Guinea pigs, chinchillas, and degus

Many of the pet rodents presented to the veterinarian belong to the group known as hystri- comorphs. The following species are the most common as household pets:

• Guinea pig (Cavia porcellus)

• Chinchilla (Chinchilla lanigera)—the most common chinchilla species kept as pets

• Short-tailed chinchilla (C.

• Degu (Octodon degus)

Consultation and handling

Hystricomorph rodents are prey animals, so some may respond poorly to handling.

Although both rabbits and guinea pigs are social animals, generally the keeping of guinea pigs with rabbits is not recommended because:

1. Rabbits are often aggressive to guinea pigs and may bite and harass them. Much of this activity occurs at night and may not be noticed by the owner.

2. Guinea pigs require dietary vitamin C (see Nutritional Disorders) and may suffer hypovitaminosis if fed on commercial rabbit food only.

3. Rabbits harbor Bordetella in their respiratory tract, which can be a significant respiratory pathogen in guinea pigs.

Sexing of chinchillas can be problematic as the female has a pronounced genital papilla that can be easily mistaken as a penis. The vulva lies immediately caudal to this papilla (Fig. 3-1).

Nursing care

For general concepts, see Nursing Care in Chapter 2.

Fluid therapy

Small rodents by virtue of their size and the high risk of predation are forced to obtain most of their water from preformed (food) and metabolic sources. Dehydration can be critical for hys- tricomorph rodents, especially at higher environmental temperatures. For an adult chinchilla, 55.5% of its daily water loss is as urine, 16.7% evaporates from its skin, 22.2% evaporates from its lungs, and 5.6% is lost in the feces. Therefore, 38.9% of its water loss is insensible.

Fluids can be given SC, IP, or IO—indeed, if there is marked dehydration, then IP or IO is preferable to SC.

Jugular catheterization can be attempted in all species, but it is difficult and may result in respiratory embarrassment. Many of these sites may also require anesthesia and surgical cutdown. In hypovolemic patients, vascular access may be impossible. It is better to consider either IP or IO administration.

Thermoregulation and hypothermia

Use a heat source, such as an electric heat mat plus insulation such as silver foil (reduces heat lost by conduction) and bubble wrap (reduces heat lost by convection). Pay particular atten­tion to the pinnae of chinchillas as these are significant organs of heat loss. Alternatively, maintain in warm air (e.g., incubator) or use a commercial medical warm air generator. If body temperature falls too low, consider the risk of enterotoxemia following massive gut bacterial die-off.

Nutritional status

Many small mammals are presented as emergencies after a prolonged period of ill health that will have affected their food intake (e.g., chinchillas and guinea pigs suffering from undiag­nosed chronic dental disease). These rodents are often hypoglycemic—test with a commercial glucometer on a small sample of blood—and IV or IP glucose can be given to these cases once identified.

Analgesia

Anesthesia

Beware of subclinical respiratory infections.

Keep the animal warm; as they have a large surface area compared with volume this results in significant heat loss during surgery, and hypothermia acts as a general depressant and is also immunosuppressive. Merely applying insulation such as bubble wrap is often insufficient—inactive, anesthetized rodents are not generating heat and you may be insulating it from a higher ambient temperature. Place these animals onto a heat mat, onto which is placed an absorptive towel or other material to both protect the mat from becoming wet and reduce the slight risk of localized burns.

Gaseous anesthesia

1. Masking down or placing in an induction chamber is often the safest way to induce anesthesia in a hystricomorph rodent.

2. Guinea pigs will often hypersalivate in response to isoflurane; atropine at 0.1 to 0.2 mg/kg SC may reduce this.

3. Intubation is extremely difficult due to the narrow caudal pharynx, large tongue, and small glottis. Makeshift endotracheal tubes using intravenous catheters readily block with respiratory secretions. It is often more expedient to maintain on a mask or intubate by a tracheotomy if thought necessary.

Parenteral anesthesia

1. Ketamine/medetomidine/butorphanol given IM simultaneously:

a. Ketamine at 10 mg/kg

b. Medetomidine at 0.1 mg/kg

c. Butorphanol at 1.5 mg/kg

2. At end of procedure, reverse medetomidine with atipamezole at 0.75 mg/kg IM, SC.

3. Administering metoclopramide (0.5 mg/kg SC or PO every 6 to 8 hours) postoperatively will help to prevent a postsurgical ileus, especially following painful or abdominal surgery.

4. Monitor feeding and fecal output for 24 hours following surgery.

Cardiopulmonary resuscitation

Respiratory arrest

1. Administer 100% oxygen.

2. Assist ventilation—compress thorax at around 60x/minute.

3. Doxapram sublingual or at 10 mg/kg IV or IP. Note: This will increase the animal's oxygen demand.

4. If appropriate, give atipamezole.

Cardiac arrest

1. As for respiratory arrest.

But also:

2. Compress thorax at around 90x/min.

3. If asystole—give epinephrine at 0.1 mg/kg IV of 1 : 10,000; 0.003mg/kg IV (guinea pig).

4. If ventricular fibrillation—lidocaine (lignocaine) at 1 to 2 mg/kg IV.

Skin disorders

Chinchillas have extremely dense fur, an attribute that has probably been enhanced by arti­ficial selection. This may be why external parasites are uncommon in the chinchilla.

Fig 3-2. Severe self-inflicted trauma in a guinea pig, pruritus secondary to Trixacarus.

Pruritus

• Guinea pig

• Trixacarus caviae (sarcoptid mite) (Fig. 3-2): Commonly associated with immunosuppression associated with pregnancy/parturition

• Other sarcoptids Sarcoptes muris, Notoedres muris

• Chirodiscoides caviae and Myocoptes musculinus (fur mites)

Alopecia

• Parasitic

• Mites:

- Trixacarus caviae, the sarcoptid mite (guinea pigs). Commonly associated with immunosuppression associated with pregnancy/parturition

- Other sarcoptids Sarcoptes muris, Notoedres muris

- Cheyletiella parasitovorax

- Chirodiscoides caviae and Myocoptes musculinus (fur mites)

- Demodex caviae (significance uncertain)

- Storage mites: Acarus farris (Linek and Bourdeau 2005)

• Lice:

- Gyropus ovalis, Gliricola porcelli (chewing lice), and Trimenopon hispidum (sucking louse). Usually asymptomatic; if heavy infestation, may cause alopecia and a rough coat.

• Bacterial

• Pyoderma (often secondary infection from scratching)

• Salmonellosis (Singh et al 2005)

• Fungal

• Dermatophytosis (Trichophyton mentagrophytes, Microsporum spp.); can be asymptomatic

• Scopulariopsis brevicaulis, usually asymptomatic

• Nutritional

• Hypovitaminosis C (rough hair coat/hair loss in guinea pigs)

• Fatty acid deficiency (chinchillas—see Nutritional Disorders)

• Pantothenic acid deficiency (chinchillas); may be complicated by zinc deficiency (see Nutritional Disorders)

• Other

• Fur slip: Improper handling/antipredator response seen in chinchillas

• Cystic ovarian disease (guinea pigs—see Reproductive Tract Disorders)

• Hyperadrenocorticism (Cushing disease—see Endocrine Disorders)

• Barbering/fur chewing (for chinchillas—see also Endocrine Disorders); may be linked to lack of dietary fiber

• Very low environmental humidity, such as central heating (chinchillas)

• Linked to intensive breeding of female guinea pigs

Scaling and crusting

• Dermatophytosis (Trichophyton mentagrophytes, Microsporum spp.)

• Scopulariopsis brevicaulis

Seborrhea

• Dermatophytosis (Trichophyton mentagrophytes, Microsporum spp.)

Sebaceous secretions

• Excessive accumulation around the perineal and perianal region in older guinea pig boars

Erosions and ulceration

• Pododermatitis (Staphylococcus aureus and S. epidermidis)

• Cryptococcus neoformans

• Frostbite (chinchillas)

Swellings, nodules, and nonhealing wounds

• Abscess

• Mycobacteriosis

• Aural hematoma (chinchillas)

• Hypovitaminosis E (chinchillas; distinct swellings on abdomen—see Nutritional Disorders)

• Cutaneous cysts

Changes in pigmentation

• Yellow ears (chinchillas—see Nutritional Disorders)

Neoplasia

• Trichofolliculoma

• Fibrosarcoma

• Sebaceous adenoma

• Lipoma

• Mammary fibroadenoma

• Mammary fibrocarcinoma

• Mammary adenocarcinoma

• Cutaneous papilloma of the foot pad

• Cutaneous hemangioma (Hammer et al 2005)

Other abnormalities

• Bites to pinnae (chinchillas, guinea pigs kept with rabbits)

• Cotton fur syndrome (chinchillas—see Nutritional Disorders)

• Degloving of tail in chinchillas and degus (improper handling)

Findings on clinical examination

• Areas of alopecia—may be bilateral (hormonal) or patchy (fatty acid deficiency, pantothenic acid deficiency in chinchillas)

• Swellings, often firm consistency even if abscess. Displacement of normal outline of coat may indicate swelling.

• Texture of hair coat may alter, becoming rougher.

• Cuts and abrasions: these may be self-inflicted in cases of severe pruritus. In guinea pigs, such lesions tend to be over the shoulders and back of the neck where the guinea pig scratches with its hind claws.

• Extreme pruritus

• Seizures may follow episodes of extreme pruritus (guinea pigs with ectoparasites).

• Pododermatitis

• Ulcerations, erythema, calluses, nail distortions, and abnormalities. Related lymph nodes may be enlarged (especially in guinea pigs).

• Systemic signs

• Linked to amyloidosis in liver, kidneys, pancreas, spleen, adrenal glands

• Overgrown claws

• Degloved tip of tail (chinchillas and degus)

Investigations

1. Radiography

a. Pododermatitis—often underlying osteoarthritis

2. Routine hematology and biochemistry

a. Eosinophilia (ectoparasitism)

3. Bacteriology and mycology: hair pluck or swab lesions for routine culture and sensitivity

4. Fecal swab for salmonellosis

5. Cytology

a. Fine-needle aspirate followed by staining with rapid Romanowsky stains

b. Gram stain

6. Microscopy: Examine fur pluck, acetate strips, or skin scrapes to affected area and examine for ectoparasites.

7. Examine teeth. Rodents with dental disease may have difficulty grooming normally.

8. Biopsy obvious lesions.

9. Ultraviolet (Wood's) lamp—positive for Microsporium canis only (not all strains fluoresce).

10. Endocrine analysis: thyroxine, estradiol (see Endocrine Disorders)

11. If barbering suspected, examine hair under microscope to see if chewed; separate from other animals; supply extra hay.

TreatmentZspecific therapy

• Treat for any ectoparasites

• Ivermectin at 200 pg/kg SC or as topical application (Xeno 450, Genitrix Beaphar Anti-Parasite Spot-On for Small Animals, USA); 3 treatments given 2 weeks apart

• Imidacloprid (Advantage, Bayer) applied as a 40 mg spot-on treatment

• 40 mg imidacloprid/4.0 mg moxidectin (Advocate, Advantage Multi, Bayer USA) at 0.1 mL per guinea pig (Beck 2007)

• Permethrin applied as either a dusting powder or shampoo

• Chirodiscoides caviae

• Ivermectin at 0.4 to 0.5 mg/kg SC, repeat after 2 weeks

• Selamectin at 12 mg/kg topically, 2 treatments, 2 weeks apart

• Demodex

• Ivermectin at 0.4 to 0.5 mg/kg SC or topically every 7 days

• Amitraz washes at 250 mg/L every 7 days

• If very pruritic, consider use of NSAIDs.

• Pododermatitis

• Chronic infections lead to persistent swelling of the feet and gross abnormalities of the feet.

• Note: May also induce amyloidosis in internal organs (see Hepatic Disorders, Pancreatic Disorders, and Endocrine Disorders)

• Amelioration of underlying factors (e.g., removal from mesh flooring)

• Topical and systemic antibiosis

• Analgesia, such as meloxicam at 0.3 mg/kg PO s.i.d.

• Amputation of chronic, resistant infections to prevent risk of amyloidosis

• Abscessation

• Surgical removal (with swab for culture and sensitivity) plus appropriate antibiosis

• Lancing, debriding, and cleaning of abscesses give poor results compared to surgical resection.

• Salmonellosis

• Vitamin C supplementation (1 g/kg feed) or 50 to 100 mg/kg PO for guinea pigs

• Appropriate antibiosis

• Cysts: Surgical resection; may respond to local draining

• Dermatophytosis, Scopulariopsis, and Cryptococcus

• Griseofulvin at 15 to 25 mg/kg PO once daily for 4 weeks. Toxic to immature and fetal guinea pigs, so use on adult, nonpregnant guinea pigs only.

• Miconazole/chlorhexidine (Malaseb) shampoo—bath once daily

• Itraconazole at 15 mg/kg PO given daily to effect (Van Gestel and Engelen 2004)

• Lufenuron was found to be ineffective (Van Gestel and Engelen 2004).

• Often found in young guinea pigs (Mycoplasma pulmonis

• Pasteurella

• Pneumocystis jiroveci (usually asymptomatic except with severe immunosuppression)

• Pseudomonas

• Streptobacillus moniliformis

• Streptococcus equi Zooepidemicus (pleuritis, hydrothorax, pericarditis)

• Streptococcus pneumoniae

• Streptococcus pyogenes

Fungal

• Histoplasma capsulatum (see Systemic Disorders)

Protozoal

• Toxoplasma gondii (see Neurologic Disorders)

Nutritional

• Hypovitaminosis C (see Nutritional Disorders)

Neoplasia

• Bronchogenic and alveologenic papillary adenomas (may be secondary to foreign body inhalation)

Other noninfectious problems

• Trauma (improper handling)

• Pneumothorax

• Diaphragmatic hernia

• Gastric tympany/torsion (see Gastrointestinal Tract Disorders)

• Heat stress (see Systemic Disorders)

• Dental disease (may resemble upper respiratory tract disease in chinchillas; see Dental Disorders)

• Choking (especially chinchillas)

• Cardiovascular disease (see Cardiovascular and Hematologic Disorders)

• Inappropriate bedding—wood shavings and sawdust can be a source of irritant essential oils.

Findings on clinical examination

• Dyspnea/tachypnea

• Open-mouth breathing

• Cyanosis

• High temperature

• Increased respiratory sounds

• Anorexia

• Weight loss

• Severe distress (choking)

• Conjunctivitis

• Chlamydophila rarely causes respiratory disease other than conjunctivitis; however, it can occur alongside bacterial pneumonia.

• Nasal discharge

• Vaginal discharge from metritis (guinea pigs with bordetellosis). Pregnant sows may abort.

• Swollen submandibular lymph nodes (S. moniliformis)

Investigations

1. Radiography

a. Lateral and dorsoventral (DV) radiographs

2. Routine hematology and biochemistry

a. Serology for Chlamydophila, Bordetella, adenovirus, Sendai virus, SV5, PVM, Mycoplasma pulmonis

3. Polymerase chain reaction (PCR) for Chlamydophila

4. Culture and sensitivity

5. Cytology

a. Transtracheal wash

b. Gram stain

6. Pleural tap and cytology

7. Endoscopy

8. Ultrasonography

9. Biopsy

a. Intranuclear inclusions (adenovirus)

10. Necropsy

Management

1. Supplement with vitamin C (guinea pigs, degus).

2. Parenteral fluids

3. Gentle soaking and removal of encrusted oculonasal discharges

4. Provide oxygen via mask or chamber.

5. Covering or specific antibiosis. Consider nebulization.

6. Syringe feeding (beware aspiration pneumonia)

7. NSAIDs (e.g., meloxicam 0.3 mg/kg PO s.i.d.) may reduce lung damage.

8. Mucolytics such as bromhexine and N-acetylcysteine may be useful.

9. Change bedding to paper-based substrate.

TreatmentZspecific therapy

• Bordetellosis

• Appropriate antibiosis

• Note: It is found asymptomatically in the upper respiratory tract of rabbits, which may therefore act as a reservoir of infection for guinea pigs when kept with rabbits.

• Vaccination with canine Bordetella vaccine at 0.2 mL per individual either SC or PO; repeat after 2 to 3 weeks, then give annual or 6-monthly booster according to risk (Huerkamp et al 1996).

• Streptococci

• Appropriate antibiosis

• S. pyogenes may be spread by biting insects.

• S. pneumoniae is spread by aerosol transmission.

• Sendai virus, SV5, and PVM are usually asymptomatic.

• Adenovirus: Treat symptomatically.

• Mycoplasmosis

• Appropriate antibiosis

• Choking

• Often die before treatment initiated

• Remove or dislodge foreign body (often food item) wedged over glottis.

Dental disorders

Permanent dental formula of the guinea pig and chinchilla For guinea pigs, the maxillar to mandibular ratio is around 1 : 2 (i.e., the mandibular incisors as viewed from the front should be twice the length of the maxillary incisors). Guinea pigs also have an oblique occlusal plane on the cheek teeth of around 40 degrees.

I:-, C:-, PM:-, M :³

10 13

Nutritional

• Lack of long fiber (e.g., hay) in diet

• Hypovitaminosis C (guinea pigs, possibly degus—see Nutritional Disorders)

• Inappropriate nutrition

Neoplasia

• Oral neoplasia causing differential wear

• Macrodontia (possibly odontomas—guinea pigs; see Fehr 2014)

Other noninfectious problems

• Fractured incisors (trauma)

• Congenital malocclusion

• Genetic predisposition

Findings on clinical examination

• Chinchilla and degu incisor teeth are naturally highly colored orange or yellow; this often fades with dental disease. Such fading may indicate hypovitaminosis A (see Nutritional Disorders).

• Incisor malocclusion

• Chewing in rodents involves a significant rostrocaudal movement of the mandibles; therefore, the lower incisors in particular are naturally quite long. This should not be mistaken for an abnormality. Compare where possible with another individual.

• Mandibular swellings (unilateral or bilateral) due to bone remodeling to accommodate tooth root overgrowth

• Maxillary swellings rostral to eye; painful on palpation—maxillary root overgrowth (especially chinchillas)

• One or more incisors shortened or fractured

• Excessive salivation/moist fur on chin and ventral neck (slobbers)

• Weight loss

• Anorexia

• Ectoparasitic disease

• Dacryocystitis/conjunctivitis

• Seizures (due to hypoglycemia)

Investigations

1. Otoscopic examination of oral cavity

a. Normal guinea pig or chinchilla always has a significant amount of food/ cecotrophic material in its mouth obscuring the dental arcades; if this is not the case then it is likely to be eating very poorly.

b. Lingual tilting of mandibular cheek teeth and buccal tilting of maxillary cheek teeth (Fig. 3-3)

c. The mandibular premolars may form a partial or complete arch over the tongue (guinea pig).

d. Otoscopic examination does not constitute a complete examination of the oral cavity as structures at the back of the pharynx can be difficult to see due to its depth and the large size of the tongue.

Fig 3-3. Lingual spurs on the lower premolars and molars of a chinchilla.

Fig 3-4. Lateral radiograph of a chinchilla with dental disease. Note the divergence of the maxillary tooth roots and the (palpable) bony remodeling of the mandibles associated with cheek tooth root overgrowth.

e. Spurs on cheek teeth. Often rostral facing on first lower premolars (chinchillas, degus)

f. Ulceration of tongue

g. Purulent material in mouth

2. Radiography

a. Lateral and DV views of skull. Note: Skulls often appear osteoporotic (Figs. 3-4 and 3-5).

Fig 3-5. Explanatory diagram of skull shown in Figure 3.4.

b. Left and right lateral oblique views of skull to allow assessment of individual tooth roots. Any divergence of maxillary or mandibular tooth roots away from each other suggests abnormal root elongation.

c. The mandibles can also be isolated by an open-mouth technique where the animal is placed in sternal recumbency and the mouth opened to its full extent by a bandage placed behind the upper incisors and pulled caudally, with the x-ray beam centered on the molars.

d. The maxillae are similarly investigated by placing the animal in dorsal recumbency with a roll under the neck, the nose positioned parallel to the plate, and the beam again centered on the molars.

e. Contrast study on nasolacrimal ducts; difficult in small hystricomorphs

3. Routine hematology and biochemistry

4. Culture and sensitivity

a. Aerobic and anaerobic culture of abscesses

5. Examination of oral cavity under general anesthesia (GA)

6. Endoscopy

Management

1. Chronic cases often cachexic—may need parenteral fluid support

2. Check blood glucose levels: guinea pig (3.36 to 7.8 mmol/L), chinchilla (3.36 to 6.72 mmol/L).

3. Syringe feeding with commercial feed suspensions (e.g., Oxbow Critical Care or Science Recovery Diet from Supreme Petfoods). May require nasogastric tube or tube feeding

4. Flushing of nasolacrimal ducts where possible

5. Only use antibiotics if indicated. Many cases do not require their use, which can be counterproductive.

6. Gut motility modifiers

7. Metoclopramide at 0.5 mg/kg SC or PO every 6 to 8 hours

8. Cisapride 0.5 mg/kg PO s.i.d. or b.i.d.

TreatmentZspecific therapy

• Regular coronal reduction

• Always burr overgrown incisors in preference to clipping due to risk of fracture, pulpal hemorrhage, and infection.

• For cheek teeth, this will likely necessitate heavy sedation or GA. “Conscious” dental work on the cheek teeth is stressful to the rodent and risks serious trauma to the oral cavity and spine.

• Often coronal reduction alone is insufficient; often by the time of presentation, dental disease has progressed to a quite advanced stage.

• Use of a dental drill or equivalent is essential; dental spurs can be clipped but the teeth must be burred down. Clipping is likely to fracture the tooth.

• Incisor extraction—likely to be achieved by extraoral approach

• Cheek teeth extraction—likely to be achieved by extraoral approach and burring of the apical area to attempt complete destruction of the tooth. Regrowth is not uncommon even after apical burring.

• Surgical debridement of tooth root abscesses including removal of infected bone and affected tooth roots, followed by:

• Packing with antibiotic-impregnated methylmethacrylate (bone cement or similar) and/or marsupialization, leaving ostium for recurrent povidone-iodine/antibiotic application during second-intention healing.

• Antibiosis

- Usually a broad-spectrum antibiotic such as enrofloxacin at 5 mg/kg PO s.i.d. or co-trimoxazole at 30 mg/kg PO b.i.d. plus

- Anaerobic antibiosis (e.g., metronidazole at 20 mg/kg PO s.i.d.)

• Drilling out of tooth root apices to initiate tooth root death where extraction is not viable. Note: Aggressive dental work in guinea pigs can trigger neuronal degeneration of afferent nerves in the periodontal ligament with subsequent degeneration of the mesencephalic trigeminal nucleus, resulting in dysphagia, postural abnormalities, and death (Azuma et al 1999, Kimoto 1993). See Neurologic Disorders and Cardiovascular and Hematologic Disorders.

• Analgesia (e.g., meloxicam at 0.3 mg/kg PO s.i.d.) can be given for many weeks.

• Where possible, wean the animal onto a diet high in long fiber (i.e., grass and hay), as this encourages normal chewing and dental wear on the back teeth. Provision of a pumice stone may encourage gnawing behavior.

• Note: Many chinchillas with dental disease have adrenal hyperplasia (Crossley 2001). See Endocrine Disorders.

• Fractured incisors

• Burr and file back to both the affected tooth and the contralateral to allow normal even wear to occur.

Gastrointestinal tract disorders

It is normal for guinea pigs, chinchillas, and degus to coprophage, especially at night (Kenagy et al 1999).

Disorders of the oral cavity

• Dental disease (see Dental Disorders)

• Foreign bodies, especially cheek impactions or under tongue

• Choking (see Respiratory Disorders)

• Parotid salivary gland abscessation

• Investigation requires sedation or anesthesia for thorough examination of the oral cavity.

• Foreign bodies and choking require removal of the problem material.

• Parotid salivary gland abscessation requires surgical resection of the abscess; consider bacteriologic culture and sensitivity from the abscess.

• Cheilitis (crusty lesions at corner of mouth in guinea pigs)

• Hypovitaminosis C (see Nutritional Disorders)

• Secondary bacterial/fungal infection—classically Staphylococcus cheilitis

• Poxvirus

• Chewing on sharp foods or cage mesh

Differential diagnoses for gastrointestinal disorders

Viral

• Coronavirus (guinea pigs)

Bacterial

• Clostridium difficile

• C. perfringens Type E (guinea pigs)

• C. perfringens Type D and occasionally Type A (chinchillas)

• C. piliforme (Tyzzer disease)

• Escherichia coli

• Listeria monocytogenes (can be asymptomatic in chinchillas, but also has visceral and neurologic presentations—see Neurologic Disorders)

• Campylobacter spp. (asymptomatic)

• Citrobacter freundii

• Yersinia pseudotuberculosis

• Salmonella spp.

• Corynebacterium spp.

Fungal

• Torulopsis pintolopesii

Protozoal

• Guinea pig

• Eimeria caviae

• Eimeria spp. (cross-infection with rabbit Coccidia)

• Cryptosporidium muris and C. wrairi

• Entamoeba caviae

• Tritrichomonas caviae

• Giardia caviae

• Balantidium caviae

• Chinchilla

• Giardia

• Trichomonas (hemorrhagic typhilitis)

• Balantidium (hemorrhagic colitis)

• Cryptosporidium

• Eimeria chinchillae

Parasitic

• Guinea pig

• Paraspidodera uncinata (Heterakidae nematode)

• Cestodes (from wild rodents)

- Fasciola hepatica

- Fasciola gigantica

• Chinchilla

• Physaloptera

• Hymenolepis spp.

• Haemonchus contortus

Nutritional

• Sudden influx of greens or fruit in diet, probably a carbohydrate overload and fermentation producing gastric dilatation, dysbiosis

• Hypovitaminosis C in guinea pigs (malabsorption, pyogranulomatous enteritis—see Nutritional Disorders)

• Constipation (degus and chinchillas on poor diet, possibly too low in short-length fiber)

Neoplasia

Other noninfectious problems

• Iatrogenic dysbiosis (e.g., from antibiotics, especially penicillin, procaine, erythromycin, lincomycin, clindamycin, streptomycin, erythromycin, aureomycin, bacitracin, and spiramycin). Such dysbiosis can result in clostridial overgrowth.

• Intestinal obstruction

• Neoplasia, foreign body, abscess, impaction

• Colorectal impaction (guinea pigs)

• Cecal impaction

• Cecal dilatation/tympany

• Rectal prolapse

• Gastric ulceration (chinchillas)

• Gastric torsion

• Gastric dilatation

• Aerophagy during anesthetic induction and recovery

• Pregnant, unfasted females especially at risk of dilation/torsion

• Sudden influx of greens in diet (probably carbohydrate overload and fermentation)

Findings on clinical examination

• History of poor diet (e.g., excessive fruit or greens—diarrhea, dysbiosis; coarse or moldy feeds—gastric ulceration)

• Diarrhea

• Watery diarrhea (C. piliforme, hypovitaminosis C)

• Decreased fecal output

• Constipation

• Gut stasis

• Colorectal impaction

• Obstruction

• Foreign body

• Cecal impaction

• Frank blood in feces (severe enteritis)

• Occult blood in feces (hypovitaminosis C)

• Depression

• Hypothermia

• Gut stasis; gastric bloat

• Weight loss

• Impacted rectum; may find inspissated feces, wood shavings, trichobezoars (guinea pigs)

• Flaccid hind-limb paralysis

• Subcutaneous inguinal edema (C. piliforme in guinea pigs)

• Dyspnea (compression of thoracic cavity with gastric dilatation, gastric torsion, cecal dilatation)

• Death

Investigations

1. Radiography

a. Trichobezoars and cecal impactions likely linked to either foreign bodies or poor gut motility

b. Assess lumbar spine for lesions in cases of colorectal impaction.

2. Routine hematology and biochemistry

3. Serology for C. piliforme, coronavirus

4. Culture and sensitivity

5. Fecal examination

a. Light microscopy (parasites)

b. Gram stain

c. Normal gastrointestinal flora is gram positive (i.e., Bifidobacterium spp., Bacteroides spp., Eubacterium spp., and Lactobacillus spp.)

d. Giemsa or acid-fast staining (Cryptosporidium)

6. Cytology

7. Electron microscopy

8. Endoscopy

a. Gastroscopy, colonoscopy

b. Endoscopic laparoscopy

9. Ultrasonography

10. Biopsy

Management

1. Fluid therapy (see Nursing Care)

2. High-fiber diet

3. May need to syringe feed

4. Probiotics. These may be of benefit, but often species specific. One study found no benefit in administering oral Lactobacillus spp. as an aid to antibiotic-induced enteritis in guinea pigs (Wasson et al 2000).

5. Transfaunation using caecotrophs from a healthy rodent may help natural gut flora to reestablish.

6. Only use antibiotics if indicated. Many cases do not require their use, which can be counterproductive.

7. Analgesics can be necessary, but avoid those likely to exacerbate gastrointestinal tract ulceration (e.g., flunixin).

TreatmentZspecific therapy

• Clostridial overgrowth and Tyzzer disease

• Covering antibiotics, especially cephalosporins, metronidazole (20 mg/kg PO s.i.d.), and vancomycin (20 mg/kg PO s.i.d.) plus:

- Cholestyramine at 100 mg/mL in drinking water

- Vaccination with clostridial toxoids to reduce mortalities (chinchillas)

• Corona virus:

• Supportive care only

• Torulopsis pintolopesii

• Nystatin at 100,000 units/kg PO b.i.d.

• Eimeria spp.

• Sulfonamides (e.g., co-trimoxazole at 30 mg/kg PO b.i.d.)

• Giardia

• Metronidazole 20 mg/kg PO s.i.d.

• Cryptosporidium

• Potentiated sulfonamides may be of use

• Nitazoxanide (Alinia) may prove useful

• Nematodes

• Paraspidodera uncinata: Fenbendazole 20 mg/kg PO s.i.d. for 5 days

• Cestodes and trematodes

• Praziquantel 5 to 10 mg/kg PO, SC, or IM. Repeat after 10 days.

• Simple constipation

• Offer liquid paraffin or syrup of figs.

• Increase fiber in diet.

• Consider other etiologies.

• Trichobezoars and cecal impactions

• Note: These can be symptomatic of foreign body, gut motility problem, or dehydration.

• Aggressive fluid therapy

• Analgesia

• Gut motility modifiers (e.g., metoclopramide at 0.2 to 1.0 mg/kg SC, PO t.i.d. and cisapride at 0.5 to 1.0 mg/kg PO s.i.d. or b.i.d.)

• Avoid surgery unless absolutely necessary.

• Colorectal impactions

• Frequent removal of impacted feces

• Supplement with B vitamins and vitamin K as caecotrophy will be compromised.

• Rectal prolapse

• Give fluids and covering antibiosis.

• Moisten, lubricate, and replace.

• Keep in place with purse-string suture.

• May require resection of devitalized area and anastomosis of cut ends

• Withhold high-fiber foods for a few days.

• Gastric dilatation

• Tympany: Consider gut motility enhancers such as metoclopramide at 0.5 mg/kg SC or PO every 6 to 8 hours, offering or syringe feeding a high-fiber diet (e.g., Science Recovery Diet or Oxbow Critical Care). Decompress by stomach tube or by paracentesis if severe.

• Torsion: Can twist >540 degrees; immediate decompression by stomach tube or paracentesis but transabdominal decompression highly likely to initiate a peritonitis. Early surgical correction to decompress; retorsion and gastric fixation are likely to give best results.

• Fluid therapy

• Feed high-fiber, low-carbohydrate foods.

• Cimetidine at 5 to 10 mg/kg PO, SC, or IM every 6 to 12 hours

• Probiotics (see Management)

• Gut stasis, gastric dilation accompanied by hind-limb paralysis in lactating chinchillas often the result of hypocalcemia; usually seen in lactating chinchillas at 2 to 3 weeks postpartum. Calcium gluconate IV or IP at 94 to 140 mg/kg (see Systemic Disorders)

• Gastric ulceration

• Cimetidine at 5 to 10 mg/kg PO, SC, or IM every 6 to 12 hours

• Intestinal obstruction

• Fluid therapy

• Covering antibiosis

• Enemas using warm soapy water

• Surgical correction/removal of foreign body.

Nutritional disorders

• Hypovitaminosis A (chinchillas—see Ophthalmic Disorders)

• Hypovitaminosis C (scurvy—guinea pigs, not proven but often suggested for degus)

• Hypervitaminosis C (may cause heterotrophic bony metaplasia and calcification (metastatic calcification in guinea pigs)

• Hypovitaminosis E (nutritional muscular dystrophy—see Musculoskeletal Disorders)

• Hypovitaminosis E or choline or methionine deficiency linked with yellow discoloration of pinna and raised, pigmented lesions in the perineal area and ventral abdomen in chinchillas

• Thiamine deficiency (chinchillas)

• Fatty acid deficiency (chinchillas)

• Pantothenic acid deficiency

• “Cotton fur” (chinchillas)

• Nutritional metabolic bone disease (chinchillas)

• Hepatic lipidosis (see Hepatic Disorders)

Findings on clinical examination

• Vague ill health, including weight loss and dehydration

• Dental disease (hypovitaminosis C in guinea pigs)

• Motor abnormalities, including trembling, paralysis, and convulsions

• Pain

• Spontaneous fractures (hypovitaminosis C in guinea pigs)

• Ocular and nasal discharges

• Abortions and stillbirths

• Soft stools/diarrhea (hypovitaminosis C in guinea pigs)

• Spontaneous hemorrhage (hypovitaminosis C in guinea pigs)

• History of guinea pig fed on rabbit food (hypovitaminosis C in guinea pigs)

• Coat abnormalities (cotton-like appearance of fur—cotton fur—and hypovitaminosis A in chinchillas)

• Alopecia (chinchillas—fatty acid deficiency, pantothenic acid deficiency)

• Polydipsia (hepatic lipidosis)

• Edema (hypovitaminosis C, hepatopathy, cardiovascular disease)

Investigations

1. Radiography

a. Enlarged joints and costochondral junctions, epiphyseal and long bone malformations, pathological fractures (hypovitaminosis C)

b. Dental abnormalities (hypovitaminosis C—see also Dental Disorders)

2. Routine hematology and biochemistry

a. Anemia

b. Clotting disorders

3. Culture and sensitivity

4. Cytology

5. Endoscopy

6. Ultrasonography

7. Biopsy

TreatmentZspecific therapy

• Hypovitaminosis C

• Supplement with vitamin C (ascorbic acid) at 50 to 100 mg/kg PO daily.

• Feed with commercial guinea pig food supplemented with vitamin C. Maintenance requirements are 10 mg/kg for adults and 30 mg/kg during pregnancy (Huerkamp et al 1996).

• Rabbit food fed to rabbit/guinea pig combinations is likely to induce hypovitaminosis in the guinea pig.

• Guinea pig food that is out of date or has been poorly stored is likely to contain insufficient levels of vitamin C.

• Degus should be fed either a dedicated degu diet or a vitamin C-supplemented guinea pig food.

• Cotton fur: Excessive protein intake. Alter rations to lower protein (15%) diet.

• Fatty acid deficiency

• Supplement with unsaturated fatty acids, especially linoleic and arachidonic acid.

• Recommend feeding 5 to 10 mg/kg evening primrose oil (Richardson 2003).

• Monitor food storage facilities to prevent rancidity.

• Pantothenic acid deficiency (may be complicated by zinc deficiency)

• Supplement with dietary pantothenic acid and zinc.

• Nutritional metabolic bone disease

• Calcium gluconate IM at 94 to 140 mg/kg IV or IP

• Investigate and correct calcium/phosphorus imbalance in diet.

Hepatic disorders

Bacterial

• Hepatitis

• Yersiniosis (see Systemic Disorders)

Fungal

• Ingestion of aflatoxins and mycotoxins in food

• Histoplasmosis (see Systemic Disorders)

Protozoal

• Cryptosporidium (chinchillas—see Gastrointestinal Tract Disorders)

Parasitic

Nutritional

• Hepatic lipidosis (especially degus)

Neoplasia

• Lymphosarcoma

• Other hepatic and biliary tumors

Other noninfectious problems

• Amyloidosis (secondary to chronic infection, especially pododermatitis in guinea pigs)

Findings on clinical examination

• Diarrhea

• Weight loss

• Jaundice

• Polydipsia/polyuria

• Poor blood clotting (hepatic lipidosis)

• Hepatomegaly

Investigations

1. Radiography

a. Routine hematology and biochemistry

b. Liver parameters raised

c. Hyperlipidemia (hepatic lipidosis)

d. Anemia

e. Ketones in blood

2. Urinalysis

a. Ketonuria (hepatic lipidosis)

3. Culture and sensitivity

4. Cytology

5. Endoscopy

6. Ultrasonography

a. Hepatomegaly (hepatic lipidosis)

7. Biopsy

Management

1. Fluid therapy

2. Milk thistle (Silybum marianum) is hepatoprotectant; dose at 4 to 15 mg/kg PO b.i.d. or t.i.d.

3. Lactulose at 0.5 mL/kg PO b.i.d.

TreatmentZspecific therapy

• Hepatic lipidosis

• Aggressive fluid therapy

• Parenteral nutrition with glucose and vitamins

• Assisted feeding by syringe. Calcium gluconate PO or propylene glycol PO may be of use.

• Dexamethasone at 0.1 to 0.6 mg/kg IM

• Mycotoxicosis

• General management of liver disease

• Prevent exposure to sources of contamination, usually old foods with fungal contamination

• Neoplasia

• Lymphosarcoma (see Cardiovascular and Hematologic Disorders)

• Hepatic neoplasia

• Poor prognosis. In some cases surgery may be possible, but euthanasia is more practicable.

Pancreatic disorders

Nutritional

• Congenital manganese deficiency (diabetes mellitus)

Neoplasia

• Islet tumors (benign)

Other noninfectious problems

• Amyloidosis (secondary to chronic infection, especially pododermatitis in guinea pigs)

• Diabetes mellitus (especially degus)

Findings on clinical examination

• Weight loss

• Polydipsia/polyuria

• Bilateral cataracts

• Infertility and other reproductive abnormalities

• Cystitis

Investigations

1. Radiography

2. Routine hematology and biochemistry

a. Hyperlipidemia

b. Hyperglycemia (Table 3-5)

c. Fructosamine (guinea pigs: 134 to 271 pmol/L)

3. Glucose tolerance test

Glucose tolerance test for guinea pigs

1. Keep on an 18-hour fast.

2. Take baseline blood glucose sample.

3. Give oral glucose 1.75 g/kg.

4. Repeat blood glucose after 4 hours.

5. Normal blood glucose bgcolor=white>110-160 131 ± 13 Pulmonary artery peak flow velocity (m/s) 0.37-1.00 0.61 ± 0.16 0.53-1.47 0.97 ± 0.32 Pulmonary artery ejection time (ms) 125-225 192 ± 34 105-150 129 ± 12 Mitral valve inflow summated (m/s) — — 0.50-0.90 0.74 ± 0.10 Mitral valve, E-wave peak flow velocity (m/s) 0.35-0.60 0.48 ± 0.08 — — Mitral valve, A-wave peak flow velocity (m/s) 0.17-0.40 0.29 ± 0.07 — —