The first step in working up chronic diarrhea in a cat is localizing it to small bowel, large bowel, or a combination using clinical sign pattern recognition. Chronic disease is defined as signs present for more than 3 weeks or intermittently recurring for more than 3 weeks.Veterinary Clin…
Small bowel diarrhea is characterized by large volume, weight loss, and vomiting, while large bowel diarrhea is characterized by increased frequency, mucus, tenesmus, and dyschezia. Small bowel diarrhea carries a higher grade for weight loss and vomiting, whereas large bowel diarrhea carries a higher grade for mucus and tenesmus; general condition is more affected with small bowel disease.Veterinary Clin… Diarrhea is a rare presenting sign in feline pancreatitis, so small bowel diarrhea with concurrent vomiting and weight loss should direct the workup toward primary intestinal disease rather than pancreatic disease.Journal of Feli…
Once small bowel localization is established, the differential diagnosis is dominated by chronic enteritis (inflammatory bowel disease/chronic inflammatory enteropathy) and intestinal lymphoma. In cats with clinical signs of chronic small bowel disease and ultrasonographic small bowel thickening, chronic small bowel disease was diagnosed in 96% of cases, with chronic enteritis (n = 150) and intestinal lymphoma (n = 124) as the two most common diagnoses.Journal of the… These two conditions are clinically indistinguishable — both present with weight loss, decreased appetite, vomiting, and diarrhea.Journal of Vete…+1
The minimum database should include a complete blood count, serum biochemistry, urinalysis, total thyroxine (in cats over 7 years), fecal flotation, and abdominal ultrasonography. Fecal bacterial culture and PCR panels for enteropathogenic bacteria have low diagnostic value because putative enteropathogenic bacteria are detected at similar rates in cats with and without diarrhea, and diarrhea is not significantly associated with enteropathogenic infections in cats.Journal of Vete… Ultrasonographic small bowel thickening supports the diagnosis of chronic small bowel disease but cannot differentiate chronic enteritis from intestinal lymphoma.Journal of the…
Tissue biopsy is required to distinguish inflammatory bowel disease from intestinal lymphoma — ultrasonography and clinicopathologic testing alone are insufficient for this differentiation. Full-thickness biopsy specimens obtained from at least 3 small intestinal locations via laparotomy are useful for this distinction.Journal of the… Histopathology alone is also insufficient in many cases: 15.6% to 26% of cases initially diagnosed as inflammatory bowel disease based on histopathology are reclassified as lymphoma after immunohistochemistry (IHC), and 4% to 53% are reclassified after clonality testing (polymerase chain reaction for antigen receptor rearrangements, PARR) with or without IHC.Journal of Vete… IHC and PARR should therefore be performed when histopathologic findings are ambiguous.Journal of Feli…
Both upper small intestinal (duodenal) and lower small intestinal (ileal) biopsy samples should be collected, as 44% of lymphoma cases were diagnosed only by ileal and not duodenal biopsy evaluation.Journal of Vete… Performing both upper and lower gastrointestinal endoscopy increases anesthesia time, patient risk, and procedure costs, but the diagnostic yield justifies this approach.Journal of Vete…
In cats in endemic regions, Leishmania spp. infection must be included in the differential for chronic small bowel diarrhea, particularly when nonregenerative anemia and hypergammaglobulinemia are present — hypergammaglobulinemia is present in 87.5% of affected cats.Journal of Vete… Immunosuppressive treatment should not be initiated before biopsy in these patients, as it can be harmful if leishmaniosis is the underlying cause of gastrointestinal inflammation.Journal of Vete…
| Feature | Small Bowel Diarrhea | Large Bowel Diarrhea |
|---|---|---|
| Volume | High | Lower |
| Mucus | Absent | Present |
| Frequency | Mildly increased | Markedly increased |
| Tenesmus | Absent | Present |
| Dyschezia | Absent | May be present |
| Weight loss | Prominent | Less prominent |
| Vomiting | Common | Less common |
| General condition | More affected | Less affected |
Veterinary Clin…
Would you like guidance on how to differentiate inflammatory bowel disease from small cell lymphoma once biopsy results — including histopathology, IHC, and PARR — are in hand?