JPC SYSTEMIC PATHOLOGY
SIGNALMENT (JPC # 2316884): A young New Zealand white rabbit
HISTORY: The animal was depressed, displayed a crouched stance, grinding of the teeth, thin conformation, bloated abdomen and had diarrhea.
HISTOPATHOLOGIC DESCRIPTION: Colon: The colon is markedly distended and contains abundant amphophilic flocculent material (mucus) within the lumen. The mucosal epithelium is diffusely thickened by an increase in thickness of crypts which contain variable amounts of mucus are tightly packed, tortuous, and lined by numerous hypertrophied goblet cells (goblet cell hyperplasia).
MORPHOLOGIC DIAGNOSIS: Colon: Goblet cell hyperplasia, diffuse, severe, with luminal distension by abundant mucus accumulation, New Zealand white rabbit, lagomorph.
CONDITION: Mucoid enteropathy (ME)
- Major disease of domestic rabbits, but it is not primary disease
- Gastric bloat, mucous discharge, and cecal impaction are cardinal features, but are non-specific responses to unknown deleterious factors
- Most affected are weanling rabbits between 7-10 weeks of age
- Toxin-induced secretory disease occurring secondary to constipation and impaction
- Morbidity and mortality can be high
- Important cause of mortality in rabbit production and research facilities
- Dysautonomia has been documented in rabbitries affected with this condition
- Often associated high carbohydrate/low fiber diet
- Cause is unknown, many proposed theories
- May precede or be associated with viral and/or bacterial intestinal conditions
- Sterile cecal contents from affected rabbits produce goblet cell hyperplasia in other rabbits, confirming the presence of an unknown secretagogue (possible endogenous substance or toxin)
- Higher incidence with high carbohydrate/low fiber diet: Low dietary fiber > ↓cecal acetate > cecal acidification > changes in microflora / ↑ harmful opportunistic bacteria, decreased ciliated protozoa, metachromatic bacilli (dysbiosis) > bacterial toxins released (secretagogues) > stimulate intestinal goblet cell hyperplasia
- Cardinal features include gastric bloat, mucous discharge and cecal impaction; these are considered non-specific responses of the rabbit intestine to many causes
TYPICAL CLINICAL FINDINGS:
- Acute, fatal cases follow a 2-4 day course
- Bruxism, anorexia, lethargy, crouched stance, diarrhea, succession splash, cecal impaction, abundant clear gelatinous mucus in colon
- Cecum impaction and colonic mucous accumulation, 7-14 days post onset of syndrome
- Elevated hematocrit, RBC count, hemoglobin, and BUN
- Decreased sodium, chloride, and phosphorous
- Stress induced heterophilia and hyperglycemia
TYPICAL GROSS FINDINGS:
- Stomach is often distended with gas and fluid
- Colon distended with clear, gelatinous mucus
- Cecum often compacted with dry content
- Small intestines generally contain watery, bile-stained contents; jejunum may be distended
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Goblet cell hyperplasia may be present throughout the gastrointestinal tract and is most severe and consistent in the ileum and colon; minimal to absent lesions in cecum
- Marked mucin discharge into intestine lumen with mucin distended crypts
- The absence of inflammation is characteristic
ADDITIONAL DIAGNOSTIC TESTS: Diagnosis is based on clinical signs and characteristic gross and microscopic features
COMPARATIVE PATHOLOGY: ME has similarities to human cystic fibrosis, a disease of defective electrolyte transport that causes excessive mucus production by intestines, pancreatic and bile ducts, and respiratory epithelium
- Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Blackwell Publishing; 2016:306-307.
- Haligur M, Ozmen O, Demir N. Pathological and ultrastructural studies on mucoid enteropathy in New Zealand rabbits. JEPM. 2009; 18:224-228.
- Hotchkiss CE, Merritt AM. Mucus secretagogue activity in cecal contents of rabbits with mucoid enteropathy. Lab Anim Sci.1996; 46:179-186.