Rabbit Diseases Bacterial and Mycotic Diseases At the
Rabbit Diseases Bacterial and Mycotic Diseases At the conclusion of this program, you should be able to state the significance and etiologic agents of the following diseases in rabbits maintained for research, testing, or teaching: Pasteurellosis, enterotoxemia, mucoid enteropathy, treponematosis, mastitis, Tyzzer's Disease, and superficial mycosis. Pasteurellosis Snuffles
Most common disease of domestic rabbits Etiology: Pasteurella multocida It is a bacterial infection that gains access to the nasal cavity, then migrates to almost any organ in the body. It can migrate via the eustachian tube to the ear, via the nasolacrimal duct to the conjunctiva, or by way of the trachea to the lungs. It can be carried by the blood stream, to cause abscesses and lesions in internal organs, such as heart, lungs, and reproductive systems. It can also gain access through skin wounds to cause subcutaneous abscesses.
Pasteurellosis Snuffles Clinical Signs: The classic clinical manifestation of pasteurellosis is a mucopurulent nasal discharge that can be accompanied by sneezing, coughing, and snuffling sounds.
These signs account for the common name of "snuffles" that is given to the condition. Clinical signs cont Exudate on
forepaws The nasal exudate may be wiped onto the medial aspects of the forepaws Signs -- red eye The signs of pasteurellosis will
be related to impairment of the organs that are involved. The conjunctiva may be red and swollen with serous to purulent exudate that may mat on the fur. Torticollis
Torticollis, or head tilt, may be seen as the result of middle or inner ear infection, or subcutaneous abscesses may be found. Pyometria
This image shows a pus-filled uterus (pyometria) caused by pasteurella infection. Uterine involvement will result in sterility and possibly a vaginal discharge Diagnosis: culture - -
Pasteurellosis is caused by Pasteurella multocida, a small, gram-negative, bipolar staining, ovoid rod that produces an endotoxin. Most isolates form circular, convex, smooth white colonies on dextrose starch or blood agar, as seen on this image
Transmission Rabbits can be infected prior to weaning by contact with infected dams. Post weaning, the disease can also be transmitted by direct contact or by fomites.
The disease can also be transmitted venereally if the reproductive organs are infected. Aeorsol trans-mission can occur, but it is not as likely a method of transmission as direct contact. Summary of clinical findings/confirmation A presumptive diagnosis of pasteurellosis is made from the common clinical findings:
nasal discharge, sneezing and snuffling sounds, conjunctivitis, torticollis, subcutaneous abscesses, swollen testicles, vaginal discharge, sterility. A definitive diagnosis is made by isolation and identification of Pasteurella multocida from the affected tissues. Necropsy - exudate in nasal passages
This is the longitudinal section of the head of a rabbit that has had severe nasal discharge. The necropsy showed mucopurulent exudate in the nasal passages and sinuses. Necropsy - pneumonia
Necropsy may also reveal areas of consolidation in lungs, seen here as the more intensely colored lower portions of the lung lobes or abscessed lungs with consolidation, as seen on this image.
Treatment Antibiotics are sometimes used in an attempt to treat pasteurellosis. Many strains are sensitive to penicillin. Injections of 40,000 IU of penicillin G per kilogram of body weight may be given IM at 8-hour intervals for 7- 10 days. Another antimicrobial reported to be effective is trimethoprim/ sulfamethoxizole (24% suspension)
at a rate of 0.125 ml per kilogram of body weight, given subcutaneously in a single daily dose or divided into two doses. And recently Enrofloxacin, at a dose of 5 mg/kg of body weight, has been reported as an effective treatment. Snuffles Treatment/control Strict culling of infected animals is practiced in some
colonies, and may be useful in the control of the disease. Cultures of the deep anterior nares, ELISA Prevention pasteurellosis is best accomplished by purchasing animals from a pasteurella-free colony and
isolating them to prevent exposure to P. multocida Enterotoxemia/colitis Enterotoxemia is a peracute to subacute disease most commonly seen in weanling rabbits Infection by Clostridium and production of Clostridial toxins -- most commonly the toxin
produced by Clostridium spiroforme. Factors that can upset normal homeostasis include changes in feed, temperature fluctuations, stress of weaning, and administration of antibiotics, including lincomycin, ampicillin, amoxicillin, clindamycin, erythromycin, and penicillin Clinical signs The primary sign associated with subacute disease is
profuse watery diarrhea. The perineum, medial and caudal surfaces of the rear legs, and the lower abdomen will be covered with greenish to "tarry" black-brown fecal material. Sometimes there will be blood in the feces, as shown on this image.
Diagnosis Gram staining This field is filled with the organisms, which have an easily recognizable helicallycoiled semicircular shape.
Treatment Treatment is generally not successful, especially in the acute cases. There are some reported successes with use of metronidazole, especially when combined with terramycin Necropsy Necropsy will show
hemorrhages, frequently in a paintbrush conformation on the serosa of the cecum (as seen on this image), Treponematosis Syphilis Etiology: Treponema
paraluis-cuniculi Treponematosis is also known as rabbit syphilis, vent disease, or venereal spirochetosis. The disease is contracted venereally or by young rabbits in contact with an infected dam. Clinical signs
The disease is characterized by dry, crusty exudate overlying ulcers in the skin and mucous membranes. Lesions commonly occur on the vulva (shown here), prepuce, and anus. Typical lesions
Lesions can also occur on the nose, eyelids, and lips. This shallow ulcer is typical of treponematosis. Diagnosis Diagnosis is confirmed by Darkfield examination
of scrapings from the lesions for the presence of the spirochete Treponema paraluiscuniculi. Treatment Treponematosis can be treated successfully with three
injections of Benzathine penicillin with procaine penicillin G, 84,000 IU/ kg given IM at 7-day intervals. All animals from an infected colony must be treated to eradicate the disease There are NO public
health hazards associated with the disease. Mastitis Mastitis in the rabbit is similar to acute mastitis in other species. It affects lactating does and occasionally also occurs in does with pseudocyesis, or false pregnancy. The most commonly involved bacteria are Staphylococcus aureus,
Pasteurella multocida, and Streptococcus spp. The mammary glands become swollen, firm, and hot. Additional signs are fever and loss of appetite.
There may be illness and death among the pups. Death of the doe may follow due to bacterial toxemia and septicemia Treatment/control Affected does should be isolated and given penicillin G- 60,000 IU/kg twice daily for 3 - 5 days. Pups should be disposed of, as they may spread the disease if allowed to nurse on
another doe. Hand raise? Tyzzer's Disease Tyzzer's Disease occurs in rabbits. It is characterized by acute watery diarrhea. The disease often causes death 6 to 48 hours after the onset of clinical signs Review from rodent species
MYCOTIC DISEASES The only mycotic disease of rabbits that is likely to require veterinary care is dermatophytosis, commonly known as ringworm. Etiology: Trichophyton mentagrophytes Clinical signs
It is a superficial infection characterized by patchy areas of hair loss, most commonly on the head. The lesions are pruritic, and there may be secondary spread to paws and other parts of the body. Clinical signs
The lesions tend to spread outward; and are dry, crusty, and scalely at the periphery. Dermatophytosis is a zoonotic disease, and gloves and other protective clothing must be worn when handling animals that may be affected. Diagnosis Dermatophytosis is seen more commonly in pets and backyard rabbitries than in laboratory colonies, because of higher
hygienic standards in laboratories. DTM??? Treatment Lesions can be treated topically with antifungal agents, but this is best combined with griseofulvin treatment. Griseofulvin can be administered orally by gavage at a level of 25 mg/kg of body weight or in the feed at 0.750 gm/kg of feed. Treatments should be continued for 14 - 21 days.
PARASITIC, PROTOZOAL, AND VIRAL DISEASES Parasitic Diseases The primary parasitic diseases that we will consider in this program are ear mite infestation or otoacariasis, caused by Psoroptes cuniculi, and fur mite infestation caused by Cheyletiella parasitivorax
Ear mite Ear mite infestation is very common in rabbits. The first evidence is a dry, brown, crusty material deep in the external ear canal. Exudate
A common way to treat the disease is to tranquilize the rabbit, soften the crusty material with a bland mineral oil, and remove the debris from the external ear. With careful inspection of the exudate you can
see the mites, Psoroptes cuniculi, without the aid of magnification. Ear mite, microscopic Under the microscope, you can see that the legs of the mites have suckers on the end of long, jointed
stalks. The eggs show as whitish bean-shaped structures Treatment After cleaning out as much as possible of the crust, a commercially available product containing an insecticide is
applied to both ears. An alternative treatment is a single or biweekly subcutaneous injection of Ivermectin, at 400 mcg/kg. The disease may recur with either treatment Fur mite moving dandruff Another mite that affects rabbits is the fur mite, Cheyletiella parasitivorax. It is a condition that is more common in pet rabbits than in
laboratory rabbits Clinical signs As contrasted with ear mite infestation, there is usually no clinical disease, but severe infections may produce hair loss and an oily scale.
The condition is zoonotic, and care should be taken to prevent contact with Cheyletiella parasitivorax. Mite, microscopic The mite is a surfacedweller and does not burrow into the
epidermis. The lesions are not pruritic Diagnosis and Treatment Diagnosis is by clinical signs of mild dermatitis and by microscopic identification of the mites obtained by brushing the skin and hair or by scraping the skin. Carbamate or synthetic pyrethroid powders are recommended for
treatment of rabbits affected by fur mites, according to the label instructions given for cats Viral Diseases Myxomatosis Although viral diseases of laboratory rabbits are rare, outbreaks of myxomatosis are seen occasionally in production colonies in West Coast states of the United States. The disease is endemic in Europe,
Australia, and South America. Noninfectious Diseases Three categories Noninfectious diseases of rabbits can be classified as: -neoplasias, -heritable diseases, -management-related diseases. All are causes of morbidity and
potential mortality in rabbits. Neoplasias-Uterine adeno carcinoma Uterine adenocarcinoma is the most common neoplasm of rabbits.
Firm, ovoid, hemorrhagic nodules form along the mesometrial junction. They can be seen on either side of the cervix in this image. Late in the disease, metastasis occurs, and death results. Prevalence The disease is common in females that reach 5 years of age, with
prevalence that may exceed 50%. Under the age of 3 years the prevalence is only 4%. Clinical signs Early clinical signs of uterine adenocarcinoma are lowered fertility, smaller than normal litters, abortions, resorbed fetuses, or stillbirths. The early signs may be followed by a bloody vulvar discharge
Diagnosis The diagnosis is aided by palpation of the abdomen to detect multiple nodules in the uterus and confirmed by histologic identification of the tumor.
Treatment Hysterectomy may be an effective treatment if it is done and prevention before metastasis occurs. If females are to be kept to an old age, they may be spayed as a preventive measure.
Other neoplastic Other neoplasms that rabbits are susceptible to are (in diseases order of their frequency): Lymphosarcoma. Embryonal nephroma. Bile duct adenoma. Heritable diseases The second category of noninfectious
rabbit diseases is inherited conditions: buphthalmia, splay leg, and mandibular prognathism Buphthalmia Buphthalmia is a congenital abnormality in production and removal of aqueous
humor from the anterior chamber of the eye. Early signs on affected rabbit will have increased anterior chamber size, possibly with slight cloudiness of the cornea. Advanced clinical signs
Later, there will be progressive opacity, increased prominence of the eyeball, and conjunctivitis. There may be ulceration and rupture of the cornea with scarring and vascularization; and the general vigor of the rabbit may be reduced.
The condition is most common in rabbits of the New Zealand White breed Buphthalmia - Characteristics Genetically, it is autosomal recessive with incomplete penetrance There is no evidence of pain, although vision will be affected and there may be a loss of vigor. There is no need for medical intervention; however animals with signs of this condition should not be bred.
Tonometer use Buphthalmia is sometimes used as a model of glaucoma in humans, as both result from disturbances in production and removal of aqueous humor. This image
shows measurement of the intraocular pressure Splay leg Splay leg is a progressive condition that is generally seen by the time the rabbit is 4 months of age.
An affected animal is alert but unable to adduct one or more of its limbs; therefore it attempts to move with a swimming motion. Treatment and Prevention Splay leg may be the leading clinical sign of any of several morphologic mutants. No treatment is known.
The condition is prevented through breeding selected stock that do not show signs of the condition. Mandibular prognathism The third inherited condition common to rabbits is mandibular prognathism, or malocclusion. Treatment
As a rabbit's incisor teeth grow 4" per year, it is necessary to clip them (but not too close) Dog nail clippers (Rescoe or White styles), bone or wire cutters and a rotary tool with disc attachment (shown in photo) may be used to
trim teeth. Care should be taken to prevent shattering the incisors. . Management-Related Conditions Five conditions that everyone using rabbits should be on guard for are: 1. ulcerative pododermatitis 2. traumatic vertebral dislocation/fracture 3.
gastric trichobezoars 4. moist dermatitis 5. nutritional deficiencies Ulcerative pododermatitis Ulcerative pododermatitis in rabbits is commonly called "sore hocks." Dry or abscessed lesions develop on the plantar
surface of the metatarsal area, due to pressure. They later develop into hyperkeratotic, chronic inflammation, and the rabbit will be reluctant to move. Predisposing factors Predisposing factors for pododermatitis include a rough
cage floor such as woven wire, a heavy, mature animal and, according to some, overgrown toenails. Treatment Treatment is directed
toward eliminating the causes and applying antiseptic or antibiotic ointment to the affected areas to speed recovery. A smooth, impervious resting board should be provided for the rabbit. If the animal is overweight, it should be placed on a restricted diet
Traumatic fracture/ dislocation Rabbits are subject to vertebral dislocation or fracture. Strong muscular contractions when a rabbit kicks can produce forces that dislocate or fracture the rabbit's relatively fragile vertebral column Radiograph
The diagnosis can be confirmed by radiography or necropsy. This radiograph shows a dislocation between vertebrae L4 and L5. The L7 vertebra is the most common site of fracture or dislocation. For cases exhibiting only
mild paresis, cage rest and parenteral steroids may result in recovery. If the animal is paralyzed, treatment will not be successful, and it should be humanely killed. Hairballs (Trichobezoar) Rabbits ingest hair by
normal grooming and as a result of hair pulling by females for nest building. It may then form a mat that fills most of the stomach. The facts that rabbits don't vomit and have a small pylorus are believed to contribute to hairball formation. Dwarf rabbits are more susceptible to this condition than larger rabbits
Observations The clinical signs are loss of appetite, absence of normal feces, and slow weight loss without other signs of disease. The animal will be bright and alert and will continue to
drink water. Treatment Sometimes the condition will resolve spontaneously. Laxatives or administration of protein-digesting enzymes such as
papain or bromelain, found in raw papaya and pineapples The only certain treatment is removal of the mass by gastrotomy. This image shows the opened stomach with the hair mat Prevention
Feeding a high-fiber diet or augmenting the diet with shredded wheat or longstemmed hay two or three times a week is suggested as a preventive measure. Moist dermatitis This image shows moist
dermatitis that resulted from drooling. The gross lesions consist of inflammation, alopecia, ulceration, and necrosis of the affected skin. Chronic wetness associated with dental problems, leaking watering systems, or continual contact with urine as result of poor husbandry practices predispose to the
condition Technician treating The underlying conditions causing chronic wetness must be identified and corrected. Then the animal can be treated by clipping nearby hair and applying
mild antiseptic scrubs and antibiotic ointments Vitamin A deficiency The clinical manifestations of Vitamin A deficiency include droopy ears as seen on this image. This is due to weakening of
cartilage. Pup with hydrocephalus Vitamin A deficiency impairs fertility in both sexes. Fetuses may be aborted or reabsorbed, or born with hydrocephalus, as shown in the lower pup on this image. Questions Credits The Laboratory Animal Medicine and Science
Series II has been developed by the following committee for the American College of Laboratory Animal Medicine C. W. McPherson, D.V.M., Chair J. E. Harkness, D.V.M. J. F. Harwell, Jr., D.V.M. J. M. Linn, D.V.M. A. F. Moreland, D.V.M. G. L. Van Hoosier, Jr., D.V.M. L. Dahm, M.S.
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