Features

Common mites of avian and exotic animal pet species are generally species specific (Table 15-1). Fur mites generally cause dandruff and patchy alopecia with little associated pruritus. The rabbit fur mite (Cheyletiella parasitovorax) is considered zoonotic, causing mild hyperemia and pruritus in humans. The ear mite, Otodectes cynotis, is commonly found in ferrets and can spread between cats and ferrets; therefore it is important to treat all susceptible pets in the household. The presence of black earwax in ferrets does not necessarily denote ear mite infestation. The rabbit ear mite, Psoroptes cuniculi, can cause such an accumulation of dry crusts that an upright ear can be weighted down into the lop-ear position. Demodex spp. are commonly demonstrated in hamsters greater than 2 years of age with concomitant Cushing’s disease. Hamsters are generally exposed to the mites when young but do not exhibit clinical signs until immunocompromised. Rabbits and guinea pigs with intense pruritus should be checked for their respective mites because this would be the most common differential. Birds, typically budgerigars and canaries, infected with Knemidokoptes generally show pitting of the beak and facial skin (budgerigars), or pitting of the skin of the legs (canaries). Snake mites (Oophyionysus spp.) can be found anywhere on the snake’s body, but typically they can be found around the eye or between the cleft of skin under the chin. Severe infestations in snakes can cause significant anemia. African hedgehogs kept as pets in the United States can present with Chorioptes spp. mites, resulting in quill loss and skin crusting and flaking.

TABLE 15-1 Common Mites of Avian and Exotic Animal Pets

Top Differentials

Differentials include superficial pyoderma, dermatophytosis, and trauma. Rabbit syphilis (Treponema cuniculi) is a differential in rabbits.

Diagnosis

Microscopy of skin scrapes (deep if suspecting Sarcoptes scabiei) or tape preparations for fur mites, demonstrating the parasite or ova.

Treatment and Prognosis

In general, the treatment for mites in most species is ivermectin at 0.2 mg/kg PO, SC, or preferably topically repeated in 10 to 14 days, with some important exceptions: never use ivermectin in turtles or tortoises—it can cause paralysis, coma, death as a result of their permeable blood-brain barrier; never inject ivermectin into birds, especially small birds, as the propylene glycol base can cause an anaphylactic reaction and death.

Do not hang mite treatments, such as those that contain paradichlorobenzene, on the side of the cage, as they may be toxic to birds and they do not rid the bird of mites.

In rabbits, selamectin has been shown to clear infection of ear mites with one dose. When treating rabbits for ear mites, it is important to not remove the crusts, as they will fall out within 1 week after treatment with very little trauma.

Hamsters with concurrent adrenal hyperplasia may respond to op’DDD.

Because snake mites spend time off the host, any porous material in the enclosure should be discarded, and nonporous surfaces can be sprayed with a well-shaken mixture of ivermectin at 5 mg/L water. The propylene glycol base does not mix well with water.

Consult Carpenter’s Exotic Animal Formulary for further drug information.

FIGURE 15-1 Acariasis.

Rabbit with a severe case of ear mites due to Psoroptes cuniculi.

FIGURE 15-2 Acariasis.

Rabbit with a typical mild case of ear mites due to Psoroptes cuniculi.

FIGURE 15-3 Acariasis.

Rabbit with scabies due to a Sarcoptes spp. mite. This rabbit had intense pruritus.

FIGURE 15-4 Acariasis.

Cockatiel with Knemidokoptes pili mite infestation, known as the scaly leg and face mite (side view).

FIGURE 15-5 Acariasis.

Cockatiel with Knemidokoptes pili mite infestation, known as the scaly leg and face mite (front view).

FIGURE 15-6 Acariasis.

Cockatiel with Knemidokoptes pili mite infestation, known as the scaly leg and face mite (view of plantar surface of foot).

FIGURE 15-7 Acariasis.

Budgerigar with severe case of Knemidokoptes pili mite infestation, known as the scaly leg and face mite, which has caused deformation of the beak.

FIGURE 15-8 Acariasis.

Ball python with retained spectacle over the eye due to Oophinysus spp. mite infestation. The mites live in the crypt around the eye and interfere with normal shed in this area.

FIGURE 15-9 Acariasis.

African hedgehog with Chorioptes spp. mite infestation. Loss of quills and dry, flaky skin are typical, as is pruritus.

Features

The mouse louse (Polyplax serrata) is common in wild mice, causing anemia, debilitation, and intense pruritus. If it is found in pet mice, there is usually exposure to wild mice. The spined rat louse (Polyplax spinulosa) is rare but can cause pruritus, irritability, and anemia. The lice of guinea pigs (Gliricola porcelli, Gyropus ovalis) are commonly seen in pet guinea pigs, and if heavy in number can cause pruritus, rough hair coat, and alopecia. Typically, infestation with Gyropus spp. is associated with intense pruritus. Bird lice are uncommonly seen in pet parrot-type birds but are commonly seen in backyard poultry and peafowl. The chicken head louse (Cuclotogaster heterographus) is found about the head of chickens and peafowl. The chicken body louse (Menacanthus stramineus) is found near the vent of a variety of domestic fowl, including chickens, peafowl, guinea fowl, quail, pheasant, ducks, and geese.

Top Differentials

Differentials include other ectoparasites.

Diagnosis

Microscopy of tape preparation or plucked hair demonstrates the parasite or the ova (nits).

Treatment and Prognosis

In general, the treatment for lice is ivermectin at 0.2 mg/kg PO, SC, or topical, except for these important exceptions: never use ivermectin in turtles or tortoises—it may cause paralysis, coma, or death because of their permeable blood-brain barrier; never inject ivermectin IM into birds, especially small birds, as the propylene glycol base can cause an anaphylactic reaction and death. Other susceptable animals in the group should be treated as well as the environment.

Consult Carpenter’s Exotic Animal Formulary for further drug information.

FIGURE 15-10 Pediculosis.

Pet rat infested with unidentified lice. Lice and nits were visible with the naked eye over the entire dorsum.

FIGURE 15-11 Pediculosis.

Guinea pig infested with unidentified lice, but probably Gliricola spp. because this animal was not pruritic. Lice and nits were visible with the naked eye over the rump area.

FIGURE 15-12 Pediculosis.

Chicken with unidentified louse on feathers.

Features

Recently imported parrots may occasionally have a subcutaneous mass of adult Pelicitus spp. nematodes. Recently imported reptiles, including day geckos, may have a coelomic or SC mass of adult Thamagadia or Magnathamagadia spp. Rabbits that graze outside or are fed fresh-cut grass from outside can get Cuterebra spp. bot larva subcutaneously. The Cuterebra is ingested and migrates out of the oral cavity or esophagus to a subcutaneous site and is distinguished by the presence of a breathing hole in the skin.

Top Differentials

Differentials include neoplasia, abscess, or other granuloma.

Diagnosis

In reptiles and birds, the roughly 1 × 1-cm SC mass may have a vermiform shape. In rabbits, the roughly 4 × 2-cm SC mass will have a tell-tale breathing hole, and sometimes movement can be observed through the breathing hole under the skin.

Treatment and Prognosis

Surgical removal is best.

For rabbits, remove the parasite under general anesthesia by surgically incising the skin in each direction from the breathing hole, taking care not to traumatize the parasite to prevent release of parasite antigen. Clean and débride the wound and leave open to heal by second intention, with daily cleansing.

For birds and reptiles, surgical removal, cleansing, and primary closure is usually best.

FIGURE 15-13 Subcutaneous Parasites.

A day gecko with Magnathamagadia or Thamagadia spp. nematode SC. These were easily surgically removed. Later, the same nematode was found in the coelomic area.

FIGURE 15-14 Subcutaneous Parasites.

A recently imported parrot with Pelicitus spp. nematodes SC. These were easily surgically removed. Diagnosis was made in this case by visualization of nematode ova on cytological examination of an aspirate of the mass.

Features

Maggots are seen most commonly in the perineal area of rabbits housed outdoors and wild bird patients after trauma. A variety of ticks can infest domestic rabbits housed outdoors or wild rabbits. Fleas are occasionally seen in rabbits and ferrets, with ferrets seeming particularly susceptible to heavy infestations and subsequent fatal anemia. Pruritus is generally mild.

Diagnosis

Direct visualization of maggots, fleas, or ticks on skin.

Treatment and Prognosis

Maggots: Direct removal, or can use Capstar PO (nitenpyram 1 mg/kg PO).

Fleas: In general, the treatment for fleas in ferrets is similar to that for cats. Rabbits on the other hand should never be given fipronil (Frontline) as it causes seizures and/or death in rabbits. Rabbits can be given imidocloprid (Advantage) or pyrethrin products.

Ticks: Direct removal. Recently imported animals with ticks should have the ticks submitted for identification to be sure they are not foreign. Always save parasite specimens in 70% alcohol, never formalin, as formalin renders physically indentifying structures on the parasite unusable.

FIGURE 15-15 Myiasis, Flea or Tick Infestation.

Wild cottontail rabbit infested with unidentified tick species.

FIGURE 15-16 Myiasis, Flea or Tick Infestation.

Recently imported ball python with a flat-bodied snake tick. This tick was submitted for identification and was found not to be a species that could bring heartwater disease into this country from Africa.

Features

This sexually transmitted disease of rabbits causes crusting and erosive lesions of the skin and mucocutaneous junctions of the perineum, periocular and perioral areas, and sometimes the base of the ear. This disease is NOT zoonotic; human syphilis is caused by T. pallidum. The incubation period is long, approximately 3 to 6 weeks. Males without obvious signs can transmit the disease.

Top Differentials

Differentials include acariasis (see Figure 15-3) and papillomavirus, (see Figure 15-45), which typically involve other areas of the body than the mucocutaneous junctions.

Diagnosis

Diagnosis is often based on typical clinical signs and response to treatment, but a definitive diagnosis can be obtained by identifying the organism on biopsy or via direct microscopic examination of the fluid obtained after removing superficial crusts and squeezing the skin. After a few drops of saline are added and the condenser is turned down on the microscope, the motile bacteria can be seen.

Treatment and Prognosis

Sometimes this is a self-limiting disease. If the rabbit is to be bred or the lesions are troublesome, then treatment is recommended with procaine penicillin G with benzathine given subcutaneously ONLY every 7 days for 3 treatments. Remember never to give rabbits oral penicillin as this may cause fatal enteritis.

Consult Carpenter’s Exotic Animal Formulary for further drug information.

FIGURE 15-17 Rabbit Syphilis.

Perineal region of the same rabbit as in Figure 15-18, with typical mild to moderate case of rabbit syphilis caused by Treponema cuniculi. Lesions are near mucocutaneous junctions.

FIGURE 15-18 Rabbit Syphilis.

Young adult, female rabbit with typical mild to moderate case of rabbit syphilis caused by Treponema cuniculi. Lesions are near mucocutaneous junctions.

FIGURE 15-19 Rabbit Syphilis.

Rabbit syphilis after treatment. Same rabbit as in Figure 15-18, after 3 weeks of treatment with subcutaneous procaine benzathine penicillin every 7 days.

Features

The causes of ulcerative pododermatitis in rabbits include obesity, genetically sparse hair cover over the plantar surface of the “hock” (actually the plantar surface of the proximal metatarsus), and trauma from wire-only substrate or carpet, causing shearing forces on the hair. The hair provides the cushion for the plantar surface. Mild pododermatitis includes alopecia and hyperemia of the intact skin. Moderate pododermatitis involves breakdown of the skin with erosions, scabs, proliferative tissue, and swelling or infection of skin. Severe pododermatitis with osteomyelitis can easily occur because there is very little soft tissue coverage in this area. Guinea pigs present with this same disease, but the cause is usually unsanitary conditions past or present, and it is very difficult to treat.

Captive raptors commonly present with pododermatitis because they stand most of the day. It has been shown that during flight, the temperature and blood supply to a raptor foot increase dramatically. The plantar surfaces of the digits and tarsometatarsal area are more commonly affected in raptors, passerines and small psittacines, whereas parrots are usually affected on the plantar surface of the tarsometatarsus. Small or uniform-size perches, hypovitaminosis A, obesity, and “sitting back on the hocks” are usual causes in pet parrots.

Top Differentials

Perhaps a tumor, such as a fibrosarcoma, could form a mass in this area on a rabbit that may look like pododermatitis or trauma from other causes.

Diagnosis

Diagnosis is based on direct visualization. A radiograph can determine if there is osteomyelitis.

Treatment and Prognosis

Birds

Birds with mild pododermatitis may improve with husbandry changes such as a wider perch, a perch with varying diameters, a padded perch, improved diet with less fat or fewer calories or with needed vitamin A, and, most important, increased exercise. If infection is present, then surgery or long-term antibiotics based on culture (both aerobic and anaerobic) and bandaging may be necessary. A variety of bandages have been described, such as “ball,” where the foot is bandaged into a ball; “snowshoe,” where the bandage is flat-bottomed to disperse the weight over a larger surface area; or a bandage that puts no weight on the bottom of the foot because a U-shaped bar is strapped to the leg. The prognosis is guarded to grave for moderate and severe pododermatitis, respectively.

FIGURE 15-20 Ulcerative Pododermatitis.

Rabbit with moderate case of ulcerative pododermatitis that has eroded through the skin and developed a scab with inflammation on the plantar surface of the foot.

FIGURE 15-21 Ulcerative Pododermatitis.

Radiograph of a rabbit with a severe case of ulcerative pododermatitis that includes osteomyelitis of the tarsus and tibiotarsal joint.

FIGURE 15-22 Ulcerative Pododermatitis.

Raptor under anesthesia with a severe case of ulcerative pododermatitis (bumblefoot) on the plantar surface of the foot. The affected area of the foot is typical for raptors.

FIGURE 15-23 Ulcerative Pododermatitis.

Duck with a moderate to severe case of ulcerative pododermatitis (bumblefoot) on the plantar surface of the foot. The affected area of the foot is typical for Anseriformes (ducks, geese, swans).

FIGURE 15-24 Ulcerative Pododermatitis.

Amazon parrot with a mild case of ulcerative pododermatitis. This case started as hypovitaminosis A from an all-seed diet, causing unhealthy, thin skin predisposing to plantar erosions.

Features

Mycobacteriosis caused by Mycobacterium avium, Mycobacterium genovense, and other species has been described periodically in parrots. A rare cutaneous form has been described and presents as nonhealing raised lesions over the legs that do not heal or respond to typical antibiotics. The typical form of mycobacteriosis in birds generally affects the hepatic and gastrointestinal (GI) systems.

Top Differentials

A slow-healing secondarily infected traumatic wound may resemble this lesion.

Diagnosis

A histopathologic diagnosis of a chronic granulomatous lesion with no obvious organisms should be suspicious of mycobacteriosis and further testing should be pursued. Mycobacteria spp. can be detected on special stains of a biopsy sample. Specifically, a Fite’s modified acid-fast stain should be requested because a regular acid-fast stain may destroy the delicate types of mycobacterial species that infect birds. A PCR test can also be performed on tissues.

Treatment and Prognosis

Euthanasia, not treatment, is recommended because of the zoonotic potential of this disease, which is historically difficult to treat in people and can be fatal. Nevertheless, treatments have been attempted with three to five medications, including ethambutol, given daily or twice daily for a year or longer, with documented recurrence after medication is stopped. Check with your local health department regarding the legal implications of treating an animal in your area.

FIGURE 15-25 Mycobacteriosis.

Amazon parrot with chronic nonhealing wounds on the leg caused by Mycobacterium kansasii. The parrot was euthanized after confirmatory diagnosis with a Fite’s modified acid-fast stain and polymerase chain reaction (PCR) performed at washington State Diagnostic Laboratory.

Features

It is not common for birds to present with a bacterial dermatitis unless it is involving the plantar surface of the foot, as described under ulcerative pododermatitis, or there is underlying trauma that allowed the infection to start; if present, this generally involves gram-negative bacteria. A ferret developed suspected allergy and secondary Pseudomonas spp. dermatitis after the owner built it a cage made of redwood. After removal of the new homemade cage and appropriate antibiotic treatment, the ferret made a complete recovery.

Top Differentials

Fungal infection or neoplasia.

Diagnosis

Diagnosis usually involves aerobic and anaerobic culture and sensitivity, but may also include cytology, biopsy, or fungal culture. No allergy testing has been reported in ferrets. In this case, suspicion was high because the disease occurred after exposure to the new cage.

Treatment and Prognosis

Clean and débride the wound; this is sometimes repeated over the course of days. Primary closure is performed once infection is controlled. Birds’ heterophils lack myeloperoxidase, an enzyme that liquefies pus; therefore do not place drains in the wound. Contaminated wounds are treated as in other animals. Antibiotic is based on culture.

FIGURE 15-26 Bacterial Dermatitis.

Wild great horned owl with a porcupine quill through the skin under the left eye. The quill was removed under anesthesia and the wound cleaned to heal by second intention healing.

FIGURE 15-27 Bacterial Dermatitis.

Close-up of owl in Figure 15-26.

FIGURE 15-28 Bacterial Dermatitis.

Captive adult bald eagle with a supraorbital SC abscess.

FIGURE 15-29 Bacterial Dermatitis.

Same captive adult bald eagle with a supraorbital SC abscess after surgical removal.

FIGURE 15-30 Bacterial Dermatitis.

Young adult ferret with severe bacterial dermatitis due to Pseudomonas aeruginosa. The owner had recently hand-made an enclosure of redwood for the ferret, and although this was not proved, it was suspected that the ferret was allergic to the redwood. The ferret responded well to appropriate antibiotic therapy based on culture.

FIGURE 15-31 Bacterial Dermatitis.

Same ferret as in Figure 15-30, with bacterial dermatitis showing plantar surface of foot.

FIGURE 15-32 Bacterial Dermatitis.

Adult leopard gecko with severe case of dysecdysis (abnormal shedding) with two or three successive sheds still in place. A culture of the green ocular discharge grew Pseudomonas aeruginosa.

FIGURE 15-33 Bacterial Dermatitis.

Same gecko as in Figure 15-32 showing dysecdysis (abnormal shedding of the entire body). Retained sheds on toes have a constricted blood supply and cause necrosis of the toes. This gecko ended up responding to appropriate antibiotic therapy based on culture and multiple warm water soaks but lost almost all its toes.

FIGURE 15-34 Bacterial Dermatitis.

Ventral surface of snake (boa) with bacterial dermatitis secondary to a burn.

Features

Bacterial sepsis in reptiles can manifest as hyperemia of the ventrum in turtles or snakes, and as hyperemic conjunctiva in lizards. Historically, Pseudomonas and Aeromonas are the most common bacterial isolates from reptiles. Occasionally, boa-type snakes can also develop a cellulitis at the site of infection, which causes tremendous swelling. Snakes normally shed in one piece, whereas lizards shed in a piecemeal fashion from head to toe. Snakes will shed the spectacle over the eye first, turning the bluish color of the eye clear, which marks the beginning of a shed. Then, the snake sheds (ecdysis) the entire skin in one everted piece. Dysecdysis is an abnormal shed and is usually due to low humidity in the environment. During the week before and after a shed, a snake can mimic respiratory disease because of partial occlusion of the nares, and they may also develop a hyperemic ventrum.

Top Differentials

Localized skin or shell infection on the ventrum can also present with hyperemia, but it is usually localized—not generalized. Days to weeks before a normal shed, a snake can mimic sepsis, showing a hyperemic ventrum and even increased respiratory sounds. A haziness to the skin and a “bluing” of the spectacle (scale over the eye) occurs just before a shed due to increase in lymph fluid under the spectacle. Inclusion body disease caused by a retrovirus-like agent can cause an abnormal shed, as well as neurologic signs. Sepsis can also cause a hyperemic ventrum. Respiratory disease can cause wet crackles.

Diagnosis

If the skin blanches with digital pressure, it is hyperemia, and not the pigmentation of the animal.

Treatment and Prognosis

Find the source of infection, obtain a culture or blood culture, and treat with appropriate antibiotics. Antibiotic treatment in reptiles is routinely given for 6 to 10 weeks. To encourage a shed, the reptile should be soaked in warm water. Never pull off the shed, especially the spectacle over the eye, as skin or corneal damage may occur. The old shed can be gently rubbed off in the water. Increase humidity in the habitat by adding a wide, shallow dish of water big enough for the reptile to soak on its own.

FIGURE 15-35 Sepsis.

Ventral hyperemia of the plastron of a red-eared slider turtle secondary to sepsis from bacterial pneumonia.

FIGURE 15-36 Sepsis.

Close-up of turtle in Figure 15-35.

FIGURE 15-37 Sepsis.

Ventral hyperemia of the scutes (scales) of an amelanistic snake secondary to sepsis from a bacterial pneumonia.

Stay updated, free articles. Join our Telegram channel

Join