Parrots and related species
Members of the parrot family are the most common avian pet and, therefore, the most likely to be presented to the veterinarian. Table 8-1 shows the most commonly encountered species.
Consultation and handling
Psychologically, most pet birds are little different from their wild ancestors—the veterinary surgeon constitutes a potential predator, so the bird is likely to exhibit a flight or fight response when handled. Exceptions to this are hand-reared parrots (or imprinted raptors and owls). However, in extremis, birds vary in their susceptibility to stress, and while some, such as the larger psittacines, can be handled relatively safely, others, such as canaries, carry a greater risk.
A great many captive-bred, hand-reared birds can be superficially examined while perched on the owner or on a freestanding perch, thereby minimizing stress. If care and patience are used, then auscultation of the lungs and air sacs, plus some assessment of body condition, can be achieved in this way.
It is important to weigh parrots at every consultation (Fig. 8-1); tame birds can be accurately weighed using a small perch designed to fit onto standard weighing scales.
Aggressive birds, or birds unused to handling, may need to be “toweled” in order to examine them. Use a large towel that will cover most of the bird. Drop or place it over the bird such that the head is covered and the bird cannot see your hands. With one hand, grab the bird's head or neck from behind so that there is control of the beak, and use the other hand to gather up the rest of the bird into the towel. Do not in any way compress the sternum, as this will seriously compromise the bird's breathing.
Birds will attempt to mask signs of illness and so may not exhibit clinical signs until a disease course is quite advanced. It is important to observe the bird from a distance for several minutes prior to handling, as a relaxed bird is more likely to show signs of ill health.
Important nonspecific clinical signs in parrots
• Heavy lidded/dark periorbital coloring
• Fluffed up/feather plucking
• Abnormal or absent feeding/drinking behavior
• Polydipsia/polyuria
• Lethargy
• Abnormal activity
• Change from normal perching activity or on floor of cage
• Abnormal profile
• Abnormal breathing action
• Abnormal vocalization
• Tail-bobbing. A sign of dyspnea. Respiratory rates of psittacines are high, but a recovery time exceeding 3 min would be considered abnormal.
• Regurgitation
From Malley (1996).
259
| Table 8-1 | ¾rrots and related species: Key facts | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| African grey parrot | Blue-fronted Amazon parrot | Blue and gold macaw | Moluccan cockatoo | Peach-faced lovebird | Cockatiel | Budgerigar | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Average life span (years) | 50-70 | 40-50+ | 50-80+ | 50+ | 10+ | 10-20+ | 4-13 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Weight (g) | 300-400 | 320-460 | 950-1175 | 640-1025 | 50-61 | 80-90 | 45-50 (60+ for large show budgerigars) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Sexing | DNA or surgical sexing | DNA or surgical sexing | DNA or surgical sexing | DNA or surgical sexing. Also males have black irides, females have reddish brown. | DNA sexing | The small, ventral (true) tail feathers (not the overlying longer remiges) are barred in females (hard to assess in Lutinos). The red-orange color of the cheek patches is more pronounced in males. | Cere is blue and smooth in males; brown and rough in females. Young blue mutation females may have a pastel-blue cere. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Estimating age | Young chamber such as an incubator, and supply oxygen as close to the bird's head as possible. 3. Allow the bird a few minutes to relax in this warm, high-oxygen environment before continuing with the examination. 4. If it is imperative to handle the bird, warn the owner first that although you must do this, there is a chance of losing the bird. If necessary ask the owner to sign a consent form. 5. Handle the bird either with your hands or with a towel. Never use gloves or gauntlets. With larger psittacines, if necessary, have an assistant grip the head firmly from behind if you are concerned about being bitten. Do not grip around or otherwise compress the sternum as this will compromise respiration. 6. Consider either sedation or inducing anesthesia by masking the bird down with isoflurane or sevoflurane for a more detailed examination. For those birds with respiratory or cardiovascular compromise, the relative risks and benefits of anesthesia need to be considered.
Avian core body temperature often exceeds 40.5° C, and birds have a large surface area relative to body mass, which means that they must expend a great deal of energy in thermal homeostasis. Feathers act as an insulative layer but do not grow back as readily as mammalian fur, so as few as possible should be removed, should surgery be indicated. Heat loss and, therefore, energy conservation can be reduced by placing the bird close to a heat source—vivarium heat mats are ideal for this. Place a towel or similar over the mat to prevent burns and protect the mat from fluids. Young chicks are unable to thermoregulate, so they must be maintained in an incubator. Fluid therapy Birds are primarily uricotelic which, as in reptiles, predisposes them to gout-related problems. Blood volume is between 4.4 and 8.3 mL/100 g body weight in chickens. In some species, it can be as high as 14 mL/100 g. Dehydration 1. Most critically ill birds should be assumed to be 5% to 10% dehydrated. 2. Increased skin turgor over the foot or upper eyelid, collapse or poor filling of the ulnar vein, sunken or glazed eyes, dry and tacky mucous membranes, tachycardia, depression, and red or wrinkled skin in psittacine neonates all indicate dehydration. 3. The daily maintenance water requirement for psittacine birds is around 50 mL/kg per day, with that of passerines and young birds being much higher. 4. A 500-g (0.5-kg) bird with 10% (0.1) dehydration, therefore, requires (0.5 ? 0.1) liters = 0.05 L = 50 mL fluid. As in other species, which fluids are given depends on the reason for giving fluids. Half of the fluid deficit should be replaced within the first 12 to 24 hours. The remaining 50% is divided over the following 48 hours, to be given alongside the daily maintenance. Fluid administration • Per cloaca. Water can be absorbed from the cloaca (and naturally from material refluxed into the colon), so this can be used as route for rehydrating with small volumes when there is a risk of aspiration pneumonia (Table 8-2). • Oral fluids are usually given by crop tube. Not suitable for birds that are regurgitating, recumbent, or fitting. • Intravenous. Birds can tolerate fluid replacement rates of up to 10 mL/kg given in a bolus, if given slowly over 5 to 7 minutes. Sites include the right jugular vein, brachial vein (Fig. 8-2), and the medial metatarsal vein. Intravenous catheters are difficult to maintain in birds, so bolus administration is preferred. Isotonic solutions should be administered slowly at a rate of 10 to 15 mL/kg. A “shock” dose of 90 mL/kg can be used if large volumes are needed rapidly. Suggested individual bolus volumes are listed in Table 8-3.
Fig. 8-2. Placement of an intravenous catheter into the brachial vein of a cockatoo. Use a collar if it is to be kept in place for several days. • Subcutaneous fluids can be given into the interscapular area (not caudal neck to avoid the cervicocephalic air sac) or the inguinal region. Small volumes (5 to 10 mL/kg) should be given at each site, and absorption may be poor. • Intraosseous. Distal ulna and proximal tibiotarsus. Strict asepsis and anesthesia. All types of fluids, including blood transfusions. Do not administer very acidic, alkaline, or hypertonic solutions IO without diluting them first. Choice of parenteral fluids • Crystalloids. Only 25% of a crystalloid solution remains in the peripheral vasculature 30 minutes after administration. Hartmann’s solution contains lactate that is converted to bicarbonate by the liver and so may help correct acidosis but is contraindicated with hypernatremia. • Hypertonic saline solution at 3% to 7.5% will help to correct circulatory collapse by triggering fluid shifts from the interstitial space into the circulation, followed quickly by isotonic solutions to prevent tissue dehydration. Do not use hypertonic solutions if cranial hemorrhages are suspected. • Colloids. Bolus administration of hetastarch at 10 to 15 mL/kg IV t.i.d. for up to 4 treatments may be safe and effective for hypoproteinemia. • Oxyglobin can be given at a dose rate of up to 15 mLzkg IV or IO. • Whole blood. Birds are tolerant of anemia, but a transfusion should be considered if the PCV falls below 15.0 L/L. Use blood from the same or similar species; blood groups have been only poorly investigated. Nutritional supplementation If the bird is eating normally, then supply its usual diet. For short-term management, recovery diets commercially available for dogs and cats (nonmilk-based) may be crop-tubed for carnivorous, insectivorous, or omnivorous birds. Dextrose can be given orally, by subcutaneous injection up to 2.5%, or IV. It is a metabolic acidifying agent and may be contraindicated in cases of metabolic acidosis. Note that most birds are diurnal and will not feed in the dark. For parrots, hand-rearing formula can be used. Wing clipping of pet parrots A badly clipped bird is not only at increased risk of damage to itself, but such clipping may also predispose to feather-picking and self-mutilation. Wing clipping can be controversial, but the major justification for wing clipping is that it facilitates the necessary interaction between a pet parrot and the other family members, allowing the bird to become involved with, and behave as, part of the family (or “flock”) rather than being confined to its cage. However, the ideal would be that the bird is left fully flighted and controlled verbally, using commands such as “step up,” “step down,” “leave,” and “no.” Wing clipping 1. Both wings should be clipped, allowing the bird to maintain its balance. 2. It is the primary flight feathers that allow lift, and it is these that should be trimmed such that the cut end is tucked beneath the coverts. 3. Developing “pin” feathers should not be cut as these will hemorrhage; instead leave alone and leave a feather alongside it or on either side for support to prevent accidental damage. Microchipping 1. Microchips are placed into the left pectoral musculature.
2. Occasionally hemorrhage may occur, but usually digital pressure is sufficient for hemostasis. 3. Microchips inserted SC, although potentially less traumatic, are readily palpable and are subject to removal and fraud. Analgesia
Sedation • Midazolam 0.5 to 3.0 mg/kg IM or intranasal • Diazepam 0.2 to 2.0 mg/kg intranasal. IM administration likely to be irritant with delayed absorption (Mans 2014) • Butorphanol 1.0 to 3.0 mg/kg IM or intranasal • Midazolam 1 to 2 mg/kg plus butorphanol 1 to 2 mg/kg IM if heavier sedation is required. Macaws usually require this combination to gain adequate sedation for clinical procedures (Mans 2014). • Benzodiazepines can be reversed by flumazenil at 0.01 to 0.1 mg/kg PO. Anesthesia From a practical point of view, induction and maintenance with gaseous anesthesia are of choice. Atropine can be given as premedication at 0.05 to 0.1 mg/kg SC. This reduces mucus and counters bradycardia from vagal stimulation during surgery. Gaseous anesthetic protocol 1. Hold the bird's head into a mask or place into an induction chamber. Isoflurane offers a rapid induction and recovery (as does sevoflurane). 2. Intubate (uncuffed endotracheal tube) whenever possible. 3. During anesthesia, regularly give positive-pressure ventilation to reduce risk of CO2 buildup in the abdominal air sacs. 4. Main sources of heat loss are the extremities (especially the feet) and the air sacs. Wrap the feet with silver foil and maintain the bird on an external heat source. 5. If using halothane, start at low concentrations (0.5% to 1.0%) and gradually increase to 3.0% to 4.0%. Induction at high concentrations can lead to dangerously high levels of halothane present in posterior air sacs. Attempts to resuscitate bird by flushing through with oxygen or manual ventilation will only force this reservoir of halothane through the lungs, further increasing blood concentrations. Parenteral anesthesia 1. Always weigh the bird accurately before using parenteral anesthesia, and always intubate and maintain on oxygen whenever possible. 2. A range of anesthetic protocols are available from the literature. The ones the author has used include: a. Ketamine at 5 to 30 mg/kg IV or IM. No analgesic effect. Avoid birds with potential liver/kidney complications. b. Ketamine 5 mg/kg plus xylazine 0.25 to 1.0 mg/kg IV or IM c. Ketamine 5 to 20 mg/kg plus midazolam 0.25 mg/kg IV or IM. This gives good sedation, muscle relaxation, and recovery. d. Ketamine 3 to 6 mg/kg plus medetomidine 25-100 gg/kg IV or IM e. Both medetomidine and xylazine can be reversed with atipamezole at 5 ? medetomidine dose. Air sac perfusion anesthesia Avian respiratory anatomy means that the trachea can be “bypassed” by insertion of a suitable cannula into one of the caudal air sacs (abdominal or caudal thoracic) for delivery of oxygen and anesthetic gases. This technique is suitable for oral or tracheal obstructions or if surgery is required at or around the oral cavity. Glottal or tracheal foreign bodies or other obstructions will usually give their presence away by producing a whistling sound during the respiratory cycle. These birds are extremely liable to sudden death. The main priority is to establish a patent airway as quickly as possible, therefore the need to anesthetize and insert an air sac tube. Air sac perfusion anesthesia technique 1. Use soft tube with holes in walls. 2. Use a 4-mm-diameter tube for a 350-g bird, increasing pro rata. 3. A left lateral approach is used with the left leg extended cranially and a small incision made behind the last rib and ventral to the flexor cruis medialis muscle (Fig. 8-3). 4. A small pair of hemostats can then be used to enter the coelom in a craniomedial direction, which will provide access to the caudal thoracic air sac. 5. A tube is then secured in place with a suture and attached to the anesthetic machine. Note: A higher airflow rate (>50% above normal) will be required to maintain anesthesia this way. 6. The tube can be left in situ for 1 to 3 weeks.
Fig. 8-3. Anatomical markers for the placement of an air sac tube. Recovery • Keep quiet. • Wrap wings gently in towel/paper toweling to reduce injury from flapping. • Keep warm, preferably mid-20s° C.
• Recovery must be fast from anesthetic—birds under 100 g should be eating within 30 minutes. Cardiopulmonary resuscitation 1. Can use doxapram at 5 to 7 mg/kg IM or sublingually. 2. Intubate if not already done. 3. Intermittent positive-pressure ventilation once every 5 seconds. 4. If in cardiac arrest, begin rapid chest compressions. 5. Give epinephrine at 0.5 to 1.0 mL/kg of 1:1000 intrathecal, intracardiac, IO, or intraperitoneal. Skin disorders Avian skin is very thin, with the epidermis only up to 10 cells thick in feathered areas. There are few cutaneous glands: 1. Uropygial gland. Not present in all species (e.g., Amazon parrots and Pionus parrots). When present, it lies dorsally near the tip of the tail. There can be up to 18 orifices depending on the species. Usually bare except for a tuft of down feathers known as uropygial wick. Secretes a lipoid sebaceous secretion—sebum—that is water repellent. It also helps to keep plumage supple and smooth, contains vitamin D3 precursors, has antibacterial and antifungal properties, and enhances feather coloration. However, most sebum is produced from epidermal cells that contain keratin-bound phospholipids that coat the skin and feathers. 2. Small wax-secreting glands are present in the external wall of the auditory meatus. 3. There are mucus-secreting vent glands. 4. There are no sweat glands. Commensal bacterial numbers on the skin of birds are considered to be lower than those found on mammals. Yeasts are infrequent commensals. Malassezia is not isolated from normal or self-mutilating birds (Preziosi et al 2006); in the same study, Candida albicans was isolated but significance was unclear. Feathers serve a number of functions, including insulation, protection from trauma, accessories to flight, species recognition patterns, and display. There are several types and subgroups of feathers. Feather types 1. Contour feathers are divided into: a. Flight feathers i. Remiges (carried on the wing) (1) Primary—borne on the manus (2) Secondary—borne on the antibrachium ii. Retrices (carried on the tail) b. Body feathers c. Coverts—cover the bases of the retrices or remiges d. Ear coverts—screen the external opening of the ear and improve hearing 2. Other feathers include down feathers, filoplumes, bristles, and semi-plumes. Various intermediate forms of feathers will be encountered. Powder feathers usually structured like down feathers, occasionally semi-plumes, and contours shed a fine white powder of keratin onto contour feathers to provide waterproofing. Particularly obvious in African grey parrots and cockatoos. Signs of skin disease Pruritus • Flies • Hippoboscids (flat flies/louse flies) occasionally encountered, especially with aviary birds. Can transmit hemoparasites such as Haemoproteus and Leukocytozoon, as well as transferring mites and lice among individuals. • Lice: Can reach significant numbers on debilitated birds • Ticks: Occasionally on new imports. Sudden death associated with tick attachment to head. Suggested etiologies include hypersensitivity reactions, toxin injection, or a tickborne infection. Can also transmit other diseases such as haemoprotozoan parasites, Borrelia spp., and louping ill • Red mite (Dermanyssus avium) and other species • Northern fowl mite (Ornithonyssus spp.) • Feather mites: Found between the barbs on the ventral surfaces of feathers. Often niche specific so in the budgerigar, Protolichus lunula is found on the wing and tail feathers, whereas Dubininia melopsittaci occurs on the smaller body feathers. • Quill mites: Live inside quills • Sarcoptid mites present on the feather shafts may be encountered occasionally. Treat as above. • Quill wall mites • Skin mites • Epidermoptid mites • Knemidocoptid mites. Common is Knemidocoptes pilae (scaly face/scaly leg) • Harpirhynchid mites: Attach to feather bases. May induce hyperkeratotic epidermal cysts • Cheyletiellid mites: Rare • Polyfolliculitis: Common in lovebirds. Multiple feathers arise from single feather follicle.
Fig. 8-4. Stress lines in the primary and secondary flight feathers in an African grey parrot. Note also the abnormal red pigmentation.
Ulceration/folliculitis • Erysipelas • Staphylococcus • Aspergillus Feather damage, pathology, and loss • “Stress” lines (see “Findings on Clinical Examination” below and Fig. 8-4) • Dystrophic feathers sometimes occur secondary to folliculitis. • Polyomavirus (papovavirus): Usually presents in chicks but is carried asymptomatically by adults. Signs include a distended abdomen, lack of or malformed down feathers, multifocal follicular and feather pulp hemorrhages, and retarded growth of tail and contour feathers (infected budgie chicks may be referred to as “walkers”). There may be a urate-soaked vent because the virus also infects the liver and the kidneys. Also slow weight gain, slow emptying crop, and vomiting. This virus is responsible for budgerigar fledgling disease, which usually is rapidly fatal. • Psittacine beak and feather disease (PBFD, circovirus; Fig. 8-5). Usually affects birds younger than age 3 years. Signs include loss of feathers, decrease in down feathers on flanks, retained pin feathers, short clubbed feathers, and deformed feathers. Beak may change in color, grow abnormally, and become necrotic, beginning with a palatine crust in the maxillary beak. Secondary bacterial infections make the condition worse. Older, chronically infected African grey parrots may produce red feathers in abnormal position such as the covert feathers (Fig. 8-6). Diet • In macaws especially, thinning of the feathers and retention of keratin sheaths of pin feathers, in particular the flight and tail feathers, is linked to poor diet.
Fig. 8-5. Psittacine beak and feather disease in a sulfur-crested cockatoo. • Unsupplemented seed diets are deficient in minerals, sulfurous amino acids, and vitamins; birds on unsupplemented diets show increased feather replacement intervals (Wolf et al 2003) and may exhibit old, tattered feathers. Self-trauma • Secondary to ectoparasites • Hand-reared parrots may never learn the normal species-specific methods of preening. • Grossly abnormal feathers in budgerigars—called feather dusters or chrysanthemum disease—are a genetically recessive condition. • Chewing at extremities; can be secondary to topical irritations Scaling and crusting • Papillomavirus: Reported in Timneh African grey parrots. Proliferative cutaneous lesions seen on head, especially eyelids, beak commissure, and skin contiguous with lower beak • Herpesvirus: Described in cockatoos and macaws as dry proliferative lesions on the toes that are limited to extremities; not life-threatening • Hyperkeratosis of the plantar surfaces of the feet—hypovitaminosis A (see Nutritional Disorders) Erosions and ulceration • Neoplasia (squamous cell carcinoma; Klaphake et al 2006)
Fig. 8-6. Abnormal red pigmentation in an African grey parrot with psittacine beak and feather disease. Nodules and nonhealing wounds • Avian pox virus (skin pox) • Wartlike lesions of the skin. Yellowish nodules form on the beak, eyelids, and other areas of the skin that disintegrate and discharge a serosanguineous fluid. The areas then scab over. When present on the feet, lesions may occlude distal vasculature, resulting in tissue necrosis of the lower extremities. Note: Can occur in a diphtheritic form or a septicemic form. • Staphylococcus may occasionally be encountered as a cause of dermatitis. More often it is isolated as a secondary invader in bumblefoot. • Candidiasis has been seen as focal raised lesions as well as more generalized ulcerations. Head lesions have been reported in eclectus parrots, Amazon parrots, and cockatiels. Aspergillus lesions, Trichosporon asahii, and dermatophytosis are occasionally encountered. • Feather cysts: Secondary to follicle damage; the developing feather is unable to emerge and forms a large, cystlike structure. • Cryptococcosis (Berrocal 2004) • Mycobacteria (Ferrer et al 1997) • Bumblefoot: Typically chronic infection and abscessation of the feet, especially the plantar surfaces. Often due to staphylococci or streptococci. Changes in pigmentation • Erysipelothrix infections may cause an erythema of the skin in an acute infection with sudden death.
Fig. 8-7. Prepatagial chronic ulcerative dermatitis in an African grey parrot. Chronic ulcerative dermatitis (CUD) • Usually associated with chronic conditions such as mycobacteriosis, tumors, abscesses, or xanthomas. Poor nutrition may also contribute. Four main presentations are: • Prepatagial CUD: Wing web area. Possibly linked to Giardia or hypovitaminosis E. Usually very pruritic and painful. Patagium may also be affected. Commonly seen in chronic self-mutilating African greys (Fig. 8-7) • Proventer CUD: Keel area; common in African greys and large Amazons. Secondary to trauma following hard landings. Bruises or splits forming ulcers. • Postventer CUD: Between cloaca and tail. Possibly similar etiology to proventer CUD. Poor nutrition also implicated • Squamous cell carcinoma (Klaphake et al 2006) • Ectoparasites (see “Pruritus” above) Alopecia • Pruritic (self-mutilation) versus nonpruritic. PBFD is provisionally differentiated from self-inflicted trauma in single birds as feathers on head also affected; normally bird cannot reach these to self-damage. Neoplasia • Lipomas (Fig. 8-8), fibrosarcomas, liposarcomas, and squamous cell carcinomas are some of the more common skin neoplasms reported in birds. Xanthomas are common, especially in budgerigars. These are nonneoplastic yellowish nodules or plaques caused
Fig. 8-8. Lipoma in a budgerigar.
by an accumulation of cholesterol and fats. Can be ulcerative. Often found over an area of pathology such as a lipoma. Allergies • There is a strong suggestion that allergies may be the cause of skin disease in some cases, especially in Old World psittacines. Findings on clinical examination • Observe bird in cage or at rest on owner. Assess if it show signs of a typical sick bird—ruffled, fluffed up feathers, sleepiness, and tail “pumping.” Is it pruritic? • Assess the surroundings. Are feces normal? Stress or sudden influx of fruit may trigger very loose feces. • Handle the bird: • Examine nares, beak, eyes, and buccal cavity, including choana. Look particularly for signs of vitamin A deficiency (see Nutritional Disorders). • Examine skin; note signs of inflammation, hyperkeratosis, ulceration, and trauma. • Assess feather quality: • Stress lines—lines visible on the vanes of the feather that denote areas of poor quality of the barbs. Thought to be linked to release of endogenous corticosteroid.
Fig. 8-9. Anesthesia of a cockatoo for further skin investigation. • Frayed, dirty, or matted feathers: Inappropriate size caging may cause repeated damaged to the retrices of those birds with long tails such as parakeets and macaws. • Abnormal feather coloration may result from nutritional deficiencies, hepatopathies, or PBFD. • Examine for parasites: • Pluck one or two feathers for examination under a light microscope for ectoparasites and feather pulp examination. • Examine uropygial (preen) gland, cloaca, and feet. • Auscultate heart, lungs, and air sacs. • Palpate abdomen. • Anesthesia may be required with birds difficult to handle safely (Fig. 8-9). Investigations 1. Routine hematology and biochemistry a. Zinc and lead levels may be appropriate to investigate low-grade heavy metal poisoning. Collect samples for zinc in either heparin or plain tube (without gel as this may contain zinc). Although blood levels can be indicative of zinc toxicity, there is no absolute correlation between blood zinc levels and clinical signs. As a general rule, if zinc levels are >32 to 50 pmol/L and there are consistent clinical signs (see Neurologic Disorders and Gastrointestinal Tract Disorders), then zinc toxicity should be suspected. Significant zinc levels are often accompanied by an absolute or relative monocytosis. 2. Aseptic collection of samples for bacteriology/mycology 3. Cytology 4. Radiography: A standing view using horizontal beam is useful for detecting metallic foreign bodies in the conscious bird; otherwise lateral and ventrodorsal views, under general anesthesia (GA), are required for meaningful radiography. 5. Endoscopy 6. Serology for PBFD, polyomavirus, Aspergillus antigen, and Chlamydophila antigen should be taken if thought necessary. 7. Fresh fecal samples for parasitic examination; look for Giardia, nematode eggs, etc. Smears can be dried and stained. 8. Bulk fecal samples (collected over 3 to 5 days) can be submitted for Chlamydophila polymerase chain reaction (PCR). 9. Diagnostic imaging, including radiography and endoscopy 10. Biopsy a. Note: Eosinophilic dermatitis linked to Trichosporon asahii infection. Management • Optimize diet: Consider converting to pelleted foods, using multivitamin supplements, reducing seed intake, and increasing fruit consumption where appropriate. • Where there is significant feather loss, consider supplementary heating to counter loss of insulation. • Covering broad-spectrum antibiotics may be useful if there are obvious skin lesions. • If pruritic, consider analgesia—meloxicam (Metacam) oral suspension at 0.1 mg/kg body weight b.i.d. Do not use steroids. • Collars • Collars are inherently very stressful to parrots; they interfere with normal feeding (many parrots transfer their food to their mouth with a foot), flight, climbing, and crop function. They are heavy relative to the weight of the bird and generally alienate the bird from its immediate surroundings. They also do not address any underlying cause or pathology, and if these are not addressed then feather plucking/self- mutilation may resume when the collar is removed. • Therefore, collars should be used judiciously and on a case-by-case basis. • If possible, hospitalize the parrot for 24 to 48 hours to enable the bird to get used to the collar, as well as allowing any minor adjustments and reassessments to be made. • A collar should be removed only after the bird has been clinically well for a reasonable period of time, as it is likely that, as in other species, abnormal or triggering sensations will persist for some time following the clinical resolution of lesions. Early removal often results in repeat damage. TreatmentZspecific therapy • Ectoparasites • Ticks: Treat with ivermectin or fipronil. Remove ticks manually where possible. • Red mite and other species - Ivermectin at 0.2 mg/kg PO, SC, or IM. Repeat monthly as required - Light dusting with pyrethrin powder - Treat environment in case of red mite; painting woodwork may “seal in” mites. • Feather mites - Cis-permethrin powder - Fipronil spray applied to cotton wool; beware hypothermia in small birds due to evaporation of carrier. - Treat quill mites, sarcoptid mites, and quill wall mites as for feather mites. • Knemidocoptid mites (e.g., Knemidocoptes pilae): - Ivermectin at 0.2 mg/kg PO, SC, or IM. A small drop may be applied topically over the jugular vein or onto the back of the neck and seems to work well. Injection is not recommended in birds weighing Polyomavirus: In some countries such as the United States, vaccination may be available. The virus may persist in the environment for some time, so testing with PCR should be undertaken. • Bumblefoot: Usually requires surgical intervention; bird may need supportive dressing on affected foot to prevent reinfection of surgical site. If the condition is unilateral, be aware of pressure sores and other sequelae affecting the good leg due to bird shifting weight onto it. The self-mutilating parrot Self-mutilation, like stereotypies, is a form of abnormal repetitive behavior exhibited in captive parrots. Often psychological in origin, the alternative of an underlying causal disease should not be ruled out, either as differential diagnoses or as contributing factors. Epidemiologic evidence (Garner et al 2005) points toward there being an inherited susceptibility, an increased incidence in females, and a link to certain stressful environmental conditions. There are no “quick fixes,” and investigation is often prolonged and expensive. A methodical and holistic approach is required. This should take into account the background of the bird, its environment, its disease status, and its psychological well-being. Background • Species • Most common in African grey parrots and cockatoos (Cacatua spp.—Jayson et al 2014). • Macaws and cockatiels often begin with the wings and legs. • Amazon parrots and Moluccan cockatoos tend to mutilate skin rather than feathers. • African greys will denude all areas of skin from neck down. • Captive-bred/hand-reared (CBHR) or wild-caught? Wild-caught individuals may be more prone to parasitic or psychological causes, while nutritional causes may be more common in CBHR birds. Hand-reared parrots may never learn the normal, speciesspecific methods of preening. • Single or with others? If with others, are any of them showing similar signs? • House bird or aviary? Again parasites are more common in aviary than living rooms. If aviary, are others affected? Positioning the cage next to a wall is associated with increased risk of feather plucking (Jayson et al 2014). • Is the parrot a recent introduction/acquisition of unknown clinical history, or a long-standing pet of known clinical history that has not been exposed to any new birds? Note: Even long-standing pets can be at risk of "new bird” problems if introduced or exposed to other birds it has not previously been with (e.g., if the owner buys another bird or the parrot is boarded at the local pet shop). Length of ownership also increases the risk of feather plucking (Jayson et al 2014). • How long has the bird been self-mutilating? • Is it constant or recurrent, and if recurrent, is it associated with anything (time of year, owner holidays, perceived periods of sexual activity)? Does it occur at a particular time of day? • Was there an apparent initial trigger? Building work? New dog/child/partner? Birds not used to change may not tolerate it well. • Does the bird self-mutilate when owner is present? Or when absent? Self-mutilation is associated with owners who have one or more holidays per year (Jayson et al 2014). If seen, how does bird behave while self-mutilating? Does it appear pruritic, vocalize or scream, or even interrupt a favored activity to self-mutilate? • Try to find out what the bird's normal demeanor is. Is the bird normally relaxed, fearful, aggressive? • How has the self-mutilation progressed? Where did the bird start plucking and how did it progress? • How does the owner respond? In some psychological cases the noisy excitable response of the owner can become a reward for this behavior! Environmental Lighting • Photoperiod: Many of the birds kept as pets are equatorial in origin and so are physiologically attuned for a 12-hour day/night cycle. African grey parrots exposed to longer than 12 hours of darkness are more likely to feather pluck (Jayson et al 2014). • Intensity: The majority of psittacines are open scrub (budgerigars) or high canopy (parrots) species that are exposed to high-intensity sunlight. This would include UV light that may act as a natural antiparasiticide, bactericide, and fungicide. • Spectrum: UV lighting in particular may be important with vitamin D3 synthesis from precursors excreted by the uropygial gland. In mammals vitamin D is important for normal skin function, and this may also be the case in birds. Diet • Seed-based diets are inappropriate for sole, long-term maintenance of many psittacines. Fat and hence energy levels are too high and protein levels relatively low and of poor quality. They are also low in vitamin levels. • Attempt to wean onto newer pelleted diets. This can be difficult to do, plus anecdotally there seem to be occasional behavioral reactions to colorings used. Otherwise some basic research may be needed to ascertain suitable foods. Water • Amazons, African greys, and many others are from humid, tropical rainforest areas. A daily dowsing with water and consequent necessary preening may encourage normal feather and skin integrity. Daily spraying with lukewarm water or access to a bath is appreciated by many birds. Environmental toxins • Zinc, often from galvanized caging or cheap metallic toys: Blood levels can be indicative of zinc toxicity, but as with lead, there is no absolute correlation between blood zinc levels and clinical signs. As a general rule, if zinc levels are >32.0 to 50.0 pmol/L and there are consistent clinical signs (see Neurologic Disorders and Gastrointestinal Tract Disorders), then zinc toxicity should be suspected. Significant levels often accompanied by an absolute or relative monocytosis. Feather plucking can be associated with chronic low-grade zinc toxicity; gut problems may be seen as toxicity and can cause gut stasis. Acute poisonings can damage liver and kidneys, causing vomiting, polyuria, and hematuria. Consider radiography to look for metallic foreign bodies in the gizzard. • Other heavy metals such as lead, copper, and iron may cause similar signs. Treatment for zinc toxicity • Sodium calcium edetate at 35 mg/kg IM b.i.d. for 5 days, stop for 3 to 4 days, and then repeat. Continue until zinc levels fall. • Dimercaptosuccinic acid (DMSA) at 30 mg/kg PO b.i.d. for 10 days or 5 days per week for 3 to 5 weeks • Penicillamine at 55 mg/kg PO b.i.d. for 7 to 14 days • Tobacco smoke: May predispose to brittle feather production, as may an excessively dry atmosphere • Toys: Psittacines are gregarious creatures. Most live as a pair within a flock and are constantly interacting with their flock members. All single psittacines should have a toy “friend” that they can feed, huddle up to, beat up, and generally completely dominate. Other toys should be rotated or changed with great frequency. Particularly useful toys are: • Wooden objects, as these can be systematically destroyed, exercising the beak and claws, and occupying valuable time • Toys into which food can be placed and with which the parrot must work to obtain its food Findings on clinical examination • Note if the condition is symmetrical. Self-mutilation due to psychological causes is often not symmetrical in early stages. • Handle the bird: • Examine nares, beak, eyes, and buccal cavity, including choana. Look particularly for signs of vitamin A deficiency. • Examine skin; note signs of inflammation, hyperkeratosis, ulceration, trauma, and seborrhea. • Assess feather quality: • Stress lines—lines visible on the vanes of the feather that denote areas of poor quality of the barbs—may indicate that a significant stressor has happened to the bird at a crucial point in the development of that feather. This may have been a disease or nutritional deficiency. • Frayed, dirty, or matted feathers: Inappropriate size caging may cause repeated damage to the retrices of those birds with long tails such as parakeets and macaws. • Abnormal coloration may result from nutritional deficiencies, hepatopathies, or PBFD. • Examine for parasites: • Pluck one or two feathers for examination under a light microscope for ectoparasites and feather pulp examination. • Feather scoring: • This allows a structured approach to defining and monitoring the extent of the self-mutilation. A final score is arrived at and noted, allowing an objective view of improvement or deterioration to be assessed. Feather scoring may prove difficult with a recalcitrant bird and should GA be needed (e.g., for radiography), this would provide an ideal opportunity to assess this (Fig. 8-10). Investigations 1. A general blood screen is highly recommended. Especially interested in WBC count and differential, liver and kidney biochemistry, and zinc levels. 2. Blood samples for PBFD or polyomavirus PCR 3. Chlamydophila serology 4. Fresh fecal samples for parasitic examination; look for Giardia, nematode eggs, etc. 5. Bulk fecal samples (collected over 3 to 5 days) can be submitted for Chlamydophila PCR. 6. Diagnostic imaging, including radiography and endoscopy 7. Aseptic collection of samples for bacteriology/mycology 8. Biopsy Pathological causes of self-mutilation Refer to Skin Disorders. Otherwise significant conditions include: • Chlamydophilosis • Staphylococcus has been linked to feather-picking in a budgerigar and feather loss in an unspecified psittacine (Hermans et al 2000).
Fig. 8-10. Feather scoring system. From Meehan et al 2003a. • Aspergillus • Avian bornavirus (proventricular dilatation disease, PDD) • Other diseases, including hepatopathies and renal disease • Endocrinologic • Hypothyroidism—rare (see Endocrine Disorders) • Sex hormone disturbances: Self-mutilation can be associated with seasonal changes or sexual activity. May pick at leggings. It is normal in many species to remove a patch of feathers ventrally at nesting time to form the brood patch whereby eggs can be kept warm. Consider measuring serum estrogen or androstenedione levels. Possible sex predisposition toward females. Psychological causes of self-mutilation • Frequently overdiagnosed. Should only be considered when other etiologies have been reasonably eliminated. • True cause not yet elucidated. Adverse environmental stimuli likely to be involved in many cases (see Garner et al 2005); may in some cases be linked to commercial bird-rearing techniques and practices that nestling parrots are exposed to at a time of neurologic development with high psychological sensitivity and receptivity • Suggested manifestations include: • Attention seeking: Abnormal behavior is reinforced by the owner paying attention when bird self-mutilates. • Displacement behavior: In the wild stressful situations can be avoided by flying off. In captivity this may not be an option, and so fear/aggression may be channeled into exaggerated “normal” behavior such as preening.
• Boredom, including the concept of time budgets: In the wild, a parrot will spend a significant amount of time flying to and from roosts and food sources, interacting with flock mates, avoiding predators, and so on. In captivity this time void can be filled by extending other normal behavioral repertoires that it can undertake, such as eating (especially Amazon parrots) or preening. • Separation anxiety: The high intelligence of parrots suggests that this could be quite common. • Obsessive-compulsive disorders: Akin to stereotypic disorders—bird will stop favored activity just to pluck. Psychotropic drugs These should not be considered a first line of action; their use should be considered once a physical or environmental problem has been reasonably ruled out or addressed. Suggested medications include: 1. Amitriptyline at 1.0 to 5.0 mg/kg PO b.i.d. 2. Doxepin at 0.6 mg/kg IM or IV daily 0.5-2 mg/kg PO every 12 hours, or 2 drops of 5.0 mg/kg solution per 30 mL drinking water 3. Fluoxetine at 0.4 mg/kg PO daily 4. Haloperidol at 0.1 to 0.4 mg/kg PO daily a. Alternatively, dilute 3.0 mg into 1 L of fresh drinking water, offered fresh daily; increase the dose progressively by double dosing every 2 weeks until a dose of 12.0 mg/L is achieved. b. Continue treatment for at least 3 to 4 months before gradually withdrawing over a period of time. c. May induce Parkinson-like tremors, which disappear when drug is withdrawn d. Haloperidol works reasonably well with self-mutilating birds; behavior of the bird is likely to alter for the better long before feather improvements are seen. Management 1. Correct diet. Ideally change to pelleted foods. At the very least, begin supplementation with multivitamin and/or calcium (if appropriate). 2. Address any environmental issues such as photoperiod, irritants such as smoking, and so on. 3. Remove any metallic objects from the cage. 4. Consider environmental enrichment techniques (more/different toys; companion of same species if no risk of infection, etc). If left alone for long periods, consider leaving radio or TV on. Birds naturally inhabit noisy environments—silence usually means there is a predator about. Environmental enrichment (including provision of a conspecific companion) has been found to be beneficial in birds displaying both self-mutilation (van Hoek and King 1997) and stereotypies (Meehan et al 2003b, Meehan et al 2004). 5. If pruritic, consider analgesia—meloxicam at 0.2 mg/kg PO, IM body weight once daily. 6. Attend to any obvious wounds. Application of topical amorphous hydrogel dressings (e.g., IntraSite Gel, Smith and Nephew Healthcare Ltd) encourages secondary healing. 7. Where there is significant feather loss, consider supplementary heating to counter loss of insulation. 8. Undertake specific treatment regimens as results of tests dictate. 9. Avoid the use of collars unless absolutely necessary. May stress bird and interfere with normal behavior, including feeding and crop function. 10. Basic training—“Step up,” “Step down,” “No,” and “Stay”—can be useful in both interacting with the bird in a controlled manner and filling in valuable time. The ideal is to establish a parent-child or leader-follower relationship rather than a partnerpartner one. 11. Do not forget the owners. They are likely to be embarrassed at the state of the bird and feel guilty if they have been feeding their bird the wrong food or if some other managemental deficit is identified, but you need them on board for what is liable to be a prolonged haul. They must be encouraged not to lose heart, as improvement may take some time. Upper respiratory tract disorders Nasal tract Cere color in budgerigars is a secondary sexual characteristic; in most sexually mature males it is a smooth, bright blue structure, while in most females it has a rougher texture and is brown in color. Young female light blue birds may have a pastel blue cere, leading to incorrect sexing; these darken to a more normal female-type cere with maturity. Gonadal tumors may secrete inappropriate sex hormones that can lead to a change in cere color of adult birds. Rhinitis Viral • Paramyxovirus (see Lower Respiratory Tract Disorders) • Influenza A (orthomyxovirus—see Lower Respiratory Tract Disorders) Bacterial • Chlamydophilosis • Mycoplasmosis • Other bacteria
Fig.8-11. Blocked nares in an African grey parrot. Fungal • Aspergillus • Candida (see “Treatment” in Lower Respiratory Tract Disorders) Dietary • Hypovitaminosis A (see Nutritional Disorders) Neoplasia Other noninfectious problems • Choanal atresia • Allergies • Rhinoliths—require surgical removal followed by antibiotic cover; often linked to hypovitaminosis A (Fig. 8-11)
Investigations 1. Radiography 2. Rhinogram 3. Routine hematology and biochemistry 4. Culture and sensitivity 5. Endoscopy of choana 6. Biopsy Sinusitis • Typically presents as swelling of the infraorbital sinus • For possible etiologies, see “Rhinitis” above and Lower Respiratory Tract Disorders. • Bacterial • Mycobacterium spp. • Mycoplasmal • Fungal • Papillomas • Sunken eye sinusitis: Collapse of the outer delineating skin due to negative pressure in the infraorbital sinus, which results from blockage of normal connecting diverticuli. Should return to normal when sinus problem is resolved. • Neoplasia • Teratoma (Diaz-Figueroa et al 2005) • Thymoma (Diaz-Figueroa et al 2004) Treatment • Appropriate antibiosis • Flushing of the infraorbital sinus, followed by culture and sensitivity plus cytology as appropriate • Surgical removal of inspissated material Lower respiratory tract disorders Viral • Paramyxovirus • Avian pox virus (diphtheritic form) • Amazon tracheitis virus (herpesvirus) • Orthoreovirus • Influenza A (orthomyxovirus) • Adenovirus—interstitial pneumonia • PDD—secondary aspiration and inhalation pneumonia Bacterial • Mycoplasma spp. • Chlamydophilosis—primarily C. psittaci, but other serotypes occasionally encountered • Escherichia coli • Pseudomonas spp. • Bordetella avium • Mycobacterium avium • Others Fungal • Aspergillosis • Cryptococcosis Protozoal • Sarcocystis falculata (Coccidia) Parasitic • Tracheal mites Sternostoma tracheacolum (in small parakeets and cockatiels) • Air sac worms (e.g., filarid nematodes) • Cyathostoma and Syngamus spp. (rare) Dietary • Hypovitaminosis A • Squamous metaplasia of the respiratory tract predisposes to respiratory infections. Neoplasia • Glottal neoplasia • Hemangiosarcoma (Hanley et al 2005) • Hepatic neoplasia or other coelomic mass Other noninfectious problems • Tracheal foreign body—seed husk a common finding in cockatiels • Polytetrafluoroethane (PTFE) toxicity from overheating of Teflon • Inhalation of other fumes from fires • Abdominal disease (e.g., neoplasia, hemocoelom, yolk serositis) • Hypothyroidism (goiter) in budgerigars on a seed-only diet • Air sac rupture (usually pathological) • Cigarette smoke • Creosote • Anemia • Allergic, asthmalike conditions • Chronic pulmonary interstitial fibrosis (CPIF), especially in older Amazon parrots (Zandvliet et al 2001). Preexisting pulmonary damage or allergies may contribute to the etiology of CPIF. • Cardiovascular disease (see Cardiovascular and Hematologic Disorders) Findings on clinical examination • Dyspnea and tachypnea—can be very severe • Open-mouthed breathing • Change in voice—may cease "talking" • Sneezing • Head swinging and neck stretching. Forward-leaning and extended neck strongly suggests tracheal obstruction. • Coughing occasionally encountered, but is uncommon. Beware parrots that imitate their owner's cough. • Tail-pumping • Increased recovery time/exercise intolerance • Increased inspiratory sounds often associated with upper respiratory tract disease. • Increased expiratory sounds often associated with lower respiratory tract disease. • Abdomen may be distended (fluid, neoplasia, hemorrhage). • Subcutaneous air-filled swelling; may vary in size (ruptured air sac) • Yellow urates and peracute death common with Sarcocystis. Old World parrots are especially susceptible. Investigations 1. Radiography a. Ventrodorsal view is best for detecting abnormalities of the lungs and air sacs. b. Distension of abdominal air sacs indicates upper respiratory obstruction (e.g., tracheal fungal granuloma or seed husk). Table 8-5 Parrots and related species: Chlamydophila serology
2. Fluoroscopy 3. Routine hematology and biochemistry a. Very high heterophil count (15 to 40 ? 109/L) indicative of aspergillosis b. High PCV: 0.55 to 0.74 L/L in chronic pulmonary interstitial hyperplasia. Also often have a respiratory acidosis with a pH of 7.16 to 7.3 (normal, 7.35 ± 0.08), hypoxemia: PO2 of 33.69 to 52.77 (normal, 49.46 ± 7.62), and hypercapnia: PCO2 of 48.77 to 80.08 (normal, 37.92 ± 4.23) (figures from Zandvliet et al 2001) c. High aspartate transaminase (AST) and creatine kinase (CK), often with Saraxystis 4. Serology for Sarcocystis, Aspergillus, and Chlamydophila—ideally investigate with repeat sampling to assess rising titer, but screening tests may also be useful (Table 8-5) 5. Hemagglutination inhibition tests and ELISAs may be of benefit in detecting influenza A. 6. Culture and sensitivity a. Tracheal lavage; needs GA 7. Cytology 8. Endoscopic biopsy 9. Endoscopy a. Endoscopic examination of trachea and syrinx b. Air sacs and lungs (high-risk procedure) 10. Transillumination of trachea in small psittacines may reveal mites or nematodes (rare). a. Mite or nematode eggs may be detected in feces or sputum microscopic examination. 11. Fecal samples a. Chlamydophila PCR b. Modified Ziehl-Neelsen staining of fecal samples or PCR for mycobacteriosis Management 1. Reduce stress as much as possible. Placing bird in a darkened room may help. 2. Covering broad-spectrum antibiosis; may be given by nebulization 3. Provide oxygen support. 4. Nutritional support 5. Placement of a tube into a caudal air sac to allow normal breathing in cases of tracheal blockage 6. Bronchodilators (e.g., aminophylline 4.0 mg/kg PO or IM b.i.d.) 7. Mucolytics (e.g., bromhexine at 3.0 to 6.0 mg/kg IM or 6.5 mg/L fresh drinking water daily) TreatmentZspecific therapy • Foreign body • Remove if possible; may require endoscopy or tracheotomy • Emphysema • Physical tapping and draining of air from emphysematous lesions. May need to be repeated. If necessary, place a stent if it fails to resolve quickly. • Viral diseases • Provide supportive treatment and covering antibiosis. • Amazon tracheitis virus: Acyclovir at 10 to 40 mg/kg IV or SC t.i.d. • Influenza: Provide covering antibiosis. Potentially a zoonosis and reverse zoonosis, so avoid contact with infected people. • Paramyxovirus: Supportive treatment. Paramyxovirus A (Newcastle disease) is notifiable in the UK. • Chlamydophilosis • Enrofloxacin at 5.0 mg/kg IM daily or 12.5 mg into 100 mL drinking water fresh daily • Doxycycline - Doxycycline hyclate intravenous human preparation given 60 to 100 mg/kg IM every 5 to 7 days for 45 days - Doxycycline hyclate as an in-water powdered medication: Use deionized water. However, Flammer et al (2003) found that drinking water with 400 mg of doxycycline/L over a 14-day period failed to maintain therapeutic plasma doxycycline concentrations.
- In the same study, hulled seed coated with sunflower oil and doxycycline powder to a concentration of 300 mg of doxycycline hyclate/kg maintained therapeutic plasma doxycycline concentrations for 42 days without notable adverse effects. - Note: Birds may be intermittent excreters, so at least 3 consecutive negative samples should be achieved before ceasing treatment. • Bacteria: Appropriate antibiosis • Mycobacteriosis • Potential zoonosis. Consider euthanasia. • Two suggested treatment regimens (Rupiper et al 2000) are: - Ethambutol (200 mg), isoniazid (200 mg), and rifampin (300 mg) all crushed together and mixed with 10 mL of a simple syrup. This is administered daily according to Table 8-6. - Combination therapy of ethambutol (10 mg/kg PO b.i.d.), streptomycin (30 mg/kg IM b.i.d.), and rifampin (15 mg/kg PO b.i.d.)
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
