmer houses his sheepdogs in the same building used for rearing orphan lambs. The dogs, including a litter of young puppies, frequently defecate in the hay offered to these lambs (2.90a, arrow).

1 Are there any risks to these young lambs?

2 What clinical signs would be expected?

3 What signs may be noted in these lambs at slaughter?

4 What simple hygiene measures would you recommend?

CASE 2.91 During clinical examination of an aged ewe in poor body condition two small masses can be palpated in the ventral abdomen. Ultrasound examination reveals four 3-4 cm diameter lesions (2.91a).

1 What is the lesion shown in the sonogram (most likely first)?

2 What is the significance of these lesions?

3 What action would you recommend?

CASE 2.92 Two weeks after weaning and turnout onto lush grazing, a 5-month- old hill lamb is found isolated from the group and appears very dull and is easily

caught. The lamb is in good condition. There is frothy saliva at the mouth (2.92a) and the mucous membranes are congested. Rectal temperature is 40.8°C (105.4°F). Auscultation of the chest fails to reveal any adventitious sounds, although the respiratory rate is increased to 40 breaths per minute. There is evidence of recent diarrhoea, although the lambs were treated with a Group 4 anthelmintic (monepantel) when

turned onto this safe grazing.

1 What conditions would you consider (most likely first)

2 What treatment would you administer?

3 What control measures could be adopted?

CASE 2.93 You are asked to necropsy a week-old twin lamb that was found dead in the field this morning. There is no milk in the abomasum and the lack of carcass fat is consistent with death from starvation/mismothering/ exposure. The other important findings are shown (2.93a).

1 What is the cause of this problem?

2 Where would you extend your necropsy examination?

3 Could this problem have been prevented?

CASE 2.94 Towards the end of the breeding season a pedigree ram presents suddenly lame on the left fore leg, with weight taken on the dorsal surface of the hoof (2.94). The ram is at pasture with 120 ewes and two other rams. The farmer thinks that the rams have simply been fighting and elects to do nothing. One week later the ram is still unable to fully extend the left fore leg and bear weight. The ram was fitted with a keel harness, which may have been too tight, as there are pressure sores. The ram is eating normally, although it has lost considerable body condition. There is obvious loss of muscle over the scapula, with a more prominent spine than on the right side. There is a dropped elbow, flexion of the distal limb joints and scuffing of the hooves as the left leg is moved forward. The foot remains knuckled over at rest. The left prescapular lymph node is not swollen. There is no pain on careful manipulation of the leg.

1 What conditions would you consider (most likely first)?

2 What treatment(s) would you administer?

3 What is the prognosis for this ram?

CASE 2.95 While on a sheep farm in winter you are presented with a yearling sheep with no ears (2.95a). The sheep is in excellent condition.

1 What has happened to this sheep?

2 Could anything have been done to prevent this situation?

3 Should this sheep be kept for future breeding?

CASE 2.96 You are presented with an aged ewe with severe (10/10) lameness of the right hindleg and extensive muscle atrophy over the hip region. There is marked thickening of the joint capsule but no palpable effusion of the stifle joint; no other joint feels abnormal. Based on these clinical findings the ewe is euthanased for welfare reasons and lateral and dorsoplantar radiographs obtained of the right stifle region (2.96a, b).

1 Comment on the radiographs.

2 Comment on the animal welfare implications of these findings.

3 What are the expected necropsy findings?

4 What advice should be given to the farmer?

CASE 2.97 A sheep client is keen to show off his recent purchase of eight rams from prominent breeders (2.97).

1 What advice would you offer regarding flock biosecurity?

CASE 2.98 During wet warm summer weather a sheep farmer complains that many of his lambs have gone suddenly lame and are grazing on their knees. Examination of several lambs reveals superficial accumulations of moist, whitish, necrotic material on the hyperaemic interdigital skin (2.98a). There is no separation of the axial hoof horn of the sole from the corium. There are no palpable joint swellings.

1 What is the likely cause (most likely first)?

2 What treatment would you administer?

3 What control measures would you include in the flock health plan?

CASE 2.99 You are presented with a ewe with a Cervicovaginal prolapse and fetal membranes protruding through the cervix, indicating impending abortion/ parturition (2.99a). There is no foetid vaginal discharge. The ewe is shown in right lateral recumbency and preparations are underway for surgery.

1 Do you agree with the

decision to undertake a caesarean operation?

2 What anaesthetic protocol would you adopt?

CASE 2.100 A Suffolk ram presents with severe lameness (10/10) of the left hindleg and marked muscle atrophy over the hip region. The left hindfoot is swollen with marked widening of the interdigital space. There is loss of hair and thinning of the skin all around the coronary band of the medial claw, extending proximally for 1.5 cm (2.100a).

1 What conditions would you consider?

2 How would you confirm your diagnosis?

3 How long has this ram been lame?

4 What treatment would you recommend?

CASE 2.101 You are presented with a valuable 1-month-old ram lamb with severe (9/10) lameness of the right fore leg and extensive muscle atrophy over the scapula. There is thickening of the joint capsule of the shoulder and elbow joints but no obvious effusion. The right prescapular lymph node is markedly enlarged. All other joints feel normal. The lamb has been treated for the past 5 consecutive days with penicillin injected IM. A lateral radiograph of the right fore leg is obtained (2.101a).

1 Comment on the radiograph.

2 What action would you take?

CASE 2.102 During winter you are presented with a group of 120 yearling sheep, many of which are very uncomfortable and nibble at their flanks and rub themselves against the pen divisions. Some ewes appear in considerable distress and kick at themselves with their hindfeet, causing fleece loss over the shoulder region (2.102a). The fleece is wet, sticky and yellow with serum exudation.

1 What conditions would you consider?

2 How would you confirm the diagnosis?

3 What treatment would you administer?

4 What control measures could be adopted?

CASE 2.103 During lambing time a farmer with a prolific sheep flock complains that approximately 10-15% of twin lambs are much smaller than their co-twins (2.103) despite adequate energy feeding during late gestation. The ewes appear to be in adequate body condition (BCS 2.5/5).

1 What are the possible causes of this problem?

2 What action can be taken?

CASE 2.104 Before the start of the breeding season you are asked to check the breeding soundness of 22 rams on a sheep farm. The rams are in excellent body condition and there is no lameness in the group. Palpating the scrotum of an aged ram reveals a bilobed structure in each side of the scrotum, with each lobe measuring approximately 5 cm in diameter. These bilobed structures are firmly adherent to vaginal tunics lining the scrotum; the skin of the scrotum is thickened and slightly oedematous. A sonogram was obtained of the distal mass of these bilobed structures (2.104a; proximal to the left).

1 Describe the important features in the sonogram.

2 What conditions would you consider (most likely first)?

3 What action would you take?

CASE 2.105 You are asked to necropsy several neonatal lambs by a sheep farmer who is experiencing losses at lambing time. A consistent finding in the necropsies is highlighted (2.105a).

1 What is the significant finding?

2 What other supporting evidence would you check for in the cadaver?

3 What other supporting evidence would you check for on the farm?

CASE 2.106 A farmer complains of a large proliferative skin lesion on one leg only extending proximally from the coronary band (2.106) and causing severe lameness in two of 120 purchased 8-month-old lambs. These lesions were first noted approximately 1 month after movement onto pastures containing large numbers of thistles. Examination of both lambs reveals that the large granulomatous mass extends 4 cm proximally from the coronary band and bleeds profusely when traumatised.

1 What conditions would you consider (most likely first)?

2 What treatments would you administer?

3 What samples would you collect?

4 What preventive measures could be considered for next year

CASE 2.107 You are presented with a twin-bearing ewe with a vaginal prolapse 2 weeks prior to lambing. There is marked oedema of vaginal mucosa and vulva (2.107a).

1 How will you deal with this case?

2 What is the future management of this sheep?

CASE 2.108 During autumn you are asked to investigate several sudden deaths in a flock over the past week. The breeding season started 6 weeks ago. The farmer suspects the losses are caused by ovine pulmonary adenocarcinoma. Unfortunately, no carcasses are available for necropsy, although one ewe is dull and depressed and is presented for examination at the veterinary surgery. Transthoracic ultrasound examination of the lungs using a 5 MHz sector scanner reveals no abnormality, but this sonogram (2.108a) was obtained from the right-hand side of the lower cranial abdomen.

1 Describe the important sonographic findings.

2 What tests would you undertake?

3 What treatment(s) would you administer?

4 What could be a major consequence of this problem?

CASE 2.109 During early summer you are presented with a 2-month-old lamb with tetraparesis of approximately 2-weeks' duration (2.109a). Rectal temperature is normal. There are no joint swellings and no swollen lymph nodes. The reflex arcs are reduced in the hindlegs (2.109b). There is no evidence of cervical pain and no subcutaneous swelling in the neck region.

1 What is your diagnosis (most likely first)?

2 What treatments would you administer?

3 How could you confirm your diagnosis?

4 What preventive measures could be adopted?

CASE 2.110 A pedigree ram presents with severe lameness (10/10) of the left hindleg, with marked muscle atrophy over the hip region. The left hindfoot is swollen, with marked widening of the interdigital space. There is loss of hair and thinning of the skin around the coronary band of the lateral claw, extending proximally for 1.5 cm. A dorsoplantar radiograph is obtained (2.110a).

1 Comment on the major radiographic findings.

2 What condition would you consider?

3 How long has this ram been lame?

4 What treatment would you recommend?

CASE 2.111 A potentially valuable 2-month-old pedigree ram lamb is bright and alert but unable to use its hindlegs and adopts a dog-sitting position (2.111a). The fore leg reflexes are normal, while there are increased reflexes in the hindlegs. The flock is intensively managed and has been housed since before lambing time. The farm dogs are kennelled in the corner of the sheep shed. The lamb has exhibited no abnormalities until noted by the farmer 2 days ago; no other sheep show similar signs. The lamb has been treated with procaine penicillin but without improvement.

1 What conditions would you consider (most likely first)?

2 How would you confirm your diagnosis?

3 What action would you take?

CASE 2.112 You are asked your opinion on the skull of an aged Soay ewe (2.112a, b). There are no dental abnormalities.

1 What are the important features?

2 What clinical signs would this sheep have presented with?

3 What advice would you offer?

CASE 2.113 A ram presents with a 1.5 cm diameter red growth beneath the hoof horn of the toe of the lateral claw of the right fore foot (2.113a). The lesion is non­painful and attached to the corium by a 5 mm stalk.

1 What might this mass be (most likely first)?

2 What factors contribute to this condition?

3 What would you do to correct this problem?

4 What advice would you offer about future control?

CASE 2.114 A ewe is found separated from the remainder of the group of lambing ewes. On clinical examination the ewe is very dull and depressed with an elevated rectal temperature (40.5°C [104.9°F]). Mucous membranes are congested. Heart rate is 130 beats per minute. The abdomen is markedly distended (2.114a). The udder is well developed and there is some accumulated colostrum in the glands. There is no vaginal discharge; digital examination of the posterior reproductive tract is restricted by the normal (undilated) vulva.

1 What is your differential diagnosis?

2 What further tests could be carried out?

3 What treatment/action would you consider?

4 What investigations would you undertake?

CASE 2.115 During early winter a farmer reports that a large percentage of his yearling sheep grazing permanent pasture have diarrhoea with faecal staining of the perineum (2.115). The sheep have lost considerable body condition over the past 4 weeks.

1 What conditions would you consider (most likely first)?

2 How would you investigate this problem?

3 What action would you take?

CASE 2.116 You are presented with a ewe that had an assisted lambing 2 hours ago. Severe tenesmus has caused a uterine prolapse (2.116).

1 How will you deal with this case?

CASE 2.117 A sheep farmer asks you to prepare a vasectomised ram ahead of the breeding season.

1 List the potential advantages of management systems using a vasectomised ram.

2 What analgesia/anaesthesia would you employ?

3 How is the vas deferens identified during surgery?

4 How is successful vasectomy confirmed?

5 What is the minimal interval between vasectomy and introduction of the teaser ram to a group of ewes?

CASE 2.118 A 2-month-old twin lamb is bright and alert but unable to use its hindlegs and adopts a dog-sitting position (2.118a). The lamb has exhibited no abnormalities until noted by the farmer 3 days ago. The lamb has been treated for 3 consecutive days with procaine penicillin but without improvement. Examination of the lamb reveals no ticks.

1 What conditions would you consider (most likely first)

2 What is the origin of this problem?

3 What is the significance of no ticks on the lamb?

4 What treatments would you now administer?

5 How can this condition be prevented?

CASE 2.119 A 3-month-old lamb presents with a head tilt towards the right side and spontaneous horizontal nystagmus, with the fast phase directed towards the left side (2.119). There is no circling behaviour. Ventral strabismus (eye drop) is present on the right side. Damage to the right facial nerve has resulted in drooping of the right upper eyelid and drooping of the right ear.

1 What conditions would you consider (most likely first)?

2 What is the likely cause?

3 What treatment would you administer?

4 What is the prognosis for this case?

CASE 2.120 Halfway through lambing time a sheep client complains of high morbidity and mortality in 24-36-hour-old lambs showing excess salivation with a wet lower jaw, cold mouth and poor suck reflex, and retained meconium (2.120). There is progressive abdominal distension with fluid and gas. Rectal temperature is subnormal. There is dehydration and poor peripheral perfusion, with cold extremities and a rapid weak pulse during the agonal stages.

1 What conditions would you consider?

2 What treatments would you recommend?

3 What control measures would you instigate?

CASE 2.121 Comment on the welfare of this group of fattening lambs at the end of winter (2.121a).

CASE 2.122 During autumn several weaned 6-month-old lambs present in very poor body condition and show depression extending to stupor (2.122) and aimless wandering. Many of the other lambs in the group are lethargic with a poor appetite, have poor wool quality with an open fleece, and are in very poor body condition despite adequate nutrition. Some lambs show epiphora with tear staining of the cheeks.

1 What conditions would you consider (most likely first)?

2 How would you investigate this problem?

3 What treatment will you administer?

4 How would you prevent this problem recurring next year?

CASE 2.123 A sheep farmer complains that several of his ewes are losing their fleece soon after lambing (2.123) and well before normal shearing time in 3 months time. On clinical examination, there is no inflammation of the skin, no serum exudation, no excoriation and no pruritus. No lice are visible and skin scrapings for Psoroptes ovis are negative.

1 What is the cause of this condition?

2 What action would you take?

CASE 2.1

1 What common problems could cause sudden death in these weaned unvaccinated lambs (most likely first)? Include: acidosis; septicaemic pasteurellosis; pulpy kidney, struck; acute fasciolosis/black disease; parasitic gastroenteritis (especially Trichostrongylus vitrinus).

2 How could you confirm your provisional diagnosis? Postmortem examination of two lambs reveals rancid fluid ruminal contents (‘soupy consistency') containing large amounts of barley. The rumen pH value is 5.0 (normal >6.5). The contents of the remainder of the intestines are fluid-filled. There are no significant lung/ liver lesions. No glucosuria (a useful field test for pulpy kidney) is detected. Faecal worm egg counts are 100-150 epg.

3 What treatments would you consider? The relatively low economic value of fattening lambs limits treatment considerations to 3-5 consecutive days of IM penicillin injection and a single IV injection of thiamine or multivitamin preparation. Penicillin would be effective against a bacteraemia arising following rumenitis, while multivitamin preparations are believed to aid liver function. The role of bicarbonate-spiked IV fluids (5-10 mEq/kg bicarbonate in 3 litres saline over 3 hours) in recumbent (acidotic?) sheep is cost-prohibitive in most situations. Alternatively, sodium bicarbonate (10-20 g) and activated charcoal can be given by orogastric tube in 5 litres of water. The lambs must be vaccinated against clostridial disease immediately.

4 What control measures would you recommend? Options that could be considered include adding shredded beet pulp in the ration. The following suggestions are not readily applicable to hopper feeding:

• Reduce the ration to 100 g per day immediately.

• Steadily increase the concentrate feeding by 50 g/week ensuring that all feed is eaten with 10 minutes.

• Provide ration ad libitum once all sheep are consuming approximately 250 g/head/day.

CASE 2.2

1 What conditions would you consider (most likely first)? Include: atresia ani/ coli; watery mouth disease (endotoxaemia); bladder distension after urethral constriction by an elastrator ring placed around the penis proximal to the neck of the scrotum; abomasal bloat or volvulus.

2 What action would you take? Clinical examination reveals that the lamb has no anus. A soft swelling is present under the skin where the anus should be.

Administer a caudal block using 0.3 ml of 2% lidocaine solution at the first intercoccygeal or sacrococcygeal site using a 23 gauge 5/8 inch needle. A stab incision is made over the skin bulge with a 15T surgical blade. Incision of the skin bulge releases a large amount of mucoid material (2.2b). The farmer was advised to gently insert a thermometer into the rectum twice daily for the next 7 days to prevent stricture of the incision site. The lamb was treated with procaine penicillin (15 mg/kg IM q24h for 5 consecutive days). The lamb made an uneventful recovery.

Atresia ani is much more common in lambs than calves, whereas atresia coli is more common in calves, although it is possible that cases of atresia coli in lambs are not recognised/presented to veterinary practitioners.

CASE 2.3

1 What common problems would you consider (most likely first)? Actinobacillosis; caseous lymphadenitis (CLA).

Actinobacillosis is caused by the gram-negative rod Actinobacillus Iignieresi. A number of cases of abscesses affecting the face may be encountered when sheep graze pastures containing spiky plants. Unlike CLA, the lesions are in the skin rather than in the parotid or submandibular lymph nodes.

2 Are there any consequences to this infection? Enlargement of the retropharyngeal lymph nodes may compress the larynx, causing stertor, but this is rare.

3 How is the diagnosis confirmed? Diagnosis is based on clinical findings and confirmed following bacterial culture.

4 What treatment(s) are necessary? When confined to the subcutaneous tissue of the face, the abscesses cause few problems. Antibiotic therapy is not necessary, nor would antibiotics penetrate the fibrous capsule of these abscesses. Lancing such abscesses is not necessary, as they will eventually discharge themselves, and is contraindicated in countries with endemic CLA in case the skin lesions are caused by CLA, with consequent environmental contamination.

Sheep with stertor caused by compression of the larynx associated with enlargement of the drainage retropharyngeal lymph nodes should be treated with a soluble corticosteroid to reduce associated swelling and procaine penicillin (15 mg/kg daily for at least 10 consecutive days) (time-dependent antibiotic).

CASE 2.4

1 What conditions would you consider? The most likely conditions to consider include: adenocarcinoma of the small intestine with transcoelomic spread impairing lymphatic drainage and causing ascites; ascites as a consequence of low serum albumin concentration (e.g. chronic paratuberculosis); ascites as a sequela to right-sided heart failure; chronic fasciolosis, but only one sheep affected; chronic peritonitis.

2 What further tests would you undertake? Serum protein analysis reveals marginally low albumin concentration (26 g/l [2.6 g/dl]) but normal globulin concentration (46 g/l [4.6 g/dl]). There is no evidence of either a protein-losing enteropathy (such as paratuberculosis) or chronic bacterial infection from these serum protein concentrations. Peritoneal fluid analysis reveals a modified transudate (protein concentration 34.8 g/l [3.48 g/dl]) with a large number of carcinoma cells on cytospin.

3 What is your diagnosis, and what treatment would you administer? Euthanasia for welfare reasons is indicated after the diagnosis of adenocarcinoma of the small intestine. Necropsy reveals a large tumour with transcoelomic spread to the omentum, abdominal wall, liver and diaphragm (2.4b). Blockage of lymphatic drainage led to the ascites observed in this case.

4 What is the likely cause? An association with bracken ingestion has been suggested but is unproven; this sheep had no access to bracken.

CASE 2.5

1 What is your provisional diagnosis (most likely first)? The most likely conditions to affect individual sheep include: Johne’s disease (paratuberculosis); subacute fasciolosis - these sheep may not have been drenched correctly; haemonchosis - these sheep may not have been drenched correctly; chronic suppurative pneumonia or other septic focus; poor molar dentition; intestinal tumour.

2 What tests would you undertake? Sheep with advanced Johne’s disease have profound hypoalbuminaemia (serum values 30 g/l [3 g/dl]) and normal globulin concentration, but these protein concentrations may very occasionally be encountered in cases of severe chronic parasitism. Typically, in chronic fasciolosis and chronic bacterial infection there is hypoalbuminaemia (55 g/l [5.5 g/dl]; normal range 1.0 g/l [0.1 g/dl]). Muscular dystrophy causes a >100-fold increase in serum creatine kinase concentration.

3 What treatments would you administer? There is a rapid and dramatic response to IV dexamethasone and IM procaine penicillin injections such that lambs are ambulatory 6-12 hours later (2.7b). Procaine penicillin remains the drug of choice for all streptococcal infections in farm animals (amoxicillin/clavulanic acid combination is not necessary). Procaine penicillin (15 mg/kg IM) should be administered for a further 5-10 consecutive days.

4 What preventive measures could be adopted? The shepherd had immersed the lambs’ navels in strong veterinary iodine on three occasions within the first 6 hours of life. Hygiene measures in the lambing shed and ensuring passive antibody transfer often fail to reduce ongoing problems of S. dysgalactiae polyarthritis. In this situation it was suggested that the S. dysgalactiae bacteraemia arose from

either the lamb's upper respiratory tract or tonsils because there was no gross evidence of omphalitis. Changing the lambing accommodation is rarely possible other than turning housed ewes out to pasture, but this increases the risk from hypothermia and causes difficulty catching ewes with problems such as dystocia.

The prevalence of polyarthritis caused by S. dysgalactiae may become so high that it justifies metaphylactic penicillin injection when the lambs are turned out to pasture with their dam at 24-48 hours old, but this practice is not consistent with good clinical practice and responsible use of antibiotics.

CASE 2.8

1 Interpret the important sonographic features. There is a large accumulation of fluid in the abdominal cavity with dorsal displacement of viscera. There are no fibrin tags, therefore the fluid would likely be a transudate.

2 What is your provisional diagnosis (most likely first)? Include: ascites associated with Johne's disease (paratuberculosis); ascites associated with intestinal adenocarcinoma; fasciolosis; ascites associated with haemonchosis; right-sided heart failure.

It is not possible to differentiate the cause of ascites from ultrasound examination alone; ultrasound measurement of ileal wall thickness is not sufficiently accurate to diagnose paratuberculosis; identification of a 3-5 cm mass would be suggestive of an intestinal adenocarcinoma. In this situation, paratuberculosis would be the more likely diagnosis because of high annual losses from similar cases, although necropsy confirmation is important for future control advice.

3 What further tests would you recommend? Sheep with advanced Johne's disease have profound hypoalbuminaemia (serum values 30 g/l [3 g/dl]), but obvious ascites is unusual. Adenocarcinoma can also lead to a protein-losing enteropathy. ELISA tests for Johne's disease have a high specificity but low sensitivity; the advanced nature of lesions in this sheep would very likely lead to a positive result. Faecal PCR testing is also possible for Johne's disease but is more expensive. Necropsy reveals serous atrophy of fat, thickening of the ileal wall and enlargement of mesenteric lymph nodes (2.8b), consistent with Johne's disease.

4 What action would you take? Explore the potential economic benefits of vaccination; increased production and reduced mortality must be balanced against the cost of vaccination.

CASE 2.9

1 How would you interpret the necropsy results? Necropsy of six sheep is expensive and fails to give any meaningful information regarding disease prevalence in a 2,400 ewe flock.

2 What advice would you offer? A visit to the farm is essential and reveals that many of the ewes that die show vague respiratory signs of exercise intolerance and increased respiratory rate, but these observations have been largely ignored because the ewes appeared bright and alert with a normal appetite before death. Fifty-eight sheep in poorer condition were separated from the main flock at shearing time and made available for veterinary examination. Transthoracic ultrasonography takes less than 2 hours and seven of the 58 sheep are identified with OPA; examination at the slaughter plant confirms the diagnosis in all cases. (Note: These animals were sold for slaughter, thereby generating income for the farmer.)

The major risk for OPA is housing, with transmission spread via fomites. There is a cost involved in scanning all breeding stock, but this is offset by selling all OPA- positive cases immediately for slaughter rather than be collected later as cadavers. Culling OPA cases as early as possible greatly reduces disease transmission and mortality over the coming years compared with instituting no control measures at all.

CASE 2.10

1 What conditions would you consider? The most likely conditions to consider include: compressive cervical myelopathy (CVM); cervical vertebral empyema; cerebellar abiotrophy.

2 What further tests could be undertaken? In CVM cases, CSF specific gravity, total protein content, and cell count are within normal ranges. Radiographic examination of the cervicothoracic vertebral column fails to demonstrate any gross bony abnormalities; however, radiographic myelograms have revealed extradural lesions at the level of C6-C7, where the dorsal contrast column ends abruptly.

Postmortem examination of the two rams reveals discrete, smooth, nodular to polypoid projections of adipose tissue prolapsing through the dorsolateral intervertebral space at C6-C7, causing localised spinal cord compression. Histopathology of the nodules confirms that they are composed of well-differentiated adipocytes typical of fatty tissue. There is marked Wallerian degeneration at the site of compression, with milder changes present cranial and caudal to the lesion.

3 What actions/treatments would you recommend? The rams should be culled for welfare reasons.

4 What control measures could be taken? CVM has been recognised in Texel and Beltex sheep and is related to particular bloodlines. Affected rams must not be used for breeding in purebred flocks; there are no reports of this condition in crossbred sheep.

CASE 2.11

1 What conditions would you consider? Basillar empyema; listeriosis.

Listeriosis is the primary differential diagnosis because of involvement of multiple CNs, but it is unusual to find bilateral CN deficits in lambs more than 3-4 months old. A lack of menace response would be unusual in listeriosis.

2 What is the cause of this condition? Localised infection of the frontal sinuses is considered to be one source of haematogenous spread to the rete mirabile (a complex of blood capillaries surrounding the pituitary gland) extending into the cranial cavity and

along the floor to affect CNs II-VII. Typical necropsy findings are shown (2.11b); note the purulent exudate on the surface of the brain in relation to the CN roots, which further explains the clinical signs. This route of infection may be supported by the mucopurulent nasal discharge. Radiography is unlikely to detect superficial infection of the frontal sinuses. The prevalence of basilar empyema is not known because it is commonly mistaken for listeriosis. Fighting

injuries causing infected head wounds may explain the more common occurrence in rams. Nose rings in bulls are a common source of such infection in cattle.

3 What treatment would you administer? The treatment protocol comprises an extended course of procaine penicillin (15 mg/kg IM daily) and a single injection of dexamethasone (1 mg/kg) on the first day of antibiotic therapy.

4 What is the prognosis for this lamb? The advanced pathology at presentation, and lack of drainage from within the cranium, suggests a guarded prognosis. The lamb should be euthanased for welfare reasons if there is no dramatic improvement within 2-3 days.

CASE 2.12

1 Where is the probable site of the lesion? Between C6 and T2.

2 What type of lesion would you suspect (most likely first)? Include: vertebral empyema; sarcocystosis; bilateral fore leg lameness/polyarthritis.

3 What further investigations could be undertaken? Lumbosacral CSF analysis is a sensitive and specific test for an inflammatory lesion causing spinal cord compression, with an increase in lumbar CSF protein concentration from a normal concentration 1.0 g/l (0.1 g/dl), and frequently >2.0 g/l (0.2 g/dl). There is little increase in the white cell concentration. Radiographic identification of vertebral empyema is difficult even with excellent quality radiographs. Myelography can be performed under general anaesthesia, but is expensive and cannot be justified. The lesion can be confirmed at necropsy by longitudinal section of the vertebral column (2.12b, arrow).

4 What prognosis would you offer? Compressive spinal cord lesions,

whether traumatic or infectious in origin, offer a grave prognosis and euthanasia is indicated for animal welfare reasons.

CASE 2.13

1 What action would you take? First consider injection of a NSAID IV to reduce pain, although there is no published evidence at present. (Note: Off-label use in many countries.) Extradural xylazine is the better option.

Repulsion of the lamb’s head is greatly facilitated after sacrococcygeal extradural lidocaine injection, which blocks the reflex abdominal contractions of the ewe. The more traditional way of repelling a lamb is to enlist the help of an assistant, who suspends the ewe by the hindlegs while the lamb is forced back against the ewe’s strong abdominal contractions. This procedure causes considerable distress to the ewe because the weight of the pregnant uterus, rumen and other abdominal viscera are forced against the diaphragm. The risk of trauma to the uterus and vagina are greatly increased if the lamb is forced back into the body of the uterus against such powerful opposition.

The first intercoccygeal space is identified by digital palpation during slight vertical movement of the tail, and a 40 mm (1.6 in) 19 gauge needle directed at 20° to the tail, which is held horizontally. Correct positioning of the needle is determined by the lack of resistance to injection of 0.5-0.6 mg/kg of 2% lidocaine and 0.07 mg/kg xylazine (Note: off-label use in many countries) equivalent to 2 ml of 2% lidocaine solution and 0.25 ml of 2% xylazine solution for an 80 kg ewe, respectively.

Correction of this malposture involves repulsion of the head into the vagina, flexing the shoulder and elbow joint of one fore leg, and then carefully

extending the carpus (knee) and fetlock joint in that order, which presents the foot at the pelvic inlet. These manipulations are then repeated for the other fore leg (2.13b).

The lamb’s head and tongue may remain swollen for a few hours and it is prudent to stomach tube the lamb to ensure that it receives sufficient colostrum (50 ml/kg within the first 2 hours; do it immediately and the task is not forgotten).

CASE 2.14

1 What conditions would you consider? Closantel toxicity; polioencephalomalacia (PEM); basillar empyema.

Closantel toxicity can occur at a low incidence after slight overdosing. The speed of onset and severity of clinical signs appears to be dose dependent. Clinical examination, particularly the lack of pupillary light reflexes, and history narrowed the list of differential diagnoses, with closantel toxicity considered the most likely; pituitary tumours would be unlikely to affect several sheep simultaneously. Sheep affected by PEM have intact pupillary light reflexes. Ovine pregnancy toxaemia would not affect single-bearing and barren ewes.

2 What treatment would you administer? There is no effective treatment for closantel toxicity. Histopathology revealed extensive loss of nerve structure and replacement with fibrosis in the intracanalicular section of the optic nerve. Within the retina there was diffuse loss of the ganglion cell layer and thinning of the photoreceptor layer, especially in the non-tapetal retina.

3 What is this significance of this outbreak? The greater geographical range of Fasciola hepatica and the increased incidence of triclabendazole resistance is likely to lead to increased closantel use. Therefore, practitioners should advise clients to limit overdosing by dividing sheep into narrow weight categories at the time of dosing, and be aware of the clinical signs of closantel toxicity.

CASE 2.15

1 What conditions would you consider (most likely first)? Include: carpal hygroma; infected tendon sheath.

2 What further examinations would you take? The carpal swellings are soft, non­painful and restricted to the dorsal aspect of the carpus, thereby consistent with a carpal hygroma. The overlying skin is thickened, with loss of hair. Hygromas can become large (2.15b) but do not cause lameness. This condition, although generally bilateral, is common in rams as a consequence of chronic foot lameness (footrot) and long periods spent grazing on their knees. Attempted drainage would be cavalier and unjustified because of the risk of introducing infection. Ultrasonographic examination of any soft tissue swellings using a 5 or 7.5 MHz linear scanner could be undertaken but is not necessary.

3 What advice would you offer? Carpal hygromas indicate a prolonged period of fore leg lameness and ideally this ram should not have been purchased. Prompt attention to lameness will prevent the development of hygromas.

CASE 2.16

1 What pathogens could be involved? Gangrenous mastitis caused by Mannheimia spp. and Staphylococcus aureus occurs sporadically during the first 2 months of lactation associated with poor milk supply related to ewe undernutrition and overvigorous sucking by the lambs. Gangrenous mastitis is often preceded by either staphylococcal or orf skin lesions of the ewe's teat. It is most commonly reported in ewes nursing twins or triplets.

2 What is the prognosis? Despite antibiotic and supportive therapy the prognosis is grave and the gangrenous udder tissue eventually sloughs, leaving a large granulating surface with superficial bacterial infection. Superficial trauma readily causes bleeding. The granulation tissue continues to proliferate (2.16b) over the coming months (up to 10-20 cm in diameter) and affected ewes cannot be presented at markets. It is unusual for these lesions to suffer from cutaneous myiasis, but affected sheep are greatly worried by nuisance flies if kept outdoors during the summer and lose a great deal of body condition.

3 What action would you take? These ewes are unsuitable for breeding stock. The infected granulation tissue, and resultant deep inguinal lymph node enlargement, would result in carcass condemnation (and raise genuine welfare concerns). The fleece is very poor because growth has occurred during this period of illness and debility. The ewe should be euthanased for welfare reasons at first presentation.

4 What control measures could be adopted? Control measures include ensuring ewes are well fed. Supply concentrates to ewes and lambs when pasture is poor. Do not expect any ewe to rear triplets. Identify and treat superficial teat lesions with topical antibiotics. Control of orf by skin scarification using live virus vaccine remains largely unproven but is commonly practised.

CASE 2.17

1 What is your diagnosis? The most likely conditions to consider include: visceral caseous lymphadenitis (Corynebacterium pseudotuberculosis; CLA); abscess; tuberculosis.

The lamellar appearance of the mediastinal lymph node is typical of visceral CLA. Bacteriology could be undertaken to confirm the diagnosis. Scotland is officially free of bovine tuberculosis.

2 What action would you take? This ram had been purchased 4 years ago and no discharging skin lesions have been noted in the ram group or the flock in general. All other rams in the group are in good body condition. It is likely that the ram had the lesion at the time of purchase and the risk of spread within the group is low. The farmer is advised about the appearance of the cutaneous form CLA (discharging lesion most often involving the parotid lymph node) and to submit any other lean rams for veterinary examination. Serological testing of the ram group could be undertaken, but the farmer was unwilling to cull a fit ram simply on the basis of a seropositive result.

3 What control measures should be adopted in this flock? Strict biosecurity measures with quarantine of all purchased stock, especially rams, is strongly recommended to prevent introduction of many contagious diseases, including CLA, but are not rigorously applied on most UK sheep farms. Visceral CLA is an uncommon cause of emaciation of adult sheep in the UK, a situation that differs from many other countries including the USA and Australia. Commercial interests in promoting CLA control in the UK have deflected resources from other more important diseases such as ovine pulmonary adenocarcinoma and paratuberculosis. CLA is not a major concern for commercial sheep farmers in the UK; strict segregation of affected sheep where it does arise may be all that is required. CLA control in pedigree ram studs, which are housed for long periods and maintained tightly stocked, is more problematic. While this ram would have tested positive for CLA, such infection did not affect its productive life.

CASE 2.18

1 What conditions would you consider (most likely first)? Include: trace element deficiency, particularly cobalt and selenium deficiency; poor grazing; poor parasite control.

2 How would you investigate this problem? Faecal worm egg counts from ten lambs average 100 strongyle epg (no treatment necessary). Serum vitamin B₁₂ concentrations from six lambs reveal very low concentrations (mean preparations, or at inclusion rates of 15-30 g per 10 litres of 2.25% benzimadazole or 1.5% Ievamisole drench); however, anthelmintic treatment is not indicated at the present time in these lambs on safe grazing.

CASE 2.19

1 What common problems would you consider (most likely first)? The most likely conditions to consider include: coccidiosis; cryptosporidiosis; Strongyloides papillosus infection; salmonellosis.

2 How could you confirm your provisional diagnosis? The clinical signs are suggestive of coccidiosis. Oocyst counts can be variable but are usually very high in lambs scouring for more than several days. Identification of the pathogenic species Eimeria ovinoidalis or E. crandallis is rarely undertaken. Gut smears and histopathology of gut sections are taken from dead lambs. The response to treatment for coccidiosis helps confirm the diagnosis.

3 What treatment would you administer? Treatment options include a single drench with either toltrazuril or diclazuril, or decoquinate added to the lambs’ concentrate ration, which can be used as a treatment/preventive measure. Where doubts exist over feed intake, toltrazuril or diclazuril is the treatment

of choice. The feeding areas and water trough area can become very heavily contaminated even when lambs are reared outdoors (2.19b), therefore the lambs should be moved to a clean pen/ field immediately.

Medication of the ewe ration with decoquinate will suppress but not totally eliminate oocyst production, therefore this regimen is operated in conjunction with medication of the lamb creep feed.

CASE 2.20

1 What conditions would you consider? The most likely conditions to consider include: contagious ovine digital dermatitis; footrot; white line abscess extending to the coronary band; shelly hoof.

2 What is the likely cause? Contagious ovine digital dermatitis is the most likely cause of lesions originating at the coronary band and causing sloughing of the entire hoof capsule. There is no ready explanation why only one digit of one foot is affected.

3 What action would you take? Isolate all affected lame lambs. Inject all lame lambs with a single injection of tilmicosin or gamithromycin (note off-label use in many countries); oxytetracycline may also be effective. Spray with topical oxytetracycline aerosol. Long-acting amoxycillin has also been shown to be effective but has not been directly compared with a macrolide antibiotic. Convalescence is protracted, especially when the hoof capsule has been shed (2.20b; note that both hoof capsules have been shed from the foot on the right-hand side of this image).

4 How could this condition be prevented? Strict biosecurity should help prevent introduction of the disease. Hoof knives can transmit the causal organism of digital

dermatitis between cattle, and this seems likely in sheep as well. Prompt attention (antibiotic injection) to all lame sheep may prevent such advanced painful lesions. Metaphylactic injection could be considered in other sheep in the group.

CASE 2.21

Describe the method you would use to collect CSF from an obtunded sheep. For CSF collection it is necessary to puncture the subarachnoid space in the cerebellomedullary cistern (cisternal sample) or at the lumbosacral site (lumbar sample). In the absence of a focal spinal cord compressive lesion, there is usually no substantial difference between the composition of cisternal and lumbar CSF samples; there are few indications for cisternal collection.

Collection of lumbar CSF is facilitated when the animal is positioned in sternal recumbency with the hips flexed and the hindlegs extended alongside the abdomen. Aversion of the head against the flank may assist in maintaining sternal recumbency during the CSF collection procedure. Sedation of the animal is not usually necessary but can be achieved using 10 μg∕kg detomidine injected IV (note off-label use in some countries). Xylazine (0.04-0.07 mg/kg IV) produces very variable sedation and is not recommended.

The site for lumbar CSF collection is the midpoint of the lumbosacral space (2.21), which can be identified as the midline depression between the last palpable dorsal lumbar spine (L6) and the first palpable sacral dorsal spine (S2). The site must be clipped, surgically prepared and between 1 and 2 ml of local anaesthetic injected SC. An internal stylet is not required (see Guide below). The needle is

slowly advanced at a right angle to the plane of the vertebral column or with the hub directed 5° caudally. It is essential to appreciate the changes in tissue resistance as the needle point passes sequentially through the subcutaneous tissue, interarcuate ligament then the sudden ‘pop’ due to the loss of resistance as the needle point finally penetrates the ligamentum flavum into the extradural space. Once

the needle point has penetrated the dorsal subarachnoid space, CSF will well up in the needle hub within 2-3 seconds.

One to 2 ml of CSF is sufficient for laboratory analysis and while the sample can be collected by free flow, it is more convenient to employ gentle syringe aspiration over 10-30 seconds. Care must be taken not to dislodge the needle point from the dorsal subarachnoid space when the syringe is attached to the needle hub. Stabilising the position of the needle can be assisted by firmly resting the wrist on the sheep’s vertebral column.

Guide to needle length and gauge for lumbar CSF sampling.

CASE 2.22

1 What conditions would you consider? The most likely conditions to consider include: chronic copper poisoning; chronic fasciolosis; sulphur toxicity/ polioencephalomalacia.

2 What further tests could be undertaken? Tests for chronic copper toxicity could include serum liver enzyme assays such as GGT and AST concentrations, which are increased 10-50-fold, indicating severe liver damage. The serum copper concentration may not be elevated above the normal range in toxicity cases.

3 What actions/treatments would you recommend? Where available, the treatment plan could include 1.7 mg/kg ammonium tetrathiomolybdate given by slow IV infusion on two occasions 2 days apart (or 3.4 mg/kg injected SC). Three litres of 5% glucose saline can be given IV over 6 hours where cost permits. Oral fluids

could be administered, but the prognosis is guarded and euthanasia is the humane option.

This ram should be euthanased for welfare reasons and the provisional diagnosis confirmed at necropsy, where there is jaundice of the carcass, most noticeable in the omentum. The kidneys are swollen and dark grey (2.22b), with dark red urine in the bladder.

The liver is enlarged and friable. The kidney copper concentration is massively elevated (10-20-fold above normal value of control congenital swayback). No additional source of copper had been administered to this group. Copper antagonists, such as molybdenum, may be required when susceptible breeds are fed high levels of concentrates (especially when rearing studs rams and feeding high levels of supplementary concentrates) despite the content not exceeding 15 mg/kg copper as fed. No extra source of copper was found in this situation and accumulation over time at pasture was considered to be the likely source, but was not proven. Adding a copper antagonist, such as molybdenum, to the ration was recommended. A change of breed should be considered if the problem continues.

CASE 2.23

1 What is the cause of this problem (most likely first)? Several causes in cattle have been suggested such as pharyngeal or reticular irritation, highly acidic rations, vagus indigestion, and high intraruminal pressure. There was no evidence of any of these problems. Rhododendron poisoning is a common cause of acute vomiting in sheep, but there is an obvious source.

2 What action would you take? Without a specific diagnosis, there is no specific treatment.

3 How could you confirm the cause? Necropsy of this case failed to identify any anatomical abnormality.

4 Is this condition heritable? It is not known whether this condition is heritable but it would be prudent not to breed from affected rams. Few farmers keep adequate records to look at the potential heritability of this condition.

CASE 2.24

1 Describe the important postmortem features. The liver is grossly enlarged with multiple haemorrhagic tracts visible under the liver capsule and throughout its substance on cut surface. There is a large amount of organised fibrin on the liver capsule.

2 What is the most likely cause? Severe subacute fasciolosis (Fasciola hepatica infection).

3 How could this problem be confirmed in other sheep in the group? Clinical disease is apparent before liver flukes become patent, so a sedimentation test on a faecal sample will not help. Subacute fasciolosis can be diagnosed by the coproantigen ELISA test. Raised serum AST and GLDH concentrations indicate liver damage, but are not pathognomonic for fasciolosis. Increased serum GGT concentrations, which indicate bile duct damage, are also commonly used to aid diagnosis. These three liver enzymes are typically increased by 5-30-fold but, in the case of AST, fall to near normal concentrations within 10-14 days of flukicide treatment. Serum GGT and GLDH remain elevated for at least 1 month after flukicide treatment.

The serum albumin concentration is reduced to 12-20 g/l (1.2-2.0 g/dl) and the serum globulin concentration is massively increased to >65 g/l (6.5 g/dl) and often >75 g/l (7.5 g/dl). There are few bacterial infections that give such a dramatic serum protein profile, and certainly none on a group basis; therefore, serum protein analysis should be included with liver enzymes in the biochemistry profile.

4 What action would you take? Triclabendazole is effective at killing all fluke stages. Drenched sheep should be moved to clean pasture. Re-treatment should be based on risk and may be necessary 3-6 weeks after the first treatment in high risk years where there is no alternative pasture or housing. Thereafter, treatment with closantel should be considered to avoid selecting for triclabendazole resistant strains of liver fluke, but noting that closantel is only effective against developing flukes more than 7-8 weeks post ingestion of metacercariae.

CASE 2.25

1 What conditions would you consider (most likely first)? Dermatophilosis; staphyloccocal dermatitis; psoroptic mange; ringworm.

2 What further tests could be undertaken? Diagnosis of dermatophilosis is based on clinical examination and, if necessary, stained smears from the underside of scabs plucked from the fleece, which reveal coccoid bacteria. Bacteriology is rarely undertaken.

3 What actions/treatments would you recommend? Treatment is rarely indicated, but rams intended for sale are sometimes treated to prevent skin lesions regrowing discoloured wool, which is considered a cosmetic defect at sale. Procaine penicillin (15 mg/kg IM for 3 consecutive days) effects a cure but it may take several weeks for the scabs to be shed from the growing fleece.

4 What control measures could be taken? A variety of dip solutions have been used in New Zealand and Australia to prevent dermatophilosis following shearing, including 1% potassium aluminium sulphate spray or dip solution. Dermatophilosis is rarely a disease of well-fed sheep; severe disease occurs only in sheep debilitated from another cause, in this case paratuberculosis.

CASE 2.26

1 What conditions would you consider (most likely first)? Include: pleuropneumonia/ pleural abscess occupying the right chest; transudate/exudate occupying the right chest; chronic suppurative pneumonia; diaphragmatic hernia; ovine pulmonary adenocarcinoma (OPA); mediastinal abscess caused by caseous lymphadenitis (CLA); visna-maedi.

2 How would you investigate this problem further? Ultrasonographic examination of the chest will allow diagnosis of any respiratory condition, such as pleural abscess/pyothorax or OPA. Note that these respiratory conditions can be largely unilateral. The production of copious clear frothy fluid from nostrils when the ewe's hindquarters are raised (positive wheelbarrow test) is also pathognomic for advanced cases of OPA, but this greatly exacerbates any dyspnoea such that affected sheep should be killed immediately afterwards for welfare reasons. Note that not all OPA cases produces significant fluid.

chest revealed normal lung with the heart pushed against the chest wall. A standing lateral radiograph of the right chest showed a fluid line consistent with a diagnosis of diaphragmatic hernia.

3 What treatment would you administer? The prognosis for diaphragmatic hernia is hopeless and the sheep was killed immediately for welfare reasons.

4 What is the likely cause? The cause of this case of diaphragmatic hernia was not established. There

The ultrasound image of the right chest showed small intestine (2.26b) consistent with a diagnosis of diaphragmatic hernia. Sonograms of the left was no history of severe trauma such as a road traffic accident. This was the second case from this flock of 600 breeding sheep in 2 years.

CASE 2.27

1 What conditions would you consider (most likely first)? Elbow arthritis; osteoarthritis of the elbow joint.

Arthropathy of the elbow joint in adult sheep is characterised by extensive enthesophyte formation involving the lateral ligament (Lig. collaterale ulnae) following trauma to the mechanism preventing overextension of the elbow joint. Enthesitis is a term used to describe changes occurring at the insertion of a muscle, tendon, ligament or articular capsule where recurring concentration of stress provokes inflammation, with a strong tendency towards fibrosis and calcification. The elbow joint is a typical ginglymus joint, with movements restricted to flexion and extension. The lateral ligament of the elbow is short and strong, and along with tension in the medial collateral ligament and biceps brachii muscle, is largely responsible for limiting the degree of extension of the elbow joint.

2 What further tests could be undertaken? An oblique radiograph of the right elbow (2.27b) reveals the characteristic enthesophytic reaction where the two advancing edges are clearly visible.

3 What actions/treatments would you recommend? There is no effective treatment; short-term pain relief (NSAID injection) may be effective but there are no long-term treatment options.

4 What control measures could be taken? Avoid stress/trauma to the elbow joints when performing tasks such as casting, but this is not always easy to achieve. Do not feed young rams excessively to achieve maximum growth rate.

CASE 2.28

1 What conditions would you consider (most likely first)? Partial obstructive urolithiasis; cystitis.

2 What further investigations could be undertaken? Transabdominal ultrasound examination of the right kidney in the right flank can be undertaken to check for hydronephrosis, but may not be necessary because of the relatively short duration of urethral obstruction. Blood urea nitrogen and creatinine concentrations are increased 5-20-fold.

3 What action would you take? The ram should be cast onto its hindquarters and the penis extruded to examine the vermiform appendage (2.28b) by straightening the sigmoid flexure. When present, a calculus can be felt within the tip of the vermiform appendage, which is excised with a scalpel blade. After the ram is allowed to stand, a continuous flow of urine is often voided. The ram must be carefully observed for normal urination and appetite over the next few days in case other calculi block the urethra. Spasmolytics (hyoscine) and corticosteroids are often administered but their value remains unproven.

4 What sequelae could result in neglected cases? Early recognition of

urethral obstruction is essential because irreversible hydronephrosis develops after approximately 5-7 days due to back pressure within the urinary tract. Re-blockage with further calculi is possible. A tube cystotomy can be undertaken in valuable breeding rams with proximal urethral obstruction. As a salvage procedure, a subischial urethrostomy can be performed under caudal block, but this is not a simple procedure and must be carefully considered because ascending infection of the transected urethra is inevitable.

5 What control measures would you recommend? Control of urolithiasis (struvite crystals) involves feeding a correct ration with a low magnesium content. The salt concentration of the ration can be increased to increase water intake and urine output. Urine acidifiers such as ammonium chloride can also be added to the ration. Good quality roughage should be available ad libitum.

CASE 2.29

1 What conditions would you consider (most likely first)? Include: bacterial endocarditis; septic polyarthritis; bluetongue.

2 How could you confirm your diagnosis? Despite vegetative lesion(s) on the heart valve(s), auscultation of both cattle and sheep with vegetative endocarditis often fails to reveal abnormal heart sounds, but the heart rate is usually increased and irregular. Ultrasound examination of the heart with a 5 MHz sector scanner can identify a classical vegetative growth in some cases (2.29b, arrow). Arthrocentesis would differentiate joint effusion from sepsis but most joint exudate forms a pannus.

3 What treatment would you administer? Antibiotic therapy with daily penicillin injections can be attempted, but the response is hopeless because of the advanced nature of the heart valve lesions when presented for veterinary examination. Temporary improvement with reduced joint distension follows a single dexamethasone injection in most cases, but lameness returns within 4-7 days.

4 What action would you recommend? The sheep should be euthanased for welfare reasons.

Large vegetative lesions were demonstrated on the mitral valve of this ram. Foci are commonly observed in the kidneys.

5 What control measures would you recommend? A primary focus of infection is rarely found at necropsy of adult sheep. Bacterial endocarditis in ewes often occurs 2-3 months after lambing; improved hygiene and prompt treatment of metritis may reduce potential bacteraemia and subsequent endocarditis. In lambs, bacterial endocarditis is occasionally associated with Erysipelothrix rhusiopathiae infection.

CASE 2.30

1 What conditions would you consider (most likely first)? Include: entropion; infectious keratoconjunctivitis; congenital microphthalmia.

2 What treatments would you administer? Treatment involves eversion of the lower eyelid as soon after birth as possible, with regular inspection to ensure it and requires only one operator. Skin suture(s) can be inserted to evert the lower eyelid but this procedure requires two people, one to restrain the lamb and the other to carefully insert the suture.

remains everted. Topical antibiotic application controls secondary bacterial infection and aids movement of the lower eyelid, thereby reducing the likelihood of inversion.

Subcutaneous antibiotic injection (1 ml of procaine penicillin) can be used to evert the lower eyelid (2.30b). Eales clip(s) can be inserted in the skin below the lower eyelid to cause eversion

3 What are the consequences of no action/treatment? Include rupture of the cornea with herniation of the lens and loss of the eye in neglected cases.

4 What preventive measures could be adopted? Entropion has a high hereditary component and rams siring affected progeny should be culled, but this rarely occurs.

CASE 2.31

1 What conditions would you consider? Include: infectious polyarthritis caused by Erysipelothrix rhusiopathiae; infectious polyarthritis secondary to tick-borne fever; bacterial endocarditis.

2 What is the likely cause? Streptococcus dysgalactiae affects lambs within the first 2 weeks of life, while E. rhusiopathiae tends to affect lambs from 2 weeks old.

3 How would you confirm the cause? Samples of synovial membrane from sacrificed untreated cases are preferable to joint aspirates for bacteriological examination. Note that there can be a high seroprevalence to erysipelas in normal healthy sheep.

4 What treatment would you administer? While aggressive penicillin therapy during the early stages of infection effects a good cure rate in many E. rhusiopathiae infections, and may render the joints sterile, some infections are not cleared, with the result that progressive and degenerative changes occur within the joint. Indeed, dead bacteria and white blood cells within the joint induce inflammatory changes including proliferation of the synovial membrane and fibrous thickening of the joint capsule. Note that inflammation of the synovium gives the infected joint a pink colour compared with white in the normal joint (inflamed synovium shown in the left-hand stifle joint in 2.31b; right-hand side stifle joint is normal). Such joint pathology will not respond to further antibiotic therapy and these lambs should be euthanased for welfare reasons.

5 What control measure(s) would you recommend? Where available, vaccination of the dam with effective passive antibody transfer protects lambs from erysipelas for up to 4-6 months.

CASE 2.32

1 Describe the major radiographic changes. Radiography reveals extensive bone lysis of the femoral head and acetabulum extending to involve the shaft of the ilium. The true extent of bone destruction is best illustrated in ‘boiled out’ preparations (2.32b, c).

2 What is the likely cause? The septic hip joint probably arose from infection of the proximal femoral growth plate following haematogenous spread. The true incidence of septic physitis is unknown because few lambs are necropsied and it is generally assumed that all chronic severe lameness is caused by joint infection.

3 What treatment would you recommend? The lamb must be euthanased immediately for welfare reasons. This lamb has suffered unnecessarily and the farmer must be made aware of this serious welfare concern.

CASE 2.33

1 Describe the sonogram. The broad hyperechoic line present dorsally represents the lung surface (visceral pleura), which is displaced from the chest wall by an extensive hypoechoic area, with a slightly hyperechoic latticework matrix typical of a fibrinous pleurisy extending to 8 cm deep at the ventral margin.

2 What is your diagnosis? The sonographic findings are consistent with a diagnosis of extensive fibrinous pleurisy of the left chest.

3 What treatment(s) would you administer? There are no reports of diagnosis/successful treatment of such lesions in sheep. The ram was treated with procaine penicillin (15 mg/kg IM daily for 4 weeks) and made a good recovery. After 2 months, the pleural lesion comprised a 5 cm diameter organised fibrin clot (2.33b).

4 What is the origin of this pleurisy? Streptococcus dysgalactiae has been isolated from pleurisy lesions in ewes that had numerous large abscesses within the udder parenchyma. The potential source of infection in this ram was not identified.

CASE 2.34

1 Describe the important sonographic findings. The large anechoic area, extending for up to 16 cm, represents fluid distension of the abdomen, with the liver and omentum displaced dorsally. There are numerous large fibrin tags (inflammatory exudate) on the liver capsule extending to the omentum, gallbladder, liver lobe and body wall. The liver is not homogeneous but contains many hyperechoic dots, consistent with inflammatory cell accumulations caused by migrating immature flukes.

2 What tests would you undertake? Abdominocentesis would establish whether the fluid was a transudate or an inflammatory exudate (>30 g/l [3 g/dl]; more likely due to fibrin present).

3 What causes would you consider? The fibrin tags on the liver, and to the adjacent viscera/body wall (2.34b), would be consistent with severe subacute fasciolosis and this would indicate late season metacercariae ingestion.

Other conditions to consider include: diffuse peritonitis

associated with liver infection (abscessation), although none apparent; ascites associated with transcoelomic spread of small intestine adenocarcinoma, but contains no fibrin tags; uroperitoneum, but has never been reported in a ewe.

4 How would you confirm your diagnosis? Raised serum GGT and GLDH concentrations are consistent with hepatic damage caused by migrating flukes. Changes in albumin and globulin concentrations are not disease specific.

5 What treatment(s) would you administer? The prognosis for this ewe is guarded due to the well-established fibrin adhesions. Antibiotic administration and an injection of dexamethasone could be given in an attempt to treat the peritonitis, and diclabendazole given to treat immature fasciolosis.

6 Are there any control measures to recommend? Treat all sheep in the flock with triclabendazole immediately and 6 weeks later with closantel in case of triclabendazole resistance. Any fluke treatment in May will suffice because all flukes will be mature.

CASE 2.35

1 Briefly list the advantages and disadvantages of flushing. Advantages:

• Flushing for 4-6 weeks should provide for a 0.5-1.0 unit increase in condition score at mating time.

• Sheep in good body condition will be better able to survive pregnancy if nutrition is poor because of adverse weather, poor management, etc.

• Flushing increases ovulation and implantation rate and eventual preg­nancy rate.

Disadvantages:

• Fields must not be grazed for 4-6 weeks to ensure a good (8 cm) grass sward.

• Extra fertiliser may be needed, which is costly.

• Reduced grazing for weaned lambs or purchased store lambs (2.35b).

• Flushing increases ovulation and implantation rates in hybrid ewes, resulting in more triplet litters, which suffer much higher perinatal losses.

• Cost and labour involved with rearing orphan lambs.

• Twin- and triplet-bearing ewes are more prone to pregnancy toxaemia, vaginal prolapse and rupture of the prepubic tendon.

2 List the alternatives that can achieve appropriate body condition scores at mating, and more lambs. Litter size at the normal breeding season can be increased by approximately 15% by the use of melatonin implants. Flushing can ensure appropriate ewe condition score at mating but this can also be achieved by correct management after weaning.

CASE 2.36

1 Interpret the sonogram. The fluid extends for >5 cm from the abdominal wall (2.36b).

2 What is your diagnosis? This appearance would be consistent with a diagnosis of uroperitoneum.

3 What other structure(s) should be checked sonographically? Uroperitoneum associated with urolithiasis is much more common in lambs than in adult sheep. Bladder rupture is unusual and urine normally leaks across the stretched bladder wall. Detection of a distended bladder (>6-8 cm in a 25-30 kg lamb) would help differentiate uroperitoneum (highly likely) from a transudate (highly unlikely). The absence of fibrin tags rules out an exudate associated with peritonitis. The right kidney should be examined ultrasonographically for evidence of hydronephrosis via the right sublumbar fossa. An increased renal pelvis to cortex ratio indicates hydronephrosis, which develops after more than 5-7 days of urethral obstruction.

4 What further tests could be undertaken? An abdominocentesis sample with a creatinine concentration >2 times the serum concentration indicates uroperitoneum.

5 What action would you recommend? In valuable breeding rams a tube cystotomy could be attempted, but this is not a simple procedure and requires general anaesthesia and long-term case management. A subischial urethrostomy, in an attempt to salvage the carcass value of this lamb, could be undertaken but would not be financially worthwhile and would also present welfare concerns.

CASE 2.37

1 What concerns you about the ram? In-growing horns can cause problems in some sheep breeds and present as a common animal welfare issue in law courts.

2 What action would you take? A conservative length of horn tip has been removed using Gigli wire in this case (2.37b) to avoid haemorrhage and possible sensitive areas nearer the horn base. Note that the skin is broken and the horn has been causing a problem for several weeks; this situation is difficult to defend in law courts because of the chronicity of the problem. Occasionally, the horn is broken near its base and becomes misshapen, with the horn tip growing into the cheek or, sometimes, the orbit of the eye.

3 What advice would you offer the farmer? Horned sheep must be checked regularly for abnormal horn position/growth and the horn(s) removed, as in 2.37b, where problems arise.

2.38b

CASE 2.38

1 Does routine foot paring reduce lameness, especially footrot? Foot paring should only be undertaken in lame sheep where the cause of lameness is not obvious and a white line abscess or similar is suspected (2.38b). All impacted soil/foreign material is removed from the interdigital space. Grossly overgrown horn from the abaxial wall and toe of the foot of the lame leg is carefully removed with shears or a sharp hoof knife to check for a white line abscess, toe granuloma, etc. Overparing of the hoof horn of the wall (2.38a) must be avoided because this action simply transfers weight to the sole. There is no evidence that routine I foot trimming prevents footrot.

2 Are there any potential disadvantages of routine foot paring? Underrunning of the horn associated with footrot or contagious ovine digital dermatitis (CODD) is very painful and is best treated with parenteral antibiotics, such as oxytetracycline, or a macrolide drug such as tilmicosin. Field studies show that better results are achieved with tilmicosin, but this drug is restricted to veterinary administration in many countries. Other macrolide antibiotics such as gamithromycin are increasingly used for treating footrot and CODD because no such restriction applies, although there is presently no license for their use in sheep in many countries. It is essential not to damage the sensitive corium, as this will delay regeneration of epithelium and extend healing time. Exposure of the sensitive corium to irritant chemicals, such as formalin in footbaths, may result in excessive granulation tissue and the formation of a toe fibroma. Foot trimming 5-7 days later when the lesions appear less aggressive is not necessary and could delay healing.

3 What control strategies could be suggested for footrot in this flock? There are few reported split-flock trials of footrot vaccines in the UK, but there is anecdotal information that vaccination can contribute to footrot control measures in flocks.

Whole flock gamithromycin treatment has produced very encouraging results with footrot elimination and flocks have remained free of disease for up to 2-3 years at the time of publication of this book. The critical factor is that every single sheep must be treated and this appears to require veterinary attendance to ensure no sheep are left untreated.

CASE 2.39

1 What are these lesions? Healing fractures at the costochondral junctions.

2 Comment on the welfare of this lamb with respect to these lesions. These lesions are likely to have been very painful at the time of injury at delivery and for at least several weeks until full union, which is apparent in 2.39b.

3 What is the most likely cause? TraumaZfractures to the rib cage at the costochondral junctions are a risk when oversized lambs (especially singletons) are delivered in posterior presentation using excessive traction. Fractures of the ribs can severely impair respiratory function and may cause death soon after delivery. It has also been suggested that lambs that sustain rib fractures during assisted delivery are more prone to respiratory infections. Excessive traction can also cause rupture of the liver, resulting in sudden death.

4 Apart from difficulty with breathing, what other clinical signs may have been present? Radial nerve paralysis/brachial plexus avulsion may also result from excessive traction of a lamb in posterior presentation.

5 How could this problem have been avoided? Perform a caesarean operation when presented with an oversized single lamb in posterior presentation, but clients are rarely prepared to pay for surgery in commercial value sheep. An oversized single lamb in posterior presentation is the most common reason to perform a caesarean operation in pedigree meat breed sheep.

CASE 2.40

1 Describe the important sonographic findings. There is marked distension of small intestine and some accumulation of fluid between distended loops of intestine. There are no visible fibrin tags. The sonogram is only an image; observation of the intestines for 30 seconds revealed very poor propulsion of digesta through the intestines.

2 What conditions would you consider (most likely first)? Small intestinal torsion around the root of the mesentery; intussusception with distended small intestine proximal to the lesion; ileus caused by grain overload.

3 What treatment would you administer? Symptomatic treatment includes ‘shock dose’ IV fluid therapy. NSAID therapy should also be administered to control pain and likely endotoxaemia. However, these treatments will not correct the primary problem of suspected intestinal torsion and the lamb should be euthanased for welfare reasons, as surgery requires inhalation anaesthesia and a surgeon skilled in abdominal surgery. The torsion was confirmed at necropsy; a similar torsion from a yearling sheep is shown (2.40b).

4 How can this problem be avoided? Small intestinal torsion around the root of the mesentery occurs sporadically, but the creep feeding may have played a role in the aetiology with limited rumen development. The farmer reported no other cases and was not prepared to compromise lamb growth rates by limiting concentrate feeding.

CASE 2.41

1 What has happened in 2.41a? Death of a foster lamb. Fostering lambs with the aid of the dead lamb’s skin generally has good success provided there is good supervision to ensure that the lamb is sucking. Not only has the ewe’s lamb died, but also a foster lamb - this situation seriously questions the level of stock supervision on this farm.

2 Is this practice common? In most management systems there is an obvious financial advantage to be gained from ewes nursing twins rather than a single lamb. The perinatal lamb mortality rate is high in many sheep flocks and as a consequence, triplet lambs are often fostered onto those ewes that have lost a lamb, whether stillborn or died from other causes. In addition, lambs are commonly fostered onto ewes that produce a single lamb. No large surveys have been undertaken to determine the number of attempted ‘fosterings’ in lowground flocks, but are conservatively estimated at greater than 10-15%. Furthermore, this procedure is not as simple as would first appear and the long-term acceptance rate by the ewe is often less than 70%.

3 What advice must be given to farm staff? The ewe and lambs must be carefully supervised to detect early rejection such as not letting the foster lamb suck and pushing the lamb away, and vigorous head butting, which can cause severe chest trauma, and indeed death, of neglected lambs. Ewes with a foster lamb should be clearly marked and allocated to small paddocks for up to 1 week before rejoining the main flock. Adequate supervision is patently lacking in this flock.

4 Are there any alternatives to this practice? Orphan lambs can be very successfully reared on artificial rearing systems using automatic milk dispensers (2.41b), which achieve excellent growth rates and a low incidence of digestive disturbances, such as abomasal bloat and/or volvulus, but are expensive.

CASE 2.42

1 What conditions would you consider (most likely first)? Include: laryngeal chondritis; laryngeal foreign body; enlarged retropharyngeal lymph nodes compressing the pharynx/larynx; pharyngeal cellulitis/abscess caused by dosing

gun injury; pasteurellosis.

2 How could you confirm your diagnosis? Swelling of the arytenoids, with or without erosion/infection of the underlying cartilage, causing severe narrowing of the larynx can be visualised during endoscopic examination (2.42b), but this procedure should not be undertaken in severely dyspnoeic sheep. Sedation is likely to exacerbate the condition.

3 What actions/treatments would you recommend? Treatment includes 10 mg dexamethasone IV immediately to reduce laryngeal oedema. There are few data to indicate which antibiotic is most appropriate; Trueperella pyogenes is commonly isolated from lesions. Early recognition and a prolonged primary course of antibiotics are essential; the recovery rate of relapsed cases is low.

In an emergency situation it may necessary to perform a tracheostomy under local anaesthesia via a ventral midline approach in the mid-cervical region. It may prove difficult fixing the trachea to make the incision between two tracheal rings without aggravating the ram’s dyspnoea. Intranasal/ transtracheal oxygen administration via a wide bore needle can be supplied if available. Be aware that abscessation of the arytenoid cartilage(s) may be present in many relapsed cases (2.42c). No further treatment will successfully resolve this problem and euthanasia is indicated.

4 What controls measures would you recommend? Conformation and turbulent air passage through the oedematous larynx of rams approaching the breeding season leads to erosion of the lining epithelium, with secondary bacterial infection causing swelling and further narrowing of the airway. Reduce level of concentrate

feeding when preparing rams for sale. Some breeders believe that there is a strong heritable component, but there are no conclusive pedigree data because most breeders are reluctant to admit to such a problem in their stock.

CASE 2.43

1 How would you achieve effective analgesia for fracture realignment and repair? Effective analgesia can be achieved immediately after lumbosacral extradural injection, using a 21 gauge, 15 mm (5/8 in) hypodermic needle, of 3 mg/kg of 2% lidocaine (note procaine is not licensed for extradural injection) and IV injection of a NSAID such as flunixin before the procedure. There are no injectable general anaesthetic drugs licensed for use in sheep in the UK, but alphaxalone and propofol work very well.

2 How would you repair the fracture? The fracture is easily reduced and immobilised with a fibreglass cast (or similar) applied with slight flexion of the hock joint. The hock angle maintains the cast in place while the ‘Softban’ or similar padding underneath permits growth over the next 3 weeks before removal. Applying traction to the distal limb without largely ineffective and results in overextension of the hock with straightening of the leg and potential for loss of the cast within hours/days (or the cast is applied too tightly). Failure to effectively reduce a metacarpal fracture has resulted in abnormal angulation of the distal limb (valgus) and excessive callus formation (2.43b). The bone reaction (exostosis) in this case may extend over time to impact on the fetlock joint.

limb paralysis to effect reduction is cruel,

3 What other treatments would you recommend? There is the risk of bacteraemia in neonates, therefore a 10-14 day course of antibiotics is indicated as a precaution against infection of the traumatised (fracture) site.

CASE 2.44

1 What is the likely cause (most likely first)? Footrot, the term commonly used to describe the highly contagious foot disease caused by D. nodosus, with extensive under­running of hoof horn; interdigital dermatitis; contagious ovine digital dermatitis.

2 How is the diagnosis confirmed? Diagnosis is based on clinical examination with underrunning of hoof horn of the sole and extending up the wall in severe cases. A polymerase chain reaction-based assay is used to specifically identify and group D. nodosus from footrot lesions, although strain typing is rarely undertaken in practice.

3 What treatment would you administer? Foot-bathing is not an appropriate treatment for sheep with footrot, although, when used correctly, it limits the spread of the disease (2.44b). The most commonly used treatment for individual sheep with footrot is an injection of long-acting oxytetracycline (20 mg/kg IM) together with removal of all debris from the interdigital space and application of an antibacterial spray. Recent field studies have also demonstrated the efficacy of gamithromycin injection. Treatment of sheep with footrot within 3 days of onset of lameness minimises spread of the disease to other sheep. Pain relief in the form of a NSAID can also be administered where sheep are markedly lame (off-label use in many countries), but there is limited supporting evidence at present. Segregating those sheep with footrot from sound sheep at the earliest opportunity helps to reduce the spread of footrot.

4 What control measures would you include in the flock health plan? Regular foot-bathing is successful in preventing footrot and reducing the spread of footrot and will also treat interdigital dermatitis, but it is not an appropriate treatment for sheep with footrot. There is no evidence that any one type of foot-bath treatment formulation is more effective than another. There is some published information that footrot vaccination can contribute to its control in flocks. There is no scientific evidence that routine foot trimming is beneficial in the treatment or prevention of footrot. Wherever possible, sheep producers should maintain a closed flock to prevent purchasing diseased sheep.

CASE 2.45

1 What is the likely cause? The ewe has suffered from gangrenous mastitis caused by either Mannheimia spp. or Staphylococcus aureus. The disease peaks around week 6 of lactation when milk demand is highest. It is most commonly reported in ewes nursing twins, but especially in ewes nursing triplets; it is rarely seen in ewes nursing single lambs.

2 What action would you take? This ewe is unsuitable for future breeding because of welfare concerns and the severe damage to mammary tissue. The infected fibrous/ granulation tissue, and resultant deep inguinal lymph node enlargement, would result in likely carcass condemnation (and raise genuine welfare concerns at the slaughter plant). The fleece is of poor quality because growth has occurred during this period of illness and debility. The ewe should have been euthanased for welfare reasons during the peracute phase of disease because it has suffered for months only to be financially worthless. It is not possible to amputate the proliferative fibrous mass(es) because of the profuse blood supply, and their fibrous nature (2.45b) means that attempting haemastasis by placing sutures does not generate sufficient

pressure to occlude the blood vessels.

3 What control measures could be adopted? Control measures include ensuring ewes are very well fed during early lactation. Farmers should supply appropriate concentrates to ewes and lambs when pasture growth is poor. Farmers must not expect ewes to rear triplets. Identify and treat superficial teat skin lesions with topical antibiotics.

CASE 2.46

1 Describe the sonogram. There are several compartments to this well- encapsulated structure, which extends up to 30 cm. The extensive anechoic area contains a hyperechoic fibrin matrix.

2 What is this structure (most likely first)? The sonographic findings are consistent with a haematoma, probably sited within the broad ligament. The possibility of an inflammatory exudate could be considered, but the lesion is too extensive considering the lack of clinical signs, the fibrin being too extensive and too organised for peritonitis and no involvement of any abdominal viscera.

3 What action would you take? The ewe was euthanased for welfare reasons because of the renal adenocarcinoma. The diagnosis of a large haematoma within the broad ligament (or similar) was confirmed at necropsy (2.46b). It is highly unlikely that this volume of organised blood clot would have been resorbed.

CASE 2.47

1 What conditions would you consider (most likely first)? Ovine pulmonary adenocarcinoma (OPA); chronic suppurative pneumonia; pleuropneumonia/ pleural abscess; mediastinal abscess caused by caseous lymphadenitis (CLA); visna-meadi.

2 How would you confirm the diagnosis? The diagnosis could be confirmed following ultrasonographic examination of the chest. Only about 75% of advanced OPA cases produce copious clear frothy fluid from the nostrils (2.47b; note this sheep is dead) when the ewe's hindquarters are raised (positive wheelbarrow test). However, this ‘test' greatly exacerbates any dyspnoea such that all positive sheep should be killed immediately afterwards for welfare reasons.

3 What treatment would you administer? The prognosis for OPA is hopeless and affected sheep must be culled immediately for welfare reasons and to limit further disease spread within the flock.

4 What control measures could be

attempted in this flock? Control measures include purchase of flock replacements from known OPA-free sources. During winter housing, when the risk of aerosol transmission is greatly increased, group sheep in age cohorts not on keel marks (anticipated lambing date) to limit spread of OPA. When sheep are grouped by age, infection acquired by older sheep from their pen mates does not present such a problem because these ewes would be voluntarily culled at the end of their productive lives before significant lung pathology had time to develop. Isolate suspected cases immediately and cull as soon as the diagnosis has been established. In endemically infected flocks, it has been recommended that sheep with early OPA lesions can be detected after a period of driving, with any exercise-intolerant or dyspnoeic sheep culled at this early stage. There is presently no commercially available serological test for OPA. Where there is a high prevalence of OPA in one group of sheep, cull that group. In closed flocks, cull the progeny of all clinical OPA cases.

CASE 2.48

1 What is the cause of the lameness? It has been proposed that all lameness in neonates is considered septic until proven otherwise. However, in this case there is a greenstick fracture of the right third metacarpal bone.

2 What other conditions would you consider? Differential diagnoses of moderate lameness would include joint trauma and an early joint infection. Foot abscess and interdigital infections can be readily excluded on clinical examination.

3 How would you correct this problem? Apply a plaster or fibreglass cast extending from the foot to the first joint proximal to the fracture site. Typically, fractures of the third metacarpal bone necessitate immobilisation to the carpus. Plaster casts are removed using an oscillating saw after 3 weeks, by which time the fracture site will be stabilised by callus formation. Recasting is not usually necessary but the two halves of the removed cast can be taped together and left supporting the limb for another 2-3 weeks.

Splints can also be used to stabilise distal limb fractures. Typically, plastic foam-lined splints are applied to the front and rear of the distal limb and taped in position. Such splints are popular with shepherds, as they can be quickly applied in the field without a requirement for hot water and there is no time wasted waiting for the cast to harden. Once removed, these splints can be cleaned and reused.

CASE 2.49

1 What is the cause (most likely first)? Cutaneous myiasis; skin wound and secondary nuisance or head fly activity; severe lice infestation. Clinical inspection eliminates other possible diagnoses.

more usual to treat infested sheep with dip wash applied directly to the struck area after first clipping away overlying wool. Antibiotics and a NSAID are indicated in more severely affected individual sheep (2.49b), which must be housed to prevent irritation of the skin wound by head flies.

3 What control measures would you recommend to the farmer? Control of parasitic gastroenteritis relies on targeted anthelmintic treatments, which should be part

2 What treatment options would you consider? The lamb can be treated by plunge dipping using a synthetic pyrethroid or organophosphate preparation, but it is of the veterinary-supervised flock health programme. Where faecal staining of the perineum occurs, this wool must be removed (‘dagging’ or ‘crutching’). Dimpylate (diazinon) and propetamphos are effective against blowfly strike. The synthetic pyrethroids, including high cis cypermethrin, have a much higher human safety margin than the organophosphorus compounds and persist in the fleece for up to 8 weeks.

While topical application of high cis cypermethrin pour-on preparations provides protection against fly strike, these preparations persist for only 6-8 weeks and require reapplication in most situations. Cyromazine applied before the risk period is effective against blowfly strike for up to 10 weeks after topical application. Dicyclanil provides 16 weeks full body protection against cutaneous myiasis. The extended meat withhold times may help decide which product to use

when lambs are close to sale.

CASE 2.50

1 Describe the sonogram. There is severe hydronephrosis with a fluid-distended renal pelvis and reduced renal cortex (2.50b). There is approximately 7-8 cm of fluid separating the kidney from the abdominal wall, which is abnormal. This fluid contains numerous large tags, which are likely to be fibrin strands. There is 1-2 cm of fluid immediately outside the renal capsule (2.50b).

2 What has caused this problem? Urethral obstruction results in bladder distension and this back pressure causes bilateral hydroureter and hydronephrosis. The fluid surrounding the right kidney is likely to be urine; haemorrhage and development of a fibrin clot would cause a much larger hyperechoic area than the strands visible in 2.50a.

3 What action would you take? Such renal pathology is irreversible and the ram should be euthanased for welfare reasons.

Hydronephrosis is avoided by prompt identification of the sick ram by the shepherd, with immediate veterinary attention to relieve the urinary tract obstruction. In most cases the urethral obstruction is caused by a calculus within the vermiform appendage, which is simply excised. Obstruction proximal to the sigmoid flexure in a valuable breeding ram is corrected by tube cystotomy. A sub-ischial urethrostomy can be used as a salvage procedure but should be very carefully considered because ascending infection commonly results in cystitis (and pyelonephritis), with clinical signs detected after approximately 6 weeks.

4 How could this problem have been prevented? Correct ration formulation with appropriate mineral supplementation (low magnesium) is the basis for prevention of urolithiasis in intensively reared sheep. Urine acidifiers, such as ammonium chloride, are commonly added to rations. Sodium chloride can be added to rations to promote water intake. Provision of roughage promotes saliva production and water intake. Fresh clean water must always be available.

CASE 2.51

1 What is the lesion? A keloid or keratoma.

2 What is the likely cause? The cause is keratinisation of a skin injury following repeated damage to the skin overlying the poll caused by fighting injury. The role of contagious pustular dermatitis (orf) virus in the aetiology of a keloid has been suggested but not proven.

3 What action would you take? Such lesions grow very slowly and no action is needed. Surgical removal is rarely possible, or advised, due to the broad base and profuse blood supply. Haemostasis would prove difficult; cautery could be attempted but aggravation of the lesion may lead to granulation tissue. Broken skin lesions on the poll attract head flies and a pour-on fly repellent should be applied before, and throughout, the fly season.

CASE 2.52

1 What is the cause of this problem (most likely cause first)? Feeding around head wounds and ear tag injuries (and horn base) by the muscid fly Hydrotea irritans causes considerable irritation that frequently results in self-trauma. Grazing patterns are disturbed and affected sheep often isolate themselves. They may stand with the head held lowered, with frequent head shaking and ear movements. Alternatively, sheep adopt a submissive posture in sternal recumbency with the neck extended and the head held on the ground. Kicking at the head often greatly exacerbates damage caused by head flies around the horn base, and such action may also traumatise the skin of the neck and ears. Head rubbing also causes considerable self-trauma. Bleeding and serum exudation attracts more flies and aggravates the problem. There is rapid loss of condition in severely affected sheep. Myiasis may result in some cases.

2 How can this problem be controlled? Housing is essential for sheep with large skin lesions to allow time for complete healing. Topical emollients and antibiotic preparations are not usually necessary, and skin wounds heal well provided flies are denied access to these areas. Pour-on fly control preparations, such as high cis cypermethrin or deltamethrin, must be applied before the anticipated head fly season and especially to horned sheep. Such treatments should be repeated every 3-4 weeks during the fly season or as directed by the data sheet instructions. Following an apparently minor lesion, head flies present a serious welfare issue, which should not be underestimated.

CASE 2.53

1 Comment on the quality of the straw and any associated disease risks to pregnant ewes. Bacillus Iicheniformis is associated with poor quality/mouldy straw stored outdoors and is a recognised pathogen causing late abortion in cattle; there are few reports of such abortion in sheep. However, such poor quality straw will be unsuitable for bedding material for sheep and poor underfoot conditions in the sheep shed may predispose to spread of footrot and an increased incidence of infectious diseases in newborn lambs due to poor hygiene and high environmental bacterial load/challenge.

2 Comment on the silage feeding and any associated disease risks. Punctured silage wraps are a risk factor for listeriosis because ingress of air allows rapid multiplication. It has been postulated that listeria contaminated silage results in numerous latent infections in the intestinal wall, often approaching 100% of the exposed flock, but clinical listeriosis in only a few animals. Listeria that are ingested or inhaled tend to cause septicaemia, abortion and latent infection or cause encephalitis via minute wounds in the buccal mucosa, with ascending infection of the trigeminal nerve.

3 How can these disease risks be reduced? Every effort must be taken not to puncture wrapped silage bales during handling and storage, with all punctures sealed immediately. Stores of wrapped silage bales must be fenced against farm stock and vermin. The use of additives at the time of ensiling produces a more acidic pH, which discourages multiplication of L. monocytogenes. Outbreaks of listeriosis occur 10-14 days after feeding poor quality silage. Use of that particular silage should be discontinued whenever possible and any spoiled silage (punctured wraps etc.) should be discarded routinely or fed to growing cattle at the farmer’s risk. Straw should be stored under cover wherever possible.

CASE 2.54

1 What is the most likely cause of this pathology? Pigmented strain of Johne’s disease (paratuberculosis). The grossly thickened and corrugated ileum is typical of Johne’s disease; as a simple guide you can read newsprint (font size 14 and above) through stretched overlain normal intestine but not thickened gut affected by Johne’s disease. A sample of ileum and mesenteric lymph node should be submitted for histopathology and Ziehl-Neelsen staining where doubt exists over the diagnosis. Pigmented strains of Mycobacterium paratuberculosis causing orange discolouration occur in 5-15% of cases.

2 What has this single necropsy revealed? A single necropsy is expensive and gives no indication of disease prevalence.

3 What advice would you offer? Other lean ewes (2.54b) should have blood samples analysed for serum protein concentrations because this is the cheapest and most informative initial screening test to determine the significance of the single necropsy result. Sheep with Johne’s disease have profound hypoalbuminaemia (serum values 30 g/l [3 g/dl]) and normal globulin concentration. These protein concentrations

may very occasionally be encountered in cases of severe chronic parasitism; protein-losing nephropathies are rare. Typically, in chronic fasciolosis and chronic bacterial infections there is hypoalbuminaemia (55 g/l [5.5 g/dl]; normal range 2-3 cm in diameter present at the pleural surface.

3 What treatment would you administer? The ewe was euthanased because of extensive OPA lesions identified during ultrasonographic examination, which were subsequently confirmed at necropsy (2.55b). Note that fibrin deposition is present only over lung affected by OPA, presumably because the tumour compromised the

physical lung defences in these areas. There are also widespread petechiae on the lung surface consistent with septicaemia.

Septicaemia secondary to OPA is not uncommon after a stressful event such as housing. Recent veterinary laboratory data show that more than 50% of acute respiratory disease cases in adult sheep are associated with OPA. Always suspect OPA in cases of acute respiratory disease in adult sheep until proven otherwise,

even though the tumour may have been growing slowly in the lungs for many months. Failure to clear bacteria from the lower airways in OPA compromised lung may explain the association with septicaemia and sudden illness/death.

CASE 2.56

1 What is the cause of this problem? Umbilical infection with Fusiformis necrophorum causing hepatic necrobacillosis and associated local peritonitis/ adhesions.

2 Could this problem have been diagnosed? In some lambs the liver can be palpated extending beyond the costal arch, and digital pressure caudal to the xiphisternum may elicit a painful response. Transabdominal ultrasonography immediately caudal to the costal arch in the ventral midline would identify liver abscesses, but there are no such reports in the literature.

3 What treatment should have been given? Prompt recognition and antibiotic treatment of hepatic necrobacillosis may arrest growth of the infective lesions; thereafter, liver regeneration may restore health, although such lambs are unlikely to grow as well as their healthy co-twin. However, this is largely supposition and the extent to which the liver regenerates in hepatic necrobacillosis remains unknown. The causal organism is fully susceptible to penicillin. If there is associated local peritonitis/adhesions to adjacent small intestine (this case), the animal will not respond to antibiotic therapy because the major problem is impaired movement of digesta through the intestines.

4 Could this problem have been prevented? The umbilicus (navel) must be fully immersed in strong veterinary iodine BP within the first 15 minutes of life and repeated at least 2-4 hours later. Antibiotic aerosol sprays are much inferior to strong veterinary iodine BP for dressing navels, and are much more expensive. This essential routine procedure can be incorporated into the management routine when the ewe and her lambs are penned soon after birth, and again 2-4 hours later when the shepherd checks that the lambs have sucked colostrum.

CASE 2.57

1 What are your thoughts on this subject? There is no reason to castrate a lamb that will reach market weight by 6 months old. After that age, fighting behaviour between male lambs may reduce growth rate and cause individual injury. Castration is now rare in the pig industry and bull beef is standard practice for calves from the dairy industry.

The lamb is more than 1 week old, therefore this means of castration in the UK is illegal, although it is not uncommon to observe this method in lambs older than the legal limit. The lamb shows acute intense pain, frequently lying down with the hindlegs extended, rolling, kicking with its hindlegs and frequent vocalization. There is a large body of evidence that tail docking and castration cause both acute and chronic pain in lambs. An alternative method using a Burdizzo bloodless castrator is unpopular because the method requires two people and the procedure is not 100% effective in many situations because of operator error. Surgical castration again requires two people and risks infection of the open wounds, including tetanus in unvaccinated flocks, and herniation of intestines through the inguinal ring.

Assessment of lamb welfare after castration based on behaviour, serum cortisol and heart rate has sought to evaluate the various methods available. Burdizzo castration followed immediately by local injection into the spermatic cord produced the least pain, but is not considered practical under working conditions on the farm.

Injection of lambs with a NSAID before castration reduces pain but does not completely eliminate it. NSAIDs are being increasingly used to treat a wide range of painful conditions in sheep despite limited data on their clinical efficacy as analgesics. Experimental data are available on the benefits of NSAIDs in treating toxic infections. Although there are no licensed NSAIDs in the UK, they can be administered to sheep under ‘the cascade system’.

CASE 2.58

1 What conditions would you consider? Lesion adjacent to, or involving, the optic chiasma such as a pituitary tumour; basilar empyema; cerebral abscess; closantel toxicity. Diagnosis is based on bilateral involvement of cranial nerves II and III. The obtunded mentation could be explained by a large mass causing high intracranial pressure.

2 What treatment would you administer? There is no treatment for a pituitary tumour, although there may be temporary improvement after dexamethasone injection. There is no reported link to long-term exposure to plant poisons such as bracken.

3 What action would you take? The affected sheep was euthanased for welfare reasons and the diagnosis confirmed at necropsy (2.58b).

CASE 2.59

1 What conditions would you consider? Infectious keratoconjuctivitis (IKC); periorbital eczema.

2 What treatments would you recommend? The two common causal organisms, Mycoplasma conjunctivae and Chlamydia psittaci, are susceptible to a wide range of antibiotics including oxytetracycline. Ewes with severe lesions should be injected IM with long-acting oxytetracycline (20 mg/kg). For cost reasons, topical oxytetracycline ophthalmic ointment or powder is applied daily for up to 3 days in mild cases, although there is marked improvement after only one treatment. Ophthalmic powder adheres to the moist conjunctivae, whereas ointment tends to slip off the cornea, especially when the contents of the tube are cold. There is poor immunity and recurrence of IKC is common.

3 What action would you recommend? Ewes in advanced pregnancy with impaired vision in both eyes should be housed, thereby ensuring adequate feeding to prevent ovine pregnancy toxaemia and deaths from misadventure. Ewes should be taken off exposed hill ground when storms are forecast, but this is not always possible. Occasionally, outbreaks of IKC occur associated with concentrate/roughage feeding; in these instances the space allowance should be increased.

CASE 2.60

1 What conditions would you consider (most likely first)? Include: peritonitis causing ileus arising from an umbilical infection; hepatic necrobacillosis; intussusception; abomasal bloat.

2 What treatment would you administer? The lamb is severely dehydrated, therefore fluid therapy is necessary and would best be administered IV; oral fluid therapy, while much cheaper, may exacerbate the abdominal pain. Antibiotics and NSAID therapy should also be administered.

3 What action should be taken? The severity of the clinical signs is such that the prognosis is guarded and the decision was taken to euthanase the lamb for welfare reasons. The provisional diagnosis of peritonitis associated with umbilical infection was shown to be incorrect, with an intussusception revealed at necropsy (2.60b, arrow).

4 How can this problem be avoided? No obvious cause of the intussusception was found, therefore no advice regarding prevention could be given; no further cases were recognised.

CASE 2.61

1 What is the likely diagnosis? Include: chronic mastitis - occurs sporadically after weaning but lesions are not usually so extensive; exacerbation of udder infection present during previous lactation.

2 Are there any consequences of such conditions? Consequences of udder infection includes bacteraemic spread with secondary lung/pleural abscesses.

3 What pathogens could be involved? Trueperella pyogenes and Staphylococcus aureus are the most common isolates from udder abscesses.

4 What is the prognosis? The udder lesions will not resolve despite antibiotic therapy because of the thick-walled abscesses and extensive fibrous tissue reaction. These ewes are unsuitable for breeding stock. Affected ewes can be sent for slaughter but there is the risk of carcass condemnation because of lymphadenopathy, particularly the deep inguinal lymph nodes, and the possibility of abscesses in the parenchymatous organs following bacteraemic spread.

5 What control measures could have been adopted? Subcutaneous injection of tilmicosin at weaning has proved successful for the control of post-weaning mastitis in ewes, but such treatment is considered by farmers to be too expensive.

CASE 2.62

1 What conditions would you consider (most likely first)? Include: hypocalcaemia; ovine pregnancy toxaemia; acidosis resulting from carbohydrate overfeeding; listeriosis; botulism.

2 How could you confirm your diagnosis? In sheep recumbent due to

hypocalcaemia, serum calcium concentrations are below 1.2 mmol/l (4.8 mg/dl). Serum 3-OH butyrate concentrations can be elevated, especially if the ewe has been inappetent for more than 12 hours. Appearance of ruminal contents at the sheep's nostrils often leads to a misdiagnosis of pneumonia by farmers. the shoulder may take up to 4 hours, especially if the solution has not been warmed to body temperature or injected at only one site.

3 What treatment(s) would you administer? There is a rapid response to slow IV administration of 30 ml of a 40% calcium borogluconate solution, with eructation and defaecation. This ewe was able to regain her feet (2.62b). The response to SC administration of 60-80 ml of 40% calcium borogluconate solution injected over the thoracic wall behind

4 What control measures would you recommend? Hypocalcaemia is not uncommon in 3-crop or older ewes during late gestation, but can also occur sporadically during early lactation. ‘Outbreaks' of hypocalcaemia can result following errors in formulating home-mix rations with incorrect mineral supplementation and inadequate mixing, stress related events such as dog worrying, severe weather, gathering for vaccination, after ewes are moved on to good pastures before lambing and within 24-48 hours of housing.

CASE 2.63

1 What conditions would you consider? The most likely conditions to consider for the skin lesions include: heavy infestation with the chewing louse Bovicola ovis; psoroptic mange (sheep scab); scrapie.

2 How would you establish a specific diagnosis? Large numbers of lice are observed in the fleece, with up to 10-20 lice per fleece parting; very few lice are observed on other sheep in the group. An average count of more than five B. ovis per fleece parting is generally considered a heavy infestation. The slow reproductive capacity of B. ovis results in a gradual build-up of lice numbers over several months. Lice numbers can be very high on sheep in poor condition; they are the result, rather than a cause, of poor condition.

3 What treatment would you recommend? Lice infestations can be controlled with topical application of high cis cypermethrin or deltamethrin. Infested sheep can also be treated by plunge dipping in a synthetic pyrethroid or organophosphate preparation (availability may vary in certain countries). Further investigation revealed that this ewe was suffering from paratuberculosis.

4 What control measures would you recommend? There is no treatment for paratuberculosis and control measures are based on biosecurity/biocontainment and vaccination. Maintenance of a closed flock and effective biosecurity measures will prevent introduction of louse infestation. Annual dipping practices will eliminate this obligatory parasite.

CASE 2.64

Comment on this image (2.64). The term ‘mutilation' (deprive of an essential part) is often chosen to refer to tail docking to provoke reaction by farmers because of the acute and chronic pain resulting from this wholly unnecessary procedure. The tails of these lambs have been docked, which is routinely performed in most sheep flocks, to aid in the control of blowfly strike and to present clean sheep at slaughter plants; however, it has clearly proven unsuccessful in this case. It is a legal requirement that sufficient tail remains after docking to completely cover the sheep's anus and vulva (distal to the caudal skin folds). Tail docking has not prevented faecal contamination of the tail and perineum in this situation, and these lambs remain susceptible to the risk of cutaneous myiasis.

Controlling endoparasite-induced diarrhoea by operating safe grazing systems and/or appropriate use of anthelmintics and pour-on insect growth regulators (e.g. dicyclanil), are much more effective measures to control blowfly strike than tail docking, which is a centuries old practice introduced before effective chemical control measures; review is long overdue. Tail docking has long been banned in horses and, more recently, in dogs by enlightened parliaments. Tail docking is banned in piglets unless there are specific issues of tail biting that cannot be controlled by other means. In the longer term, selection of rams for increased resistance to parasitic gastroenteritis may help to reduce faecal contamination of the perineum and tail.

CASE 2.65

1 Describe the important ultrasound findings. Normal aerated lung tissue present dorsally (left of sonogram) reflects sound waves and the lung surface (visceral pleura) appears as a continuous hyperechoic (bright white) line. The uniform hypoechoic (darker) area ventrally represents cellular proliferation/ infiltration allowing transmission of sound waves. A broad bright line is readily demonstrable where the sound waves transmitted from the probe head pass through the tumour mass then hit aerated lung. This sharply demarcated hypoechoic area is characteristic of the well-defined tumours of ovine pulmonary adenocarcinoma (OPA).

2 How could you confirm the provisional diagnosis? These sonographic findings are pathognomic for OPA. There is no serological test, such as agar gel immunodiffusion test or ELISA, because infected sheep do not make a detectable antibody response to jaagsiekte sheep retrovirus (JSRV). A PCR test has been used in research on OPA for several years. However, while the test is highly sensitive in laboratory assays, it fails to detect JSRV in most infected sheep other than overt clinical cases. This is because there are few infected cells in the blood during the early stages of disease progression. The sensitivity of a single blood test in field samples identifies only 11% of animals with OPA.

Despite the limitations of the existing blood PCR assay for OPA, testing of a number of animals within a flock should indicate whether the virus is present in the flock.

Copious amounts (50-200 ml) of clear frothy fluid pour from the nostrils of most advanced OPA cases when the hind quarters are raised, but this ‘wheel barrow test’ is negative in approximately 25% of cases. Large well-defined tumours are revealed at necropsy, occupying the ventral margins of the apical, cardiac and diaphragmatic lung lobes (2.65b).

CASE 2.66

1 Comment on the hygiene approach to this common scenario. Farmers must wash their hands and then use arm-length disposable gloves during correction of all dystocias in order to reduce the risk of iatrogenic uterine infection. Obstetrical gel is then liberally applied to the hand of the shepherd’s gloved arm; the fingers of the hand are forced together at their tips to form a cone-shape and then gently introduced into the vagina. Careful examination is essential not only for welfare reasons but because the likelihood of infection of the posterior reproductive tract is greatly increased by trauma. Arm-length disposable plastic gloves are cheap and easily carried in pockets, therefore there can be no excuse for non-compliance with such basic hygiene even under extensive flock management systems. Such precautions should also be seen as a minimum standard to limit the risk of potential zoonotic infections such as Chlamydophila abortus, Salmonella serotypes and Q fever.

Attempted delivery by an unskilled shepherd frequently results in oedema, reddening and bruising of vulval labiae within 1-2 hours. Metritis (2.66b) commonly affects ewes after unhygienic manual interference to correct fetal malpresentation/malposture, causing inappetence and reduced milk production with hungry lambs. All ewes should receive an antibiotic injection after an assisted lambing. Penicillin is the antibiotic most commonly used by sheep farmers and should be administered for a minimum of 3 consecutive days.

Caudal analgesia is strongly recommended for all manipulations undertaken by a veterinary surgeon. This involves extradural injection of 2% per cent lidocaine solution (0.5 mg/kg) at the sacrococcygeal site (caudal block). Blockage of the ewe's reflex abdominal contractions greatly assists corrections/manipulations in dystocia cases and has obvious animal welfare benefits. Reliance on strength by the shepherd to repel the fetus risks serious damage to the ewe.

CASE 2.67

1 What conditions would you consider (most likely first)? Include: bacterial meningoencephalitis; septicaemia; focal symmetrical encephalomalacia; sarcocystosis. Unlike calves, cases of meningoencephalitis are typically encountered in 3-4-week-old lambs.

2 How could you confirm your diagnosis? Collect lumbar CSF under local anaesthesia. Collection using a 21 gauge, 15 mm (5/8 in) hypodermic needle (young lamb) reveals a turbid sample caused by a high white cell concentration, and an frothy appearance visible after sample agitation due to the increased protein content. Laboratory analysis reveals a > 100-fold increase in white cell concentration, comprised mainly of neutrophils (neutrophilic pleocytosis), and >five-fold increase in protein concentration (1.5 g/l [150 mg/dl]), consistent with bacterial meningoencephalitis. Culture of lumbar CSF is largely unrewarding and was not undertaken. Inspection of the brain at necropsy rarely yields any gross abnormality because it proves difficult to interpret the significance of congested meningeal vessels.

3 What treatment(s) would you administer? Antibiotic selection could include florfenicol, trimethoprim-sulpha or a fluoroquinolone if the cause was thought to be Escherichia coli (product licence regarding use in sheep may vary between countries). Penicillin or amoxicillin would be chosen if a gram-positive cause was considered likely. Dexamethasone (1.0 mg/kg IV) given on the first day by some clinicians is considered controversial.

4 What is the prognosis for this lamb? The normal treatment response rate for bacterial meningoencephalitis in lambs showing seizure activity is very poor. There was no treatment response and the lamb was euthanased for welfare reasons 24 hours later.

CASE 2.68

1 What conditions would you consider (most likely first)? Include: listeriosis; peripheral vestibular lesion with trauma to the right superficial facial nerve; basillar empyema.

2 What laboratory tests could be undertaken to confirm your provisional diagnosis? Gross inspection of lumbar CSF collected under local anaesthesia using a 19 gauge, 50 mm (2 in) hypodermic needle (100 kg ram) reveals no abnormality with listeriosis. Laboratory examination reveals an elevated protein concentration of 1.4 g/l (140 mg/dl) (normal 3.0 mmol/l are considered to be consistent with pregnancy toxaemia). Plasma glucose and non-esterified fatty acid concentrations are too variable to confirm the presumptive clinical diagnosis.

3 What treatment(s) would you give? Isolate the ewe and offer palatable feedstuffs. Treatments include a concentrated oral electrolyte and dextrose solution or propylene glycol given PO three times daily. Injection with 4 mg dexamethasone promotes appetite and gluconeogenesis (>16 mg after day 135 of pregnancy will induce abortion, which may save the ewe’s life). An elective caesarean operation to remove the fetuses is rarely successful because retained fetal membranes and septic metritis invariably result. Recovery is further hindered by a severe fatty liver (2.69b).

4 What control measures could be adopted? Control measures include ultrasound scanning, which would identify ewes carrying multiple fetuses. Correct nutrition during gestation is essential, especially for multigravid ewes, which are at most risk from energy deficiency due to fetal demands. Routine monitoring of late gestation

nutrition is strongly recommended and the reader is directed to the article by Dr Angus Russel*, which gives accurate guidelines based upon 3-OH butyrate concentration, fetal number and ewe bodyweight. A veterinary advisory visit undertaken 4-6 weeks before the lambing season is the cornerstone of any flock health programme.

* Russel A (1985) Nutrition of the pregnant ewe. In Practice 7:23-28.

CASE 2.70

1 Describe the sonogram. The broad hyperechoic line representing the lung surface (visceral pleura) has been replaced by a 5 cm diameter anechoic area containing multiple hyperechoic dots bordered distally by a broad hyperechoic capsule.

2 What is your diagnosis? The sonographic findings are consistent with a well- encapsulated abscess.

3 What treatment(s) would you administer? Published studies have shown that daily treatment with procaine penicillin for up to 42 days is successful in sheep identified with pleural/superficial lung abscesses measuring 2-8 cm in diameter; more extensive lesions and pyothorax cases have a poorer prognosis. The ram was treated with procaine penicillin IM daily for 4 weeks and made a good recovery. It is possible that there were abscesses in other viscera such as the liver and kidneys as a consequence of bacteraemia, but none were identified. It is not clear why this ram responded to antibiotic therapy when the abscesses appeared to be well-encapsulated; it is possible that other microscopic lesions were not identified.

4 What other imaging modality could have been used? Radiography with the left chest against the plate and the leg drawn forward (2.70b) identifies a lesion immediately cranial to the heart but, unlike with ultrasonography, it is not possible to confirm that this structure is an abscess. Smaller lesions cannot readily be identified on the radiograph.

CASE 2.71

1 What conditions would you consider (most likely first)? Include: molar dentition problems (tooth loss, sharp enamel ridges, overgrowth, etc.); listeriosis.

2 How would you investigate this problem? A mouth gag and torch are essential. Be aware that sheep struggle with the mouth gag in place so the shepherd must secure the sheep in the corner of the pen. An oblique lateral view radiograph of the head (plate positioned next to the left side) reveals that all three lower premolars and the first two molars on the left side are missing (2.71b). There is considerable bone resorption surrounding the lower third molar tooth on both sides.

3 What actions/treatments would you recommend? Loss of cheek teeth due to periodontal disease is a common cause of poor body and condition loss in older sheep. Ewes with poor dentition fatten well when fed a high concentrate diet (up to 1.5 kg/head/day) and this is the best commercial option for the farmer. Care must be exercised to avoid acidosis as the ewes are slowly introduced on to a high concentrate ration.

CASE 2.72

1 What common conditions would you consider (most likely first)? Nematodirosis; coccidiosis.

2 What tests could be undertaken to support your provisional diagnosis? Sudden hatching of overwintered infective third- stage larvae (L3) of Nematodirus battus after a prolonged period of cold weather can cause sudden-onset profuse diarrhoea, leading to death in young lambs. Faecal samples are usually negative for worm eggs (2.72b; large brown N. battus egg in centre [arrow]) in acute nematodirosis because the infection is not yet patent. Necropsy reveals

2 Sheep: Answers

catarrhal enteritis and acute inflammation of the small intestine, with varying numbers of developing larvae and adult worms.

3 What control measures would you recommend? Nematodirosis is a problem where lambs graze pasture used for lambs the previous year. Control by means of safe grazing with alternate years cattle, crops and sheep can rarely be practised on many sheep farms. Prophylactic anthelmintic treatment based on disease risk (weather forecasts) may be necessary to avoid costly disease outbreaks where lambs graze contaminated pastures. Where the timing of prophylactic anthelmintic treatment is in doubt, treat early; such treatment can always be repeated later if considered to be mistimed. Anthelmintic resistance is not a concern with Nematodirus battus and Group 1 anthelminitics (benzimadazole anthelmintics), which are otherwise largely ineffective due to resistance in most other nematode species, are commonly administered. Isolated incidents of resistance to benzimadazole anthelmintics have been reported in N. battus but this is not a major concern at present.

CASE 2.73

1 What conditions would you consider (most likely first)? Include: contagious pustular dermatitis (CPD, orf, scabby mouth, contagious ecthyma); dermatophilosis; bluetongue; sheep pox (not UK).

2 What treatment would you administer? Intramuscular injection of procaine penicillin for 3-5 consecutive days and topical antibiotic spray can be used to control superficial secondary bacterial infection, but this is not necessary in this situation.

3 What samples would you collect to confirm your diagnosis? CPD virus can be demonstrated by direct electron microscopy of fresh lesions. Bacteriology of the skin lesions to investigate the role of secondary bacteria is of doubtful benefit.

4 What preventive measures could be considered for next year? Orf vaccine must never be used in a clean flock. Vaccination is by scarification of the inner thigh in lambs and the axillary region in ewes. The timing of vaccination is approximately 6 weeks before the anticipated occurrence of disease. Care must be exercised during handling of the live vaccine as it is affected by high temperatures and inactivated by disinfectants. Control thistles, gorse, etc. wherever possible. Orf is a zoonosis, therefore extra care is necessary when handling infected sheep and during vaccination.

CASE 2.74

1 What is the likely cause (most likely first)? Microphthalmia, an autosomal recessive condition recognised in certain breeds, such as the Texel, which can occur at a high prevalence following the introduction of a new ram.

2 What action would you take? Affected lambs should be euthanased for welfare

reasons.

3 What advice would you offer? The carrier ram should be identified and culled.

CASE 2.75

1 What conditions would you consider? Include: nephrosis; chronic infection such as suppurative pneumonia; starvation/rejection by dam; coccidiosis.

2 How would you confirm your diagnosis? Laboratory analysis reveals a markedly elevated blood urea nitrogen concentration (54.2 mmol/l [151.8 mg/dl]; normal 2-6 mmol/l [5.6-16.8 mg/dl]) and a low serum albumin concentration (20 g/l [2 g/dl]; normal >30 g/l [3 g/dl]) consistent with a diagnosis of nephrosis. The serum globulin concentration is normal (43 g/l 4.3 g/dl]; normal 35-50 g/l [3.5-5.0 g/dl]), ruling out chronic bacterial infection. Faecal examination for oocysts and strongyle eggs proves negative.

3 What is the prognosis for this lamb? The prognosis is hopeless and the lamb should be euthanased for welfare reasons. Necropsy reveals enlarged pale kidneys typical of nephrosis (2.75b). This provisional diagnosis was confirmed on histological examination of stained sections.

4 What control measures would you

recommend? There are no specific control measures for nephrosis. For future years the farmer was advised to consider adding decoquinate to the lamb creep to control coccidiosis.

CASE 2.76

1 Describe the important necropsy findings shown. There are widespread petechiae over the myocardium. The lungs appear congested and very oedematous.

2 What is the most likely cause? Mannheimia haemolytica, which causes septicaemia in young lambs.

3 How could you confirm your suspicion? Diagnosis is based on bacteriology from various viscera including lung, liver, kidney, spleen, thoracic fluid and heart blood. Histopathology of lung tissue is also advisable.

4 What control measures could be adopted? Vaccination of the dam with a pasteurella vaccine will only provide passively-derived immunity for the first 4 weeks or so of life. Thereafter, vaccination of lambs from 3 weeks old is needed to provide active immunity. Two vaccinations are required 4-6 weeks apart then annual vaccination 6 weeks pre-lambing. This vaccination protocol may not have prevented disease in this lamb, but is the best available option.

CASE 2.77

1 What is your diagnosis (most likely first)? The most likely conditions to consider include: Streptococcus dysgalactiae polyarthritis; polyarthritis caused by another bacterium such as Escherichia coli.

2 How would you confirm your diagnosis? Arthrocentesis often fails to yield sufficient exudate for analysis or bacteriology because chronic joint infection is composed of a pannus (2.77b). The lamb will not recover and should be euthanased for welfare reasons. A sample of synovial membrane collected at necropsy yields a higher bacteriology success rate than a joint aspirate. Where possible, samples should be collected from lambs that have not received antibiotic therapy. Radiography would not yield conclusive evidence of joint infection.

3 What treatments would you administer? Recent studies have shown that S. dysgalactiae is resistant to

oxytetracycline. Procaine penicillin remains the drug of choice for all streptococcal infections in farm animals. A minimum of 5-7 consecutive days of IM procaine penicillin should be administered because this drug is time-dependent. Long-acting penicillin preparations are not appropriate and should not be used as a convenient alternative. As with cases of atlanto-occipital joint infection caused by the same bacterium, there is a rapid and dramatic response to dexamethasone administered on the first day of antibiotic therapy. This response is much better than a NSAID. (Note: S. dysgalactiae causes >90% of joint infections in lambs, therefore the corticosteroid injection is given at the same time as an effective antibiotic.)

4 What preventive measures could be adopted? The shepherd had immersed the lambs' navels in strong veterinary iodine on three occasions within the first 6 hours of life. Hygiene measures in the lambing shed and ensuring passive antibody transfer often fail to reduce ongoing problems of S. dysgalactiae polyarthritis. Changing the lambing accommodation is rarely possible other than turning housed ewe out to pasture, but this increases the risks from hypothermia and causes problems catching ewes with dystocia problems. In an emergency situation of high disease prevalence, prophylactic penicillin injection of lambs around 24 hours old is often effective but unsustainable.

CASE 2.78

1 How will you deal with this case? Vaginal prolapse is a common condition of late gestation but it is concerning that this sheep is recumbent and unresponsive on approach. The major complications associated with vaginal prolapse could include: rupture of a middle uterine artery and extensive haemorrhage; hypocalcaemia; fetal death/autolysis/resultant toxaemia.

Examination of the conjunctivae reveals very pale mucous membranes (2.78b) indicating severe anaemia/ haemorrhage.

2 What is the future management

of this sheep? The ewe should be euthanased immediately for welfare reasons. Greater patience should be exercised when sheep with prolapses are gathered from the field with dogs, as it is assumed that the uterine artery ruptures when the sheep is running away from the dogs/farmer's quad bike.

CASE 2.79

1 What conditions would you consider? The most likely conditions to consider would include: polioencephalomalacia (PEM; syn. cerebrocortical necrosis, CCN); focal symmetrical encephalomalacia; meningitis/brain abscess; sarcocystosis; listerial meningitis.

2 What treatment would you administer? Treatment for PEM includes injection of thiamine (10 mg/kg IV twice daily on the first occasion, then IM twice daily for 2 more days). There is evidence from field studies that IV injection of dexamethasone (1 mg/kg), or a similar short-acting corticosteroid, aids recovery by reducing brain swelling.

3 What is the prognosis for this case? The prognosis is good when sheep are presented early in the clinical course; this sheep made a rapid recovery.

4 How can the diagnosis be confirmed? Diagnosis is confirmed by the rapid response to timely thiamine treatment. Diagnostic biochemical parameters for on the histological findings in the cortical lesions of vacuolation and cavitation of the ground substance, with astrocytic swelling, neuronal shrinkage and necrosis.

PEM include thiaminase activities in blood; rumen fluid or faeces are rarely used in farm animal practice. At necropsy affected areas of the cerebral cortex may exhibit a bright white autofluoresence when cut sections are viewed under ultraviolet light (Wood's lamp; 365 nm) (2.79b). This property has been attributed to the accumulation of lipofuchsin in macrophages, but not all PEM cases fluoresce. Definitive diagnosis relies

5 What control measures would you recommend? Disease occurs sporadically and there are no specific control measures. Prompt recognition and veterinary treatment are essential for a full recovery.

CASE 2.80

1 What conditions would you consider (most likely first)? Small intestinal torsion around the root of the mesentery; bloat (choke is rare in sheep); ileus caused by grain overload; except for uterine perforation/infection, peritonitis is uncommon in sheep.

2 What further investigations would you undertake? Transabdominal ultrasound examination takes only 2 minutes. Typically, with abdominal catastrophes, there is much reduced gut motility with marked distension of intestinal loops and perhaps an increased amount of fluid/exudate within the peritoneal cavity.

3 What treatment would you administer? A very high heart rate and toxic mucous membranes afford a grave prognosis. Symptomatic treatment could include ‘shock dose' IV fluid therapy. NSAID therapy should also be administered to control pain and likely endotoxaemia. However, these treatments will not correct the primary problem of suspected intestinal torsion and the ewe should be euthanased for welfare reasons. The torsion was confirmed at necropsy (2.80b).

4 How can this problem be avoided? Small intestinal torsion around the root of the mesentery is uncommon in adult sheep, but recent exposure to lush pasture and concentrate feeding may have played a role. The farmer reported having never encountered any similar cases over the past 5 years and was unwilling to change his flock management, which was aimed at achieving high lamb growth rates ahead of breeding sales.

CASE 2.81

1 What is the cause of this problem? Ulcerative posthitis; wool or other material adherent to the glans; trauma; obstructive urolithiasis.

The vermiform appendage could not be identified because of the dried blood and foreign material adherent to the glans. Surprisingly, the ram was able to urinate normally. Attempts to gently soak the penis in warm water and remove dried blood from the glans resulted only in profuse haemorrhage, with the foreign material remaining firmly adherent. It was not possible to decide whether the superficial bacterial infection on the prolapsed penis was the cause of the paraphimosis or a consequence. While the preputial ring was oedematous, there was no evidence of ulcerative posthitis (sheath rot). This condition is caused by Corynebacterium renale, which contains the enzyme urease capable of breaking down urea in the urine to release ammonia, which is caustic to the epithelium of the prepuce.

2 What action would you take? It was not possible to replace the penis within the sheath. Strapping the penis in a sling close to the ventral abdominal wall to restrict the dependent oedema was thought to likely cause more trauma when the ram lay down.

3 What treatment would you administer? Daily IM penicillin therapy was started on the assumption that Corynebacterium renale was a likely secondary bacterial invader. A single injection of dexamethasone was administered on day 1 to reduce oedema. The prolapsed tissues were bathed in very dilute povidone-iodine solution followed by topical corticosteroid and antibiotic cream applied four times daily.

4 What is the prognosis? The prolapsed tissue remained largely unchanged after

5 days treatment, so the treatment was continued. By day 8 the ram was able to withdraw most of his penis into the sheath, and completely by day 10. There was no obvious reason for the sudden improvement, as the treatment had not changed.

CASE 2.82

1 What is the reasoning behind this management decision? Poor or reduced grazing is thought by farmers to speed up the ‘drying off' process and reduce the incidence of mastitis, but there is little evidence that this management practice works.

2 What are the alternative management strategies? There are no licensed long- acting intramammary antibiotic preparations for sheep in many countries, although preparations for cattle are used ‘off-label’ at weaning to eliminate/ reduce chronic infections and prevent establishment of new infections in the udder during the dry period. Care must be exercised with intramammary infusion in sheep because iatrogenic infections are common when the procedure is undertaken in wet or unhygienic conditions. Appropriate teat disinfection before antibiotic infusion is essential. The intramammary syringe nozzle is held against the teat orifice; it must not be forced into the streak canal.

Encouraging results have been reported for the treatment of mild cases of mastitis that have been acquired during that lactation using tilmicosin at weaning, but the low prevalence and high cost of whole group therapy mean that only pedigree flocks use this protocol. Treatment based on individual ewe monthly milk somatic cell counts could be undertaken in milking ewes, as practised in dairy cattle.

Treatment of chronic mastitis that has progressed to abscessation within the gland is not usually undertaken because of the hopeless prognosis and associated loss of normal mammary tissue and lactogenesis. Ewes with chronic mastitis and abscesses (2.82b) should be culled following identification at weaning or at the pre-breeding check.

CASE 2.83

1 What advice would you give? Testing for triple resistance (Groups 1-3) could be undertaken using a faecal egg count reduction test (FECRT), but your client considers this too much work and expense. Furthermore, the lambs were purchased from multiple sources. The FECRT uses approximately 10 sheep randomly allocated to control and treatment groups (one for each class of anthelmintic to be tested). A faecal worm egg count is then undertaken for all sheep and repeated 10 days later for 2-LV group sheep and 14 days later for control sheep, 1-BZ and 3-ML groups. Anthelmintic resistance is suspected where the mean faecal worm egg count is less than 95% of the percentage reduction in the control group.

Quarantine arrangements are considered essential to reduce the risk of introducing anthelmintic-resistant worms of species such as Haemonchus contortus and Teladorsagia circumcincta. Current best practice involves sequential full-dose treatments with either 4-AD monepantel (Zolvix®) or 5-SI derquantel and abamectin (Startec®), and moxidectin. All introduced sheep should be grazed separately from the main flock for at least 1 month. As no resistance has been reported to date to Groups 4 and 5 in the UK, including moxidectin for store lambs seems excessive and could be omitted.

Whether 10% of the strongest lambs should be left untreated to carry some anthelmintic-susceptible worms over onto the new pasture to reduce selection for anthelmintic-resistant worms is debatable, because all lambs will be slaughtered within 3-4 months, and the field will be used for silage next season.

Lambs may not need to be treated again with an anthelmintic for up to 8-10 weeks; however, this will depend on the amount of infection carried over, the stocking rate and weather conditions (large numbers of lambs left untreated, high stocking rates and wet weather increase challenge). Monitoring of pooled faecal worm egg counts every 7-10 days after 4-6 weeks with fresh faeces collected from around 10 lambs after gathering into a corner of the field can help to decide whether anthelmintic treatment is necessary. Flukicide treatment would be based on where the lambs were sourced and whether a high risk year was predicted following a wet summer. Treatment against very early stage immature flukes would necessitate the use of triclabendazole. It would be advisable to regularly weigh lambs to ensure target growth rates are being met.

CASE 2.84

1 What are these lesions? Paramphistome infections reside in the ventral walls of the rumen and are now considered common in sheep in the UK. Calicophoron daubneyi affects cattle and sheep and was probably introduced into the UK with cattle imported from Europe. C. daubneyi has a similar two-host life cycle to Fasciola heptica but uses a different intermediate snail host.

2 Are these lesions important? Adult flukes are not thought to cause clinical signs, although large numbers of migrating immature rumen flukes may cause transient diarrhoea. Mature rumen flukes are readily identified at necropsy (2.84). Eggs of C. daubneyi can be detected by the same sedimentation technique as F. heptica.

3 What action would you recommend? Treatment is not considered necessary because rumen flukes are thought to cause little clinical disease.

CASE 2.85

1 What conditions can cause sudden death in growing lambs (most likely first)? Mannheimia haemolytica infection, which causes septicaemia in young lambs; Bibersteinia trehalosi infection, which causes septicaemia in 4-9-month-old lambs (systemic pasteurellosis); lamb dysentery and pulpy kidney in lambs that have not received sufficient passive antibody.

2 How could you confirm your suspicion? Diagnosis is based on postmortem findings and bacteriology from lung, liver, kidney, spleen, thoracic fluid and heart

blood. In peracute cases there are widespread petechiae over the myocardium, spleen, liver and kidney, with enlarged lymph nodes and congested and oedematous lungs. Less acute cases often show a considerable fibrinous pleurisy at necropsy. It may prove difficult to differentiate autolytic change from true lung pathology; diseased lung sinks, while normal aerated lung floats (2.85b). There is excess fluid in the body cavities and pericardium, often containing fibrin clots, in sheep that have died from clostridial disease such as pulpy kidney.

3 What control measures could be adopted? Vaccination of the dam with a pasteurella vaccine will only provide passively derived

immunity for the first 4 weeks or so of life. Thereafter, vaccination of lambs from

3 weeks old is needed to provide active immunity. Two vaccinations are required 4-6 weeks apart and at least 2 weeks before any stressful event such as weaning or sale. Vaccinated lambs often obtain a premium at breeding sales.

CASE 2.86

1 What are these ribbon-like segments? Tapeworm segments of the genus Monezia are readily recognised in faeces of young lambs as white ribbon-like structures up to 10 mm wide.

2 What action is necessary? Treatment is not considered necessary because tapeworms are non-pathogenic. Only members of the benzimadazole group (1-BZ) are effective against adult tapeworms.

3 What control measures would you recommend? No control measures are necessary for tapeworms of the genus Monezia.

CASE 2.87

1 What advice would you give? Anthelmintic treatment of all breeding females pre-tupping is rarely necessary. The ewes look to be in very good body condition and there is no faecal staining of the perineum visible to suggest a history of

2.87b

i U

parasitic gastroenteritis. Dosing all ewes pre-tupping may select for anthelmintic resistant strains, especially if ewes are moved immediately to safe grazing for flushing. Faecal egg counts will indicate whether ewe anthelmintic treatment is necessary. In general terms, anthelmintic treatment should be targeted at leaner ewes, sheep pregnant for the first time or those sheep with faecal staining of the perineum. Indeed, it may be a sound selection policy to sell lean ewes and not breed from them, as these sheep are likely to have smaller litters in the next breeding season. Note the difference in body condition of the two ewes shown in 2.87b. The ewe on the right is in much poorer body condition and has faecal staining of the perineum. The farmer elected to keep this sheep, which lost further body condition, subsequently shown to be caused by Johne's disease.

It is not unusual for sheep with paratuberculosis to have high worm eggs counts and diarrhoea due to immune system suppression.

Rams are often neglected at this time and a faecal worm egg count will decide whether pre-tupping anthelmintic treatment is necessary in this group.

Flukicide treatment may be necessary with risk based on weather data throughout the summer and autumn, as described more than 50 years ago by Ollerenshaw (the Ollerenshaw Index). While there are a lot of flukicide/anthelmintic combination

products on the market, these are rarely needed and a flukicide product only should be used.

CASE 2.88

1 Describe the sonogram. The irregular structure is 10 cm in diameter and appears well-encapsulated. There are irregular pockets of fluid at the periphery and beneath the capsule.

2 What is this structure (most likely first)? The sonographic findings are not consistent with any normal viscus. The structure could be: neoplasia involving the kidney; neoplasia involving the uterus; neoplasia involving the bladder.

2 Sheep: Answers

3 What action would you take? While it would be possible to obtain an ultrasound- guided fine needle aspirate of the structure, the prognosis is hopeless and the ewe should be euthanased for welfare reason. Serum BUN, creatinine and proteins would give an accurate assessment of renal function, but are not necessary. A renal carcinoma was confirmed at necropsy (2.88b).

CASE 2.89

1 What common conditions would you consider (most likely first)? Parasitic gastroenteritis; lush grass; chronic fasciolosis.

2 What tests could be undertaken to support your provisional diagnosis? Clinical examination reveals no abnormality and there is no anaemia suggestive of haemonchosis. Faecal samples are taken from six rams, revealing an average worm egg count of 1,800 epg (range 800-2,400) using the McMaster technique; there are a few coccidian oocysts visible on the slide. Sedimentation is negative for liver fluke eggs.

3 What control measures would you recommend? The farmer is aware of the risk of anthelmintic resistance and treats his ewes only once a year with an anthelmintic before lambing time to reduce the periparturient rise. His lambs are treated with an anthelminitc only when they fail to reach target growth rates (targeted selective treatment) and then weaned onto safe grazing to avoid the peak of the mid-summer rise of infective larvae on contaminated pasture. The farmer assumed that rams, like ewes, would be largely immune to parasite challenge except under periods of prolonged stress. Unfortunately, rams remain susceptible to parasitic gastroenteritis throughout their lives and regular faecal egg count monitoring is important, with treatment as necessary to maintain body condition. As the rams are rarely drenched at present, triple resistance would seem unlikely, but it would be prudent to undertake a faecal worm egg count reduction test. As this pasture is likely to be highly contaminated with infective larvae for the remainder of the summer and into autumn, movement to safe pasture where available would be advisable. Where possible, the pasture should be grazed by cattle for the remainder of the year.

CASE 2.90

1 Are there any risks to these young lambs? Yes, sarcocystosis and coenurosis.

Sarcocystis species are obligate two-host parasites. The two potentially pathogenic microcyst species in sheep (S. arieticanis and S. tenella) have either a sheep-dog or a sheep-fox cycle. Coenurus cerebralis is the larval stage of the tapeworm Taenia multiceps, which infests the small intestine of carnivores.

2 What clinical signs would be expected? All ages of sheep may be affected, but neurological signs of spinal cord disease are more commonly observed in 6-12-month-old lambs. The prevalence of neurological disease caused by Sarcocystis spp. in the UK is probably underdiagnosed because the clinical signs are easily mistaken for vertebral empyema. Affected sheep remain bright and alert with a normal appetite. Hindleg paresis has been described with affected sheep adopting a dog-sitting posture (2.90b). Some sheep

recover with supportive care. Seizure activity followed quickly by death has been reported attributed to massive challenge.

Acute coenurosis has been reported in 6-8-week-old lambs where clinical signs ranged from pyrexia, listlessness and head aversion to convulsions and death within 4-5 days. Chronic coenurosis presents as a slowly progressive focal lesion of the brain, typically involving one cerebral hemisphere in 80% of cases, the cerebellum in approximately 10% and affecting multiple locations in 8%. Compulsive circling behaviour is commonly observed in sheep with coenurosis. The presence of a cyst in one cerebral hemisphere causes blindness/loss of the menace response in the contralateral eye.

3 What signs may be noted in these lambs at slaughter? Macroscopic Sarcocystis spp. lesions are commonly observed at slaughter plants in the oesophagus, diaphragm and heart muscle. Cysticercus tenuicollis cysts, the intermediate stage of Taenia hydatigena, may be observed adherent to the omentum and indicate poor parasite control (tapeworms) in dogs accessing the sheep’s grazing.

4 What simple hygiene measures would you recommend? The dogs should be kennelled in a separate building away from other animals. Control is based on preventing completion of the sheep-dog life cycle, including prevention of faecal contamination of pasture and bedding material by dogs, especially litters of puppies, correct disposal of sheep carcasses (a legal requirement in some countries) and not feeding uncooked sheep meat or offal to dogs. The hay should be provided in racks off the ground and replenished daily. Dogs should be regularly treated with an anthelmintic effective against tapeworms.

CASE 2.91

1 What is the lesion (most likely first)? A well-encapsulated 4 cm diameter lesion with a heterogeneous ‘snowstorm’ appearance with a distinct capsule

can be seen. This sonographic appearance is consistent with an abscess. A tumour within the omentum would likely appear more heterogeneous. It is unlikely that there would be four tumour masses of similar size.

2 What is the significance of these lesions? Adhesions between the abscess capsule and small intestine will likely slow the rate of propulsion of digesta through the gut and be responsible for the weight loss; however, the abscesses are largely enveloped by omentum.

3 What action would you recommend? The ewe was euthanased for welfare reasons. Necropsy confirmed the lesions to be abscesses with associated chronic fibrous peritonitis (2.91b).

CASE 2.92

1 What conditions would you consider (most likely first)? Bibersteinia trehalosi infection, which causes septicaemia in 4-9-month-old lambs (systemic pasteurellosis); pulpy kidney in lambs that have not received sufficient passive antibody.

2 What treatment would you administer? Unlike cattle, most pasteurellae causing respiratory disease in sheep are sensitive to oxytetracycline, which should be given IV. A NSAID or dexamethasone should also be given IV to counter the toxaemia; there are no comparative field studies. Confirmation of the diagnosis is based on postmortem findings and bacteriology from lung, liver, kidney, spleen, thoracic

fluid and heart blood. In peracute cases there are widespread petechiae over the myocardium, spleen, liver and kidney, with enlarged lymph nodes and congested and oedematous lungs (2.92b). It may prove difficult to differentiate autolytic change from true lung pathology; a simple test is that diseased lung sinks while normal aerated lung floats. Histopathology of lung tissue should be undertaken wherever cost allows. There is excess fluid in the body cavities and pericardium, often containing fibrin clots, in sheep that have died from clostridial disease such as pulpy kidney.

3 What control measures could be adopted? Vaccination of the dam with a pasteurella vaccine will only provide passively derived immunity for the first

4 weeks or so of life. Thereafter, vaccination of lambs from 3 weeks old is needed to provide active immunity. Two vaccinations are required 4-6 weeks apart and must be completed ahead of the major risk of weaning, often accompanied by change of diet and sometimes sale through a market and long journey times. Metaphylactic injection with either oxytetracycline or tilmicosin could be considered after several more cases, but mortality rarely exceeds 2%, which means there is no financial benefit to the farmer. Lush pasture is considered a risk factor for pasteurellosis and clostridial disease in unvaccinated lambs, but is essential to achieve good lamb growth rates.

CASE 2.93

1 What is the cause of this problem? Umbilical/urachal infection with associated omental and bladder adhesions. Umbilical infection usually tracks to the liver (hepatic necrobacillosis) but can occasionally involve the urachus (2.93b)

2 Where would you extend your necropsy examination? Urachal infection can ascend via the bladder to the kidney but this is unusual in lambs. Propulsion of digesta can be significantly impaired if strong adhesions form to the intestines, but in this case the adhesions involve only the omentum (2.93a). Rupture of the infected urachal remnant causing uroperitoneum has occasionally been reported in calves but not been recorded in sheep.

3 Could this problem have been prevented? Urachal infection can be prevented by fully immersing the umbilical remnant in strong veterinary iodine BP within the first 15 minutes of life and repeating at least 2-4 hours later. Antibiotic aerosol sprays are much inferior to strong veterinary iodine BP for dressing navels, and are much more expensive. This essential procedure can be incorporated into the management routine when the ewe and her lambs are penned soon after birth, and again 2-4 hours later when the shepherd checks that the lambs have sucked colostrum.

CASE 2.94

1 What conditions would you consider (most likely first)? Include: brachial plexus avulsion (possibly caused by the keel harness); radial nerve paralysis following trauma in the mid/distal humeral region; trauma of the shoulder/elbow joints; severe foot lesion (foot abscess, septic pedal arthritis); exacerbation of an elbow arthritis lesion.

2 What treatment(s) would you administer? Clinical examination failed to reveal any evidence of a fracture and there are no joint swellings. The injury occurred 1 week ago, therefore a corticosteroid injection to reduce any associated soft tissue swelling would be unlikely to have much beneficial effect. The ram was isolated indoors to aid recovery and help restore body condition.

3 What is the prognosis for this ram? The ram showed no signs of improvement after 3 months and was culled for welfare reasons. It can prove difficult to differentiate between radial nerve paralysis and brachial plexus avulsion, the latter having a much poorer prognosis.

CASE 2.95

1 What has happened to this sheep? Ear loss following severe oedema and skin necrosis associated with photosensitisation; septicaemia and ischaemic necrosis.

In sheep, photosensitisation occurs either as a primary condition or secondary to hepatotoxic damage resulting in retention of the photosensitising agent phylloerythrin. Primary photosensitisation follows ingestion of photodynamic agents, for example hypericin from St. John’s Wort (Hypericum perforatum). In Norway, ingestion of bog asphodel (Narthecium ossifragum) is reported to cause photosensitisation in large numbers of lambs. In New Zealand, facial eczema is caused by ingestion of the toxin sporidesmin, which is produced by the saprophytic fungus Pithomyces chartarum, which proliferates in vegetation during the autumn months. Sporidesmin is absorbed and accumulates in the liver and bile, where metabolic changes result in the release of free radicals, with consequent damage to the biliary tree and reduced excretion of phylloerythrin.

2 Could anything have been done to prevent this situation? Typical cases of primary photosensitisation occur sporadically in white-faced breeds. Initially, affected animals are dull and attempt to seek shade. The ears in particular are affected and become swollen, oedematous and droopy (2.95b). The response to protection from sunlight and corticosteroid therapy to reduce oedema at this stage is generally good, although some cases do slough the ears. The prevalence of primary photosensitisation in a particular group of sheep rarely exceeds 2% and the source/cause is often not determined.

3 Should this sheep be kept for future breeding? This case was considered to be one of primary photosensitisation and the current excellent body condition of the sheep would indicate that any significant liver pathology (secondary photosensitisation) would be unlikely. There is no reason to cull this sheep.

CASE 2.96

1 Comment on the radiographs. The dorsoplantar view of the right stifle joint shows extensive loss of the articular surfaces. The lateral view shows complete loss of articular surfaces and extensive osteophytosis.

2 Comment on the animal welfare implications of these findings. This sheep would have been severely lame for at least 6-9 months and presents as a serious welfare concern.

3 What are the expected necropsy findings? At necropsy, the right stifle joint shows extensive erosion of articular cartilage with exposure of subchondral bone; the normal left stifle joint is shown for comparison (2.96c). There is synovial membrane hypertrophy, giving the incised affected joint a red colour compared with the white colour of the normal joint.

4 What advice should be given to the farmer? Every lame sheep that does not return to normal within 5-7 days of treatment should be examined by a veterinary surgeon; there is no excuse whatsoever that this ewe has suffered such severe lameness for such an extended period.

CASE 2.97

1 What advice would you offer regarding flock biosecurity? All introduced sheep, especially rams from pedigree breeders, should be assumed to be potential sources of resistant strains of helminth parasites and be treated with an effective anthelmintic or combination of products on arrival on the farm. Quarantine arrangements are essential to reduce the risk of introducing anthelmintic-resistant strains of Haemonchus contortus and Teladorsagia circumcincta. These rams should then be yarded for 48 hours to ensure that any viable nematode parasite eggs have been voided before they are turned onto pasture. After quarantine treatment, the rams should be turned out onto pasture that has been grazed by sheep this season so that any parasites left after treatment make up a very small percentage of an otherwise (assumed) susceptible population ‘in refugia'.

The current recommendation is to use a combination of anthelmintic drugs with different mechanisms of action. Current best practice involves sequential full­dose treatments with either 4-AD monepantel (Zolvix®) or 5-SI derquantel and abamectin (Startec®), and moxidectin.

Quarantine treatment with a flukicide is based on risk analysis and the choice will depend on the likely stage of migrating/adult flukes. Tricalbendazole is the only product effective against early migrating stages of liver fluke. However, it would be prudent to use closantel 6-8 weeks after the use of triclabendazole because of the suspected widespread occurrence of resistance to this flukicide.

All introduced sheep should be grazed separately on contaminated pasture from the main flock for at least 1 month. This quarantine period allows inspection for a range of other common diseases and infections that can be introduced onto the farm but are not visible at sale, such as sheep scab, lice and footrot. Most pedigree sheep flocks are monitored for visna-maedi virus and caseous lymphadenitis, although these diseases are not of major significance for commercial sheep farmers. In flocks where only rams are purchased, veterinary ultrasound scanning of purchased rams to detect early lung lesions of ovine pulmonary adenocarcinoma, with immediate culling before significant virus shedding, is a major step in tackling this disease.

CASE 2.98

1 What is the likely cause (most likely first)? Interdigital dermatitis (scald). Interdigital dermatitis is an acute necrotising infection of the interdigital skin caused by Dichelobacter nodosus and predisposed by wet conditions and trauma to the interdigital skin. It is most commonly seen affecting intensively managed and densely stocked lambs, causing considerable lameness. Footrot is the term commonly used to describe the highly contagious foot disease with extensive underrunning of hoof horn also caused by D. nodosus.

2 What treatment would you administer? If possible, the flock should be moved to dry pasture where spontaneous recovery may occur, but this is not an option in most situations. In the UK, the method of choice is to turn over every lamb and treat all affected feet with topical oxytetracycline aerosol, but this is very labour intensive. Surprisingly, despite the severe lameness there is return to full soundness within 1-2 days of a single treatment.

The use of 5% formalin footbaths produces acceptable results but young lambs do not go through a footbath easily. Farmers sometimes add straw to the formalin solution to encourage sheep to enter the footbath (2.98b), but this practice will

largely negate the bacteriocidal action of the formalin. Footbaths should be cleaned out and replenished before use. The caustic nature of formalin on eroded skin means that lameness is often worse for several days after formalin foot bathing before improving. Zinc sulphate, as a 10% L______________ ..

solution with sodium

lauryl sulphate added as a wetting agent, has largely replaced formalin footbaths.

3 What control measures would you include in the flock health plan? Some farmers report that where there are fewer ewes with footrot, epidemics of interdigital dermatitis in lambs occur less frequently. Regular foot bathing is successful in preventing footrot and reducing the spread of footrot and will also treat interdigital dermatitis. There is no evidence that any one type of footbath formulation is more effective than another. The lack of adequate foot bathing facilities within ready access to grazing means that footbaths are used much less often than is optimal for foot health.

CASE 2.99

1 Do you agree with the decision to undertake a caesarean operation? The cervix and vagina appear thickened and oedematous such that successful digital dilation of the cervix after replacing the cervicovaginal prolapse under low extradural block would be high unlikely. Any delay is likely to compromise viability of the lambs (if they are still alive). Cost is a factor in many situations; is the cost of surgery likely to be greater than the financial value of the ewe and her lamb(s)? Published studies show that successful surgical outcome is >98% when the lambs are alive. The prognosis is very poor if there is a foetid discharge, and euthanasia is perhaps the best option as peritonitis is common due to leakage of uterine content into the peritoneal cavity during surgery. Furthermore, toxins can leak across compromised uterine wall, causing peritonitis.

2 What anaesthetic protocol would you adopt? Excellent analgesia of the flank for caesarean operation can be achieved after lumbosacral extradural injection of 3-4 mg/kg of 2% lidocaine solution and is indicated during first-stage labour associated with a vaginal prolapse. The prolapsed tissues can be readily replaced even

when the ewe is in lateral recumbency (2.99b) and there is complete analgesia of the flank for surgery. The only disadvantage is paralysis of the ewe's hindlegs for 2-3 hours, therefore care of the newly delivered lambs is paramount including ensuring passive antibody transfer. It is not essential to place a Buhner suture afterwards but it may be prudent to do so; this was not undertaken in this case and prolapse did not recur.

CASE 2.100

1 What conditions would you consider? The most likely conditions to consider include: septic pedal arthritis; white line abscess extending to the coronary band; interdigital infection/cellulitis.

2 How would you confirm your diagnosis? The combination of widening of the interdigital space and swelling above the coronary band on the abaxial aspect of the hoof wall is consistent with septic pedal arthritis. Diagnosis could be confirmed by radiography in chronic cases but this is cost-prohibitive in most practical situations. Arthrocentesis is rarely undertaken because there is only a small amount of pannus within the joint; rarely is there a large amount of fluid pus within the joint.

3 How long has this ram been lame? There is no obvious erosion of articular surfaces or osteophytosis on radiography (2.100b), but the soft tissue reaction (2.100a) would indicate that the infection has been present for 2-3 weeks at least.

4 What treatment would you recommend? Flunixin meglumine is injected IV before surgery. Lidocaine 2% solution (5-7 ml) is injected into the superficial vein running on the craniolateral aspect of the third metatarsal bone (recurrent metatarsal vein) after application of a strong rubber band tourniquet below the hock (IVRA). Analgesia is achieved within 2 minutes. The interdigital skin is incised as close to the infected tissue as possible and the incision extended for the full length of the interdigital space to a depth of 1.5 cm. A length of embryotomy wire is introduced into the incision and the medial digit removed at the level of mid P2. In chronic cases where there is extensive osteophytosis extending onto distal P1, excision through mid P1 is recommended. A melolin dressing is applied to the wound and a pressure bandage applied. Analgesics and antibiotics are administered for 4 days. The dressing is changed after 4 days.

Joint lavage through an indwelling catheter has been recommended as an alternative treatment and has the advantage of maintaining both digits, but this takes more time, is more expensive and takes longer for resolution of lameness.

CASE 2.101

1 Comment on the radiograph. There is obvious soft tissue swelling of the elbow region. The articular spaces of the shoulder and elbow joints are perhaps wider than normal, but comparison should be made with the contralateral normal joints. There is no convincing evidence of joint infection in this radiograph.

2 What action would you take? Clinical examination suggests joint involvement of the right shoulder and elbow joints despite lack of radiographic changes. The lamb has not responded to antibiotic therapy, although this may have been started too late. Euthanasia followed by necropsy reveals a pannus in both joints, with early articular cartilage erosion of the humerus (2.101b). Radiography is of very limited use in confirming a provisional diagnosis of early septic arthritis in young lambs; clinical examination is much more informative, bearing in mind that joint effusion is limited and the major inflammatory component is a pannus. Crepitus will not be appreciated, if at all, until there is significant articular cartilage erosion and osteophytosis, which may take 4-6 months. Lambs with polyarthritis that remain lame after appropriate antibiotic therapy should be euthanased for welfare reasons because they will not recover. Where Streptococcus dysgalactiae is the major joint pathogen, the most appropriate antibiotic therapy is procaine penicillin (15 mg/kg IM for 7-10 consecutive days) remembering that penicillin is a time-dependent antibiotic - duration of therapy not dose rate is the critical factor. A single injection of long-acting penicillin is

not an appropriate treatment. There is no advantage in administering a penicillin and streptomycin combination; indeed such preparations contain only two-thirds of the concentration of penicillin compared with a penicillin-only preparation. A single corticosteroid injection on the first day of antibiotic therapy reduces joint exudation, inflammation of the synovium and lameness.

CASE 2.102

1 What conditions would you consider? Sheep scab mite infestation (Psoroptes ovis); louse infestation; keds; severe dermatophilosis.

2 How would you confirm the diagnosis? Skin scrapings taken from the periphery of the lesion demonstrate large numbers of mites under ?100 magnification (2.102b). Lice and keds can be visualized on careful examination of the skin, but are not seen in these sheep.

3 What treatment would you administer? One injection of doramectin is effective against sheep scab mite infestation, but two injections of ivermectin 1 week apart are needed for scab treatment. Two injections of moxidectin 1%, 10 days apart, are needed for scab treatment. Subcutaneous injection of moxidectin 2% at the base of the ear provides 60 days protection against sheep scab.

Ivermectin provides no significant residual protection against reinfestation from a contaminated environment, therefore it is essential that sheep are not returned to the same pastures/buildings for at least 17 days post treatment. Although doramectin and moxidectin do have residual action against reinfestation, it would be prudent to apply this rule to all systemic endectocide treatments.

Dimpylate (diazinon), flumethrin and propetamphos-containing dips treat and prevent sheep scab, while high cis cypermethrin-containing dips are effective for treatment only if used a second time 14 days later. Treatment for sheep scab necessitates that sheep are immersed in the dip wash for 60 seconds with the head submerged twice. Sheep dipped in high cis cypermethrin-containing dips must not be returned to infested pastures after dipping because of the limited residual action against scab mites.

Occasionally, severely affected sheep may develop seizures during handling, caused by an anaphylactic reaction. These sheep should be treated with IV dexamethasone. Affected sheep recover in 15-30 minutes but further seizures are likely over the next few days if handled.

CASE 2.103

1 What are the possible causes of this problem? Reduced lamb birthweight can occur when placental development has been limited by competition in the uterus for caruncles, resulting in a reduced number of placentomes per fetus. This situation is not uncommonly encountered in multiple litters where the birth of twins with disproportionate weights (e.g. 5.5 kg versus 3.5 kg) probably indicates that three embryos implanted and underwent early fetal development, but one fetus failed to develop further and was resorbed. The limited number of caruncles available to the remaining fetus in the ipsilateral horn results in poor growth and a reduced birthweight compared with the co-twin, which developed without competition in the contralateral horn. While the placentomes can increase in size and blood flow, these compensatory mechanisms often fail to overcome their reduced number. Severe subacute fasciolosis has been associated with fetal resorption, a much reduced scanning percentage and low lamb birthweights. Inadequate energy supply during late gestation results in similar low birthweight within litters and a low ewe BCS (5-10% has failed to reveal any major problems in this author’s experience.

CASE 2.104

1 Describe the important features in the sonogram. The distal lobe is a well- encapsulated mass with an anechoic appearance containing multiple hyperechoic dots consistent with an abscess. Note the 1.5 cm distance from the probe head to the abscess capsule, representing thickened skin and subcutaneous oedema (see 2.104b).

2 What conditions would you consider (most likely first)? Sperm granuloma; epididymitis; orchitis. Sperm granulomas (2.104b) are a coincidental finding in rams several years after vasectomy. This ram was vasectomised 3 years previously and was left in the group to test you out!

3 What action would you take?

No action is necessary; the ram is in excellent condition and the scrotal contents are not painful.

The presence of a sperm granuloma does not appear to affect the function of a teaser ram despite testicular atrophy. Attempted collection of a semen sample by electroejaculation would be contraindicated.

CASE 2.105

1 What is the significant finding? There has been total resorption of perirenal fat, with the kidney now clearly visible. This contrasts markedly with a well-fed lamb where the kidney is embedded in fat (2.105b). The cause of fat mobilisation is starvation, whether due to poor dam milk supply or mismothering.

2 What other supporting evidence would you check for in the cadaver? In well-fed lambs there will be large milk clots in the abomasum. If the lamb has been artificially fed immediately before death, the milk may not have had time to clot and will be liquid.

3 What other supporting evidence would you check for on the farm? Hungry lambs are readily identified by their gaunt appearance. Colostrum, then milk, in the lamb's abomasum immediately caudal to the costal arch can readily be detected by gentle transabdominal palpation. Transabdominal ultrasonographic examination of the abomasum of neonatal lambs provides a reliable method to determine whether lambs have sucked.

Venous blood samples collected into lithium heparin vacutainers can be spun down in a microhaematocrit centrifuge and total plasma protein concentration determined using a hand-held refractometer. The plasma protein concentration of lambs that have not sucked sufficient colostrum is 60 g/l (6 g/dl) for lambs that have sucked adequate colostrum within the first 12 hours. Such tests are accurate, inexpensive and very informative.

Ewe nutrition during late gestation can be judged from BCSs. Lamb birthweight will also give an accurate assessment of late gestation ewe nutrition, with values >1 kg below normal indicative of dietary energy deficiency.

CASE 2.106

1 What conditions would you consider (most likely first)? Include: contagious pustular dermatitis virus and Dermatophilus congolensis causing ‘strawberry footrot'; granulation tissue following a deep skin cut; sheep pox (not UK).

2 What treatments would you administer? Procaine penicillin (15 mg/kg IM for 7-14 consecutive days) and topical antibiotic spray should be used to control the superficial secondary bacterial infection, but response to treatment is poor and may take several months. Remove both lambs from this pasture and isolate from the group to prevent spread. Housing is preferable; be aware of possible cutaneous myiasis in animals left at pasture. Healing takes many months and lesions may not completely resolve; marked enlargement of the drainage (popliteal) lymph node would raise concerns at the slaughter plant and could result in hindquarter/carcass condemnation.

3 What samples would you collect? Contagious pustular dermatitis virus can be demonstrated by direct electron microscopy of fresh lesions. Bacteriology of the skin lesions is of doubtful benefit as D. congolensis is a common skin commensal.

4 What preventive measures could be considered for next year? Disease is introduced into a flock by carrier sheep with no obvious skin lesions. Infection can remain viable in dry scab material for many months and is the likely reason for persistence of infection from year to year on the same premises. The benefit of vaccination is debatable and is undertaken by scarification of the inner thigh in lambs and the axillary region in ewes. The timing of vaccination is approximately 6 weeks before the anticipated occurrence of disease, which could not have been predicted in these purchased lambs of unknown health status. Care must be exercised during handling the live vaccine as it is affected by high temperatures and inactivated by disinfectants. Limit skin trauma by controlling thistles, gorse, etc. in pastures wherever possible.

CASE 2.107

1 How will you deal with this case? The vaginal prolapse is cleaned and replaced under low extradural block in the standing ewe. The first intercoccygeal space is identified by digital palpation during slight vertical movement of the tail, and a 1 inch 19 gauge needle directed at 20° to the tail, which is held horizontally. Correct position of the needle is determined by the lack of resistance to injection of 0.5-0.6 mg/kg of a 2% lidocaine solution and 0.07 mg/kg xylazine (equivalent to 2 ml of 2% lidocaine and 0.25 ml of 2% xylazine for an 80 kg ewe, respectively.

The vaginal prolapse almost always contains urinary bladder, which is emptied by gently elevating the prolapse relative to the vulva. This relieves the kink in the urethra and urine freely drains from the distended bladder. The much reduced size of the prolapse is then replaced by gentle pressure. Topical sugar is claimed to reduce the size of the prolapse and aid replacement.

A perivulval Buhner suture of 5 mm umbilical tape is inserted and tied with an opening of two fingers width to allow urination. The ewe is treated with procaine penicillin for 3-5 consecutive days. The suture should be untied after a few days

and not delayed until there are signs of first stage labour (2.107b).

2 What is the future management of this sheep? Risk factors for vaginal prolapse include excessive body condition, housing, lack of exercise, multigravid, high-fibre diets and lameness; however, these risk factors apply to the majority of sheep that are not affected by this condition. Affected ewes must not be kept for future breeding, as recurrence is common.

CASE 2.108

1 Describe the important sonographic findings. The liver is not homogeneous but contains many hyperechoic dots with distant shadowing consistent with inflammatory cell accumulations caused by migrating immature flukes. The ultrasound findings are consistent with subacute fasciolosis.

2 What tests would you undertake? Raised GGT and GLDH concentrations (5-30-fold) are consistent with hepatic damage caused by migrating flukes (2.108b). Changes in albumin and globulin concentrations are not disease-specific. The coproantigen ELISA test detects digestive enzymes produced by migrating (late immature) and adult flukes, which are released into the bile and detected in faeces, thereby confirming active infection. Fluke infection can be detected after 3-4 weeks but more reliably after 6-9 weeks, 2-3 weeks before eggs can be detected in faeces

3 What treatment(s) would you administer? Treat all sheep in the flock with triclabendazole immediately and 6 weeks later with closantel in case of triclabendazole resistance. Use a different fluke treatment in spring, which need only be effective against adult flukes, thereby further reducing the risk of selecting for flukicide resistance.

4 What could be a major consequence of this problem? Fetal death/resorption causing high barren rates and much lower litter size is reported after severe subacute liver fluke infection. Indeed, where disease has not been seen before, very poor scanning results may be the first indication that there is a serious liver fluke problem on the farm. This problem may be limited to only one group of sheep depending on its autumn/winter grazing.

CASE 2.109

1 What is your diagnosis (most likely first)? The most likely conditions to consider include: delayed swayback; vertebral empyema C1 to C6; Streptococcus dysgalactiae infection of the atlanto-occipital joint causing cord compression, although much older than usual cases; injection site infection tracking to the cervical spinal canal; muscular dystrophy (white muscle disease).

In the delayed form of swayback (enzootic ataxia) the lambs are normal at birth but show progressive weakness of the hindlegs from 2-4 months of age. Signs are often first noted during gathering or movement when affected lambs lag behind the remainder of the flock. The hindlegs are weak with reduced muscle tone and reflexes, and show muscle atrophy. Lumbar CSF protein concentration is normal, ruling out significant cord compression from an inflammatory focus.

2 What treatments would you administer? There is limited evidence that copper supplementation of lambs with enzootic ataxia slows the progress of the condition; treatment was unsuccessful in this case.

3 How could you confirm your diagnosis? Delayed swayback was confirmed by histopathological examination of the spinal cord after euthanasia for welfare reasons.

4 What preventive measures could be adopted? Prevention of swayback by copper supplementation of ewes during mid-pregnancy must very carefully consider the prevalence of confirmed or suspected swayback cases in the flock, breed of sheep, supplementary feeding during gestation, whether the sheep will be housed during late gestation, and the geological area including soil analysis.

CASE 2.110

1 Comment on the major radiographic findings. There is marked soft tissue swelling of the interdigital space extending over the abaxial aspect of the lateral claw. There is considerably widening of the articular space of the distal interphalangeal joint, with effective disarticulation and erosion of articular surfaces. There is also osteophytosis of distal P1, and more so involving P2.

2 What condition would you consider? Septic pedal arthritis with disarticulation of the distal interphalangeal joint.

3 How long has this ram been lame? This degree of bone destruction/ reaction would likely have taken 2 months at a conservative estimate, during which time the ram would have been severely lame (2.110b).

4 What treatment would you recommend? Digit amputation through distal P1 (see Case 2.100 for a detailed description of the procedure).

CASE 2.111

1 What conditions would you consider (most likely first)? Vertebral empyema affecting the spinal cord in the region from T2 to L3; sarcocystosis; trauma; nutritional myopathy (selenium/vitamin E deficiency/white muscle disease); delayed swayback.

2 How would you confirm your diagnosis? A lumbar CSF sample collected under local anaesthesia reveals a protein concentration of 1.7 g/l, with a slight increase in white cell concentration comprised almost exclusively of neutrophils. A diagnosis of a compressive lesion of the spinal cord is based on >4-fold increase in lumbar CSF protein concentration (normal range leading to involuntary culling. This pathology has not been reported to date in other breeds of sheep, although difficulties accessing the temporomandibular joint at necropsy limits the necropsy data available for analysis.

CASE 2.113

1 What might this structure be (most likely first)? Toe fibroma; keratoma; squamous cell carcinoma; footrot. A toe fibroma is comprised solely of exuberant granulation tissue.

2 What factors contribute to this condition? Toe fibromas usually arise from overzealous hoof trimming exposing an area of corium at the toe (2.113b) coupled with misuse/overuse of formalin footbaths exacerbating granulation tissue formation. In some cases, footrot can play an important role in exposing and damaging the corium.

3 What would you do to correct this problem? A toe fibroma is comprised solely of exuberant granulation tissue without a nerve supply, therefore it can be excised level with the sole using a No. 22 scalpel blade without the need for local anaesthesia. Melolin, or similar topical dressing, must be applied directly onto the exposed corium, followed by abundant cotton and a pressure bandage.

A second pressure bandage may be needed after 3-4 days in some cases. The role of cautery (hot disbudding iron) and/or copper sulphate to prevent regrowth of the fibroma is controversial

because

further damage to the corium delays epithelialisation.

4 What advice would you offer about future control? Foot trimming is not recommended in the treatment of footrot. When undertaken, for example to pare out a white line abscess, paring the hoof horn must not expose the sensitive corium. oxytetracycline or tilmicosin is the

Topical antibiotic spray with parenteral preferred treatment for footrot; foot bathing in formalin solutions is restricted to the prevention of footrot. If a small area of the corium is exposed, the lesion should be sprayed topically with oxytetracycline aerosol and not put through a footbath. If a large area of the corium is exposed, a pressure bandage should be applied for 4-5 days and the foot rechecked.

CASE 2.114

1 What is your differential diagnosis? Fetal death/autolysis; undetected dystocia/ dead lambs; uterine torsion/dead lambs; intestinal torsion; peritonitis.

Potential abortifacient agents that could contribute to this clinical presentation include: salmonellae including S. montevideo and S. typhimurium; Chlamydophila abortus (enzootic abortion of ewes; EAE). Other common causes of abortion (Campylobacter fetus intestinalis, Listeria monocytogenes, Pasteurella spp.) cause abortion often without signs of illness in the ewe.

2 What further tests could be carried out? Transabdominal ultrasound examination of the uterus can be undertaken to check the integrity of the uterus and whether the lambs are alive (fetal heartbeat). Ultrasound examination of the abdomen will also identify fluid-filled loops of intestine in cases of torsion.

3 What treatment/action would you consider? The ewe could be treated symptomatically with IV oxytetracycline and an NSAID. However, the prognosis is hopeless, therefore the ewe should be euthanased for welfare reasons. Fetal death and autolysis are confirmed at necropsy (2.114b).

4 What investigations would you undertake? The farmer was advised to isolate aborting ewes immediately and for up to at least 6 weeks depending on laboratory findings. The farmer was also advised regarding the zoonotic risk of some of the common causes of abortion and to adopt strict personal hygiene when handling sick sheep.

The fetuses and placentae, or fetal stomach contents and samples of placentae, should be sent to the nearest diagnostic laboratory. A blood sample collected for EAE and Toxoplasma serology could be collected before euthanasia of the ewe. S. typhimurium was isolated in pure culture from the fetal stomach contents in this case.

CASE 2.115

1 What conditions would you consider (most likely first)? Trichostrongylosis, particularly Trichostrongylus vitrinus; other causes of parasitic gastroenteritis; liver fluke; yersiniosis; salmonellosis.

2 How would you investigate this problem? Faecal egg counts (McMaster technique) are routinely used to aid diagnosis of nematode infestations. As a general rule, a trichostrongyle egg count of 400 epg is considered moderate, while 700-1,000 epg is considered high and worthy of anthelmintic treatment. However, the faecal egg count may not always accurately reflect potential parasite damage because disease can be caused by developing larvae. Liver fluke infections do not usually cause diarrhoea.

3 What action would you take? There are five different anthelmintic groups that could be used to treat trichostrongylosis:

• 1-BZ: benzimidazoles, probenzimidazoles (white wormers).

• 2-LM: imidazothiazoles, tetrahydropyrimidines (yellow wormers). Levamisole and tetramisole are imidazothiazoles. Morantel and pyrantel are tetrahydropyrimidines.

• 3-AV: avermectins, milbemycins (clear wormers). Preparations that con­tain avermectins include doramectin and ivermectin; moxidectin is an example of a milbemycin.

• 4-AD: monepantel (orange wormers).

• 5-SI: derquantel and abamectin (dual active) (purple wormers).

Resistance to benzimidazoles has been recognised as being widespread in the UK and resistance to all members of groups 1-3 (‘triple or multiple resistance') has been identified since 2001. It would be prudent to do a pooled faecal worm egg count 7-10 days after treatment to check anthelmintic efficacy. Group 4 and 5 anthelmintics are generally held in reserve should resistance problems arise to the other three groups.

CASE 2.116

1 How will you deal with this case? Administer a low extradural block by identifying the first intercoccygeal space by digital palpation during slight vertical movement of the tail. A 25-40 mm 19 gauge needle is directed at 20° to the tail, which is held horizontally. The correct position of the needle is determined by the lack of resistance to injection of 1.5 ml of 2% lidocaine (0.5-0.6 mg/kg) and 0.2 ml xylazine (Rompun 2%®, 0.07 mg/kg) for a 60 kg ewe. The uterine prolapse is replaced 5-10 minutes after combined sacrococcygeal extradural injection. It is important not to penetrate the vaginal mucosa when inserting the Buhner suture of 5 mm umbilical tape.

The ewe is injected with dexamethasone to reduce perivulval oedema. Procaine penicillin (15 mg/kg IM for 5 consecutive days) is given to counter bacterial infection. NSAIDs, such as ketoprofen or flunixin meglumine, could also have been given for their analgesic properties, but extradural lidocaine gives immediate analgesia and the xylazine component provides analgesia for up to 36 hours. The Buhner suture is removed after 2-3 days. The lamb should be monitored closely because it may require supplementary milk over the next few days.

Unlike vaginal prolapse cases, prolapse of the uterus in subsequent pregnancies is uncommon and culling is not necessary.

CASE 2.117

1 List the potential advantages of management systems using a Vasectomised ram. Vasectomised rams are widely used to induce ovulation and synchronise oestrus in ewes before the introduction of fertile rams, thereby compacting the lambing period, optimising seasonal labour and reducing the consequences of disease build-up as the lambing season progresses. It is common practice to introduce the vasectomised ram for 1 week starting 2 weeks before the breeding season. This management practice will generally induce ovulation in ram-responsive ewes within 2-3 days, with normal behavioural oestrus around 17 days later (i.e. around 6 days after the introduction of fertile rams).

2 What analgesia/anaesthesia would you employ? A NSAID is given IV before surgery. Spinal analgesia is induced using an extradural lidocaine injection (3 mg/kg) at the lumbosacral site.

3 How is the vas deferens identified during surgery? The spermatic cord is exteriorised following blunt dissection and the vas deferens localised medially within the spermatic cord between the thumb and index finger. The vaginal tunic is nicked with the scalpel blade point (2.117) and a 6 cm length of vas deferens is ligated twice and the 4-5 cm section between the ligatures removed.

4 How is successful vasectomy confirmed? The two lengths of vasa deferentes are submitted for histological confirmation in correctly labelled containers of formal saline. Alternatively, material contained within the excised material is expressed onto a microscope slide to check for spermatozoa.

5 What is the minimal interval between vasectomy and introduction of the teaser ram to a group of ewes? There are no published guidelines; 2 weeks would seem a safe interval, as significant sperm survival within the remaining sections of vasa deferentes is limited.

CASE 2.118

1 What conditions would you consider (most likely first)? Vertebral empyema affecting the spinal cord in the region from T2 to L3; delayed swayback; sarcocystosis; trauma/fracture.

2 What is the origin of this problem? The infection has originated from bacteraemia, with initial localisation in an articular facet and spread to the vertebral body causing osteomyelitis/empyema with subsequent compression of the spinal cord.

3 What is the significance of no ticks on the lamb? On many hill farms, vertebral body abscessation and polyarthritis are not uncommon sequelae to tick-borne fever and tick bite pyaemia, but this farm is not in a tick area and there are no ticks on this lamb. Septic foci are not usually found to be the potential source of the bacteraemia, except for minor superficial wounds associated with castration, tail docking and ear tags.

4 What treatments would you now administer? Treatment of vertebral empyema with antibiotics is never successful because of the extensive bone destruction

present when clinical signs appear (2.118b, arrow). The lamb must be euthanased for welfare reasons once a definitive diagnosis has been established by demonstrating a >4-fold increase in lumbar CSF protein concentration (normal range cerebral abscess.

2 How would you investigate this problem? Serum vitamin B₁₂ analysis. Response to vitamin B₁₂ injection and oral cobalt supplementation. As a general guide, a growth response is expected when the mean plasma vitamin B₁₂ concentration falls below 500 pg/ml, and is likely to be significant below 250 pg/ml.

3 What treatment will you administer? Treatment is more quickly effected by a combination of IM injection of vitamin B₁₂ and drenching with up to 1 mg/kg bodyweight of cobalt sulphate than with oral supplementation alone. Thereafter, monthly drenching with cobalt sulphate should ensure normal weight gain.

4 How would you prevent this problem recurring next year? Oral cobalt supplementation is very cheap and certain anthelmintic preparations belonging to Group 1-BZ and Group 2-LM may already contain a cobalt supplement (‘SC’ preparations). Monthly dosing from around 3 months old should supply sufficient cobalt to growing lambs in most situations.

CASE 2.123

1 What is the cause of this condition? Woolslip occurs sporadically in sheep and most commonly starts 2-4 weeks after recovery from ovine pregnancy toxaemia, infectious causes of abortion/metritis or other serious disease. Surprisingly, the sheep are typically in very good body condition when the fleece is being shed and despite previous serious illness.

2 What action would you take? There is no treatment and the new fleece is normal in appearance, although there will be no requirement for shearing that year. Adopt preventive strategies (e.g. vaccinate for infectious causes of abortion where possible) and correct nutrition to prevent pregnancy toxaemia etc.