| Diarrhea Part 4 |
| Routine Hemogram and Blood Chesistry Anemia may be present in longstanding cases and is usually ascribed to chronic blood loss. Changes in the white count are uncommon but a lymphopenia is present in about 50% of dogs with lymphangiectasia. Eosinophilia, unexplained by the presence of parasite infection, may suggest eosinophilic enteritis. Changes in blood chemistires are uncommon but if present may help to differentiate between primary gastrointestinal disorders and systemic or metabolic disease. Mild elevations in liver enzyme activity (AP and ALT) are quite common in inflammatory bowel disease, while hypoproteinemia may be observed in some dogs with protein losing enteropathy (PLE). Diagnostic Studies in Canine Small Intestinal Disease: Rule out EPI (TLI test), Radiographs and Ultrasound, Folate and cobalamin, Biopsy, Response to Rational Therapy. The Fecal Examination A complete fecal examination should always include both macroscopic and microscopic examination. It is often helpful to watch the animal defecate since signs of small or large bowel diarrhea that may be confused by the history may be readily apparent when the veterinarian observes the patient directly. Macrosopic examination of a fresh fecal sample is essential for assessment of bulk, color and consistency, as well as for the detection of blood and mucus. Microscopic examination of the feces by both direct (smear) and indirect (flotation) techniques for evidence of parasitic infection is mandatory in every dog with diarrheal disease. Special tests may be needed to eliminate infection with Giardia. Bacteriological culture of the feces is unrewarding, but should be considered if infection with Salmonella sp. or Campylobacter sp. is suspected. A test for Clostridium perfringens toxin should be routine in patients with signs of large bowel diarrhea. A direct smear may also identify spores of C. perfringens. Initial Approach After infectious and metabolic causes have been ruled out, it may be appropriate to simply change the patient's diet to a highly digestible and single protein source product. Treatment with a broad spectrum anthelmintic such as fenbendazole is also appropreate as is a trial course of an antibiotic such as metronidazole or tylosin. Treatment with sulfasalizine (Salazopyrin) may be useful in patients with large bowel diarrhea. Small Bowel Diarrhea After the above studies are concluded it should be possible to decide whether signs of small or large bowel diarrhea predominate. The TLI Test Measurement of the concentration of trypsinogen in the serum is the easiest and most reliable test for the diagnosis of exocrine pancreatic insuffieciency (EPI). The normal range is between 5 and 35ug/L. Levels below the reference range are compatible with a diagnosis of EPI. Abdominal Imaging Radiographs are usually interpreted as normal in most dogs with chronic diarrhea. In some patients however, they may reveal visceral displacement, an unsuspected foreign body or a mass. Survey thoracic radiographs should also be made as part of the initial data base if circumstances permit. Part 5 |