Those Troublesome Chronic Diarrhea Cases

Chronic diarrhea is a common complaint, and the potential etiologies are extensive. Parasites, dietary intolerances, metabolic disease, pancreatic disease, bacterial causes, and inflammatory bowel disease are but a few etiologies of chronic diarrhea. Inflammatory bowel disease (IBD) is a common condition diagnosed in dogs and cats; however, it is not a specific disease but rather a term that describes animals having gastrointestinal (GI) signs with histologic evidence of inflammation within the intestine. IBD does not however describe the etiology, nor does the extent of inflammatory cells parallel the severity of clinical signs. Before beginning extensive diagnostics or obtaining an intestinal biopsy specimen from a patient with chronic diarrhea, there are a few diagnostic tests or trial therapies to consider. Obviously the course of action is predicated in part on a good clinical evaluation and based on the severity of the clinical disease. Every patient with chronic GI signs should have a thorough history, physical examination, complete blood count, biochemical profile, urinalysis, and fecal examination. In many cases, this initial evaluation will determine if the etiology of the diarrhea is primary GI disease or secondary to other systemic or metabolic disease or if the diarrhea is predominately of small bowel or large bowel origin. For example, Addison’s disease, liver disease, and renal disease can all be associated with secondary GI involvement. If the initial workup fails to provide a clue as to the etiology, then begin a specific GI evaluation. The fecal examination should include standard fecal flotation, wet mount preparation, and stained cytology. A stained Diff-Quick cytology may reveal such things as neutrophils, eosinophils, fungal organisms, or clostridial spores and may provide clues about the etiology. This is also the time to classify the patient based on the severity of disease: minimal signs and debilitation or those cases having severe disease obviously requiring an in-depth GI workup. For the animal with relatively mild diarrhea without weight loss or debilitation, I prefer to use trial therapy as part of the clinical evaluation. Trial therapy involves antiparasitic therapy, dietary food trials, and antibiotic therapy. If these trial therapies fail to resolve the diarrhea, further GI evaluation is indicated. Additional diagnostic testing may include imaging studies (ultrasonography is preferred as barium studies are rarely helpful), serology trypsin-like immunoreactivity, folate, cobalamin), and endoscopy or surgery for intestinal biopsies.