Page 770 - Problem-Based Feline Medicine

34. The cat with signs of large bowel

diarrhea (acute and chronic)

Debra L Zoran

KEY SIGNS
● Soft, mucoid, formed to semi-formed feces.
● + Fresh blood or straining.

MECHANISM?
● Large bowel diarrhea is induced by increased secretion of water and electrolytes by
colonic epithelial cells, overload of substrate (from small bowel) or by altered motility
(e.g. decreased motility, loss of segmentation).
● Increased fermentable substrate (e.g. carbohydrates such as soluble fibers, lactulose, etc.)
may increase fecal water and create a softer fecal mass.
Signs of large bowel diarrhea:
● Soft, mucoid, formed to semi-formed feces.
● Hematochezia.
● Straining to defecate.
● Increased urgency to defecate.
● Small volume of fecal material expelled.
● Vomiting or weight loss not typically observed.

WHERE?
● Acute, large bowel diarrhea is uncommon in cats and is less likely to be associated with
parasites (e.g. whipworms) or clostridial enterocolitis compared to dogs.
● Chronic or recurrent large bowel diarrhea may be caused by local (e.g. large bowel) or sys-
temic disease, and thus a thorough evaluation that includes a minimum database, imaging
studies (radiographs, ultrasound, etc.), or endoscopy with collection of biopsies is required to
determine the cause.
● Irritant colitis secondary to ingestion of hair, feathers or other foreign material is a com-
mon cause of acute large bowel diarrhea.
● Cats usually do not lose weight or have vomiting episodes in association with large
bowel diarrhea unless a systemic disease is the cause of the problem.

WHAT?
● The most common causes of large bowel diarrhea are inflammatory (inflammatory
bowel disease), neoplasia, metabolic diseases (hyperthyroidism) and mechanical (hair,
feathers or bone-induced colitis).
● Food intolerance may be a common cause of colitis, but is not well documented in cats.
● Clostridial enterocolitis is the most common infectious cause of colitis in adult cats, but
the incidence in cats is low compared to other causes of large bowel diarrhea.

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