Rabbit Flashcards by Tom Chatkupt

Name the labeled structures

Alimentary tract from a mature rabbit, illustrating the

prominent gut-associated lymphoid tissue (GALT), including a Peyer’s

patch (A) in the wall of the ileum, the sacculus rotundus (B) at the

terminal ileum, the cecal tonsil (C) in wall of the proximal cecum, and

the cecal appendix (D) at the terminus of the cecum.

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Name the tissue type and common cell type present.

GALT from a normal mature rabbit, depicting the

common presence of histiocytes filled with refractile particulate debris

within the follicular center.

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Name the structure

Pulmonary artery of a normal rabbit. Pulmonary arteries

are highly muscular, which can be misinterpreted as muscular

hypertrophy.

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Describe the structure and its incidence

Female reproductive tract of a normal doe, depicting the 2

separate cervices, which is typical for this species. The uterus is

bicornuate, with 2 separate horns.

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Name the tissue, describe the lesion, name the cause

Integument from a rabbit with leporid herpesvirus 4

infection, depicting necrosis of the epidermis and papillary dermis with

underlying dermal hemorrhage.

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describe the notable structures (arrows)

Leporid herpesvirus 4 infection of the skin from a rabbit, depicting a multinucleate syncytium and intranuclear inclusion bodies (arrows) in the follicular epithelium.

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Cerebrum. Name the structures and causative agent.

Cerebrum from a rabbit with naturally acquired herpes

simplex virus encephalitis. Note the prominent intranuclear inclusion

bodies in neurons (arrows) and astroglia

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1) Causative agent, genus
2) Usual means of transmission
3) Potential sequalae in NZW

1) Cottontail rabbit papillomavirus, Kappapapillomavirus
2) Insect vectors, e.g. mosquitos and ticks
3) squamous cell carcinoma

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Describe. What is the most likely cause?

Solitary papilloma on the ear of a laboratory rabbit naturally infected with cottontail rabbit papilloma virus (CRPV).

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1) causative agent
2) means of transmission
3) potential sequale
4) describe histology

1) rabbit oral papillomavirus
2) direct contact, including does to kits
3) none - no reports of malignant transformation
4) basophilic intranuclear inclusions and viral antigen in the stratun spinosum

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1) tissue
2) arrow
3) cause
4) associated disease

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1) Describe the lesions
2) causative agent

1) Mucopurulent conjunctivitis, periocular swelling, and

facial edema (myxomatosis)

2) myxoma virus
3) family Poxviridae, genus Leporipoxvirus

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Tissue, arrows, cause

Intracytoplasmic inclusion bodies (arrows) in the

conjunctival epithelium of a rabbit with myxomatosis.

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tissue, pathology, cause

Lymph node, depicting hypertrophy and hyperplasia of stellate myxoma cells and severe lymphocytic depletion.

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Rabbit respiratory epithelium with intracytoplasmic inclusions (arrows). name the cause

Myxoma virus

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Cause

related to

Rabbit (Shope) fibroma

myxoma virus

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describe

arrows

cause

Skin of a Sylvilagus rabbit infected with Shope fibroma

virus. There is a dense network of fusiform to polyhedral fibroblasts in

the dermis, many of which contain prominent intracytoplasmic

inclusion bodies (arrows).

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Organ, gross description, cause

Lungs from a wild Oryctolagus rabbit with acute rabbit

hemorrhagic disease (RHD) virus infection. There is marked pulmonary

edema with multifocal ecchymoses.

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tissue, microscopic description, cause

Lung from a case of RHD in a feral Oryctolagus rabbit from Australia. Notemultiple intravascular thromboses

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organ, gross description, cause

Liver from a domestic rabbit naturally infected with

RHD virus. Note the granular texture of the hepatic capsule and

accentuated lobular pattern.

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tissue, microscopic description, cause

Liver from a rabbit experimentally infected with rabbit

hemorrhagic disease virus. Note the acute periportal and midzonal

hepatocellular necrosis.

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tissue, microscopic description, cause

Small intestine from a juvenile rabbit with a natural case

of epizootic rotaviral enteritis. There is submucosal edema, with

blunting and fusion of villi. Enterocytes within crypts and on villi are

immature, indicative of regeneration.

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tissue, microscopic description

Acute fibrinopurulent bronchopneumonia in a young

rabbit infected with Bordetella bronchiseptica. The terminal airway

and alveoli are flooded with fibrin-rich exudate.

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Tissue

agent

distribution

stain

Lung of a rabbit naturally infected with cilia-associated

respiratory (CAR) bacillus. This organism colonizes the epithelium of

the larynx, trachea, and bronchi in the rabbit. Note the prominent

peribronchiolar lymphocytic infiltration (Warthin-Starry stain).

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Organ description cause

Cecum from a rabbit with clostridial enteropathy. Note the hemorrhage and the fibrinous exudate on the mucosal surface.

Cecum of rabbit with Clostridium spiriforme. Describe the tissues

Necrotizing typhlitis from a case of clostridial enteropathy due to Clostridium spiroforme. Note the selective loss of mucosal epithelium with relative sparing of crypts and submucosal edema.

intestinal contents from a rabbit. Name the stain, name the organisms marked by the arrow.

Gram-stained smear of intestinal contents from a rabbit with clostridial enteropathy, demonstrating the typical coiled appearance of Clostridium spiroforme organisms (arrow).

Describe cause?

Acute necrohemorrhagic typhlitis in a rabbit with Tyzzer’s disease. Note ecchymotic hemorrhages on the serosa.

describe hallmark sign of?

Multifocal hepatic necrosis in an adult rabbit with Tyzzer’s disease.

describe cause? expected histologic lesions?

Acute gastric and intestinal tympany in a rabbit that died acutely with epizootic rabbit enteropathy. The stomach and intestine are distended with gas and fluid, but histologic lesions are minimal or absent in this syndrome.

weanling rabbit with profuse diarrhea. cause?

Intestine from a weanling rabbit with profuse diarrhea associated with acute infection with an attaching and effacing enteropathogenic Escherichia coli (EPEC). Note the fluid content that has leaked from an incision in the small intestine (arrow).

organism? Stain?

Cecum from a case of acute coliform enteritis in a weanling rabbit. The surface mucosa is densely populated with attaching Escherichia coli (Warthin–Starry stain).

describe

Hemorrhagic enterotyphlocolitis in a suckling rabbit kit due to Klebsiella oxytoca. Hemorrhagic enterotyphlocolitis in a suckling rabbit kit due to Klebsiella oxytoca.

describe cause?

Histiocytic enteritis in a laboratory rabbit associated with Lawsonia intracellularis infection. Note the marked thickening and rugose appearance of the serosal surface of the small intestine.

Jejunum of rabbit describe cause?

Jejunum from a laboratory rabbit with histiocytic enteritis due to Lawsonia intracellularis infection. Villi are shortened, lacteals are dilated, crypts are hyperplastic, and the lamina propria and submucosa are infiltrated with histiocytes and focal accumulations of lymphocytes.

Rabbit intestinal mucosa. stain? Organism?

Intestinal mucosa from a rabbit infected with Lawsonia intracellularis. Note the dense argyrophilic populations of bacteria within the apical cytoplasm of enterocytes (Warthin–Starry stain).

liver of near-term doe describe lesion cause?

New Zealand White doe that died near-term with acute listeriosis. There are pinpoint-size foci of hepatitis. The externalized kit (lower left) is intact, with no evidence of maceration

Tissue describe lesion

Focal hepatitis from a case of listeriosis in a pregnant doe. Note colonies of Gram-positive bacteria

organ cause

Pulmonary tuberculosis in a rabbit infected with Mycobacterium tuberculosis. Rabbits develop cavitary pulmonary lesions with frequent dissemination to other organs.

Tissue Causative agent

Small intestine of a wild Oryctolagus rabbit naturally infected with Mycobacterium avium spp. paratuberculosis. The lamina propria is densely infiltrated with histiocytes andmultinucleated giant cells.

Rabbit GALT histiocytes, Name of organism type of stain

Acid-fast organisms within histiocytes of the GALT of a wild rabbit naturally infected with Mycobacterium avium spp. paratuberculosis.

Describe lesion causative agent

Turbinate atrophy associated with chronic rhinitis due to Pasteurella multocida infection. Note the loss of turbinates in the affected (top) compared to the normal control rabbit (bottom).

Describe lesion

Fibrinohemorrhagic bronchopneumonia and pleuritis in a rabbit with peracute pulmonary pasteurellosis. Fibrinous exudate is present on the pleural surface.

Organ describe lesions

Pyometra in an adult doe associated with chronic Pasteurella multocida infection. There is asymmetric distention of the uterine horns, and the fallopian tubes are distended with purulent exudate (right arrow). Small abscesses are scattered on the serosa (left arrows).

Expected lesions in adult rabbits histo DDx

Systemic staphylococcosis with focal suppurative lesions can occur in adult rabbits Staphylococcal mastitis: swollen, red areas, induration of overlying skin, chronic abscess Respiratory tract: mucopurulent rhinitis, bronchopneumonia, and/or abscessation of the lung Histo: focal suppurative lesions in affected organs, w/ Gram + bacterial colonies DDX: pasteurellosis, Tyzzer’s disease, and listeriosis

Transmission Age predilection

Treponema paraluis-cuniculi (formerly T. cuniculi) is a spirochete ◦Occurs occasionally in lab rabbits, has been documented in wild rabbits in Britain ◦Seldom detected on cursory examination Venereal route is the most important means of spread, but extragenitalcontact transmission may occur Young animals may develop the disease following contact with an infected dam Young rabbits have been shown to be relatively resistant to the infection

Skin from the muzzle of a laboratory rabbit with rabbit syphilis. Describe lesion

There is dense infiltration of the dermis with mixed leukocytes, degeneration of epidermis, and serous exudation on the surface.

Stain? Organism

Rabbit syphilis lesion, depicting numerous spirochetes within the surface exudate (Warthin–Starry stain).

Describe lesion. causatuve agent

Multifocal caseation necrosis in the liver of a rabbit naturally infected with Yersinia pseudotuberculosis.

Tissue Stain Organism

Lung from a rabbit kit with pulmonary aspergillosis, illustrating fungal hyphae (methenamine silver stain).

Other organs affected?

Kidney Lung Liver Heart Cerebrum

Route of transmision in this case? Breed?

Phacoclastic uveitis and cataract formation is believed to follow transplacental infection ◦Common among dwarf rabbits, but other breeds may be affected

Stain? Tissue? Organism?

Encephalitozoon spores within renal tubular epithelium and tubular lumen of a rabbit with chronic encephalitozoonosis (Brown and Brenn stain).

Small intestine from a juvenile rabbit. Describe lesions

with acute coccidiosis. Enterocytes contain large numbers of micro- and macrogametocytes and oocysts.

Liver from a juvenile rabbit. Describe lesion causative agent

Liver from a juvenile rabbit with florid hepatic coccidiosis. In addition to the raised linear hepatic lesions, representing involved bile ducts, the gall bladder and common bile duct are dilated and contain flocculent material.

causative agent describe histo

Hepatic bile duct of a rabbit with chronic hepatic coccidiosis, featuring proliferative cholangitis, periportal fibrosis, and inflammation. Bile ductular epithelium contains large numbers of microgametocytes, macrogametocytes, and oocysts.

Describe cerebral lesion. Causative agent Describe condition

Cerebral Baylisascaris infestation in a New Zealand White rabbit. Note the focus of malacia and inflammation containing multiple cross sections of ascarid larvae with characteristic lateral alae. Larval migrans

Organ Organism

Opened cecum from a domestic rabbit with Passalurus ambiguus (pinworm) infestation.

Name of organism Describe pathogenesis of lesion

Multiple Taenia pisiformis cysticerci (arrow) within the peritoneal cavity of a rabbit. Cysticerosis ◦Intermediate host stage is known as Cysticercus pisiformis ◦Ingest eggs à larvae hatch in the small intestine and migrate to the liver and blood stream ◦Cysticerci develop in the liver for a few weeks à migrate to the peritoneal cavity, where they attach to serosal surfaces

Causative agent

New Zealand White rabbit with Cheyletiella parasitovorax infestation. Pruritus has resulted in patchy hair loss and cutaneous erythema.

Life cycle of causative agent

Psoroptes cuniculi Obligate, nonburrowing parasites that chew and pierce the epidermal layers of the external ear, evoking a marked inflammatory response Normally spends its entire life span in the external ear of the rabbit Life cycle (egg to egg) is usually completed in around 3 wks

Describe lesion

Ears of the rabbit with scabies in the previous figure, depicting severe hyperkeratosis.

Tissue Organism

Marked hyperkeratosis with numerous Sarcoptes mites embedded in the keratinized debris. Note the spongiform appearance of the keratinized epithelium due to tunneling by mites.

Risk factors

Variable morbidity, but can be high particularly in during postweaning period High mortality rate Rabbits 7–10 wks old are most often affected, but rabbits 5 wks to adults may be involved in outbreaks Dietary factors have frequently been implicated in the pathogenesis ◦Relatively uncommon prior to the feeding of high-energy commercial rations ◦Rabbits fed high-carbohydrate/ low-fiber diet have a higher incidence of the ME than those fed diets high in fiber

describe lesion Dx

massive discharge of mucin from goblet cells, with minimal or no inflammatory response ◦Colonic crypts and the lumen are distended with mucus/mucous plugs ◦Lesions are usually minimal to absent in the cecum Mucoid enteropathy

Predisposing factors

excessive grooming and hair chewing due to boredom, insufficient dietary roughage, poor gastric motility, and a sedentary lifestyle (decreased gastric motility) “Outbreaks” of trichobezoars have been seen in lab rabbits raised in cold climates, and then introduced to warm indoor housing

Associated with

chronic exfoliative dermatosis and sebaceous adenitis. Associated with autoimmune hepatitis, thymoma, and cutaneous lymphoma

Predisposing factors Associated organism

Most commonly seen in heavy, mature adults Predisposing Factors: poor sanitation, trauma from poor-quality, wire-bottom cages, and hereditary predisposition Staphylococcus aureus is the most frequent bacterium isolated from lesions

Most common location

Fracture site (or luxation) is usually the lumbosacral region (L7)

Clinical presentation

Observed in nonpregnant multiparous does Associated with persistent urogenital bleeding Necropsy: clotted blood present in the uterine lumen, w/ multiple blood-filled endometrial varices that consist of dilated, thin-walled veins Varices may rupture and bleed periodically into the uterine lumen, with subsequent hematuria

underlying cause metabolic influences

Intestinal absorption of calcium occurs in direct proportion to dietary intake. Rabbits fed high-calcium diets e.g. alfalfa that become sick can have impaired renal absorption/excretion ◦Renal calcium resorption and excretion are in proportion to dietary intake, and regulated by parathyroid hormone, calcitonin, and vitamin D When the resorptive capacity of the kidney is exceeded, calcium precipitates in the alkaline urine as calcium carbonate monohydrate, anhydrous calcium carbonate, and ammonium magnesium phosphate

Renal interstitial amyloidosis in a chronically immunized adult New Zealand White rabbit. Associated with Other organs affected

most likely in older hyperimmunized rabbits, those w/ chronic infections (pododermatitis, pyometra), or experiment. induced

Tissue Condition Cause

Condition Cause

Hypercalcemic arteriorsclerosis excessive calcium/renal overload or impairment leads to hypercalcemoia. results in metastatic mineralization of blood vessels and other tissues, including pulmonary interstitium, and kidneys (nephrocalcinosis)

Hepatic lipidosis in rabbits Mechainism Models

Rabbits are unable to increase excretion of sterols in the bile in response to high cholesterol in the diet, resulting in hypercholesterolemia, hepatic lipidosis, and icterus. NZWs fed high-cholestreol diet. hepatopathy limits long-term experiments Watanabe heritable hyperlipidemic syndrome homozygous rabbits - spontaneous

Copper toxicosis Signs of acute toxicity Histo findings - organ, stain

hemolytic anemia w/ intravasc hemolysis, splenic erythrophagocytosis, Hepatocytes and Kupffer cells contained blue-green cytoplasmic granules that stain positive w/ rhodanine stain

Age of onset Underlying cause Genetics

First few weeks of life to 3–5 months of age Primary defect = absence or underdevelopment of the outflow channels, with incomplete cleavage of the iridocorneal angles Autosomal recessive allele, with incomplete penetrance

Genetics condition

Maxillary brachygnathia (erroneously termed mandibular prognathism)à most common genetic disorder in domestic rabbits Autosomal recessive

Morphologic changes

coxofemoral subluxation, shallow acetabula, lateral patellar luxation, valgus deformity, and bowing of the tibia

Incidence

2–3 yrs à ~4%, 5–6 yrs à ~80%

Kidneys from a young rabbit. Multiple pale nodular masses are visible in the cortex, Diagnosis

Lymphoma Most common malignancy in juvenile and young adult rabbits pale kidneys w/ irregular cortical surfaces (PATHOGNOMONIC)

Most common tumor type

carcinomas