Inflammatory bowel disease (IBD) is a common feline gastrointestinal disorder that is fairly difficult to diagnose. Ultimately, an intestinal biopsy is normally necessary to definitively diagnose this condition, although sometimes even that is inconclusive.
Diagnosing Feline Inflammatory Bowel Disease
The results of routine blood tests and urinalyses are usually normal or inconclusive in cats with IBD, although these tests still are important to help the veterinarian rule out other causes of the cat’s discomfort. Many veterinarians will recommend testing the cat’s thyroid hormone levels and also testing for FeLV (feline leukemia virus infection) and FIV (feline immunodeficiency virus infection). Serum cobalamin and folate levels may also be evaluated to assess pancreatic and small intestinal function, especially in cats. Cobalamin is a cobalt-containing complex common to all members of the vitamin B12 group; folate (folic acid) is one of the vitamins of the B complex as well. Multiple fecal flotations should be done to rule out intestinal parasites as a causative or contributing factor.
Survey abdominal radiographs (x-rays) are typically normal or inconclusive in cats with IBD. Abdominal ultrasound can be used to screen for pancreatic disease, isolated gastrointestinal lesions (masses, ulcers) and thickening of the intestinal lining. A dietary trial should also be performed to rule out food allergies. If all of these diagnostic tools do not point to another primary disorder, IBD will move to the top of the list as the primary suspect.
To make a definitive diagnosis of inflammatory bowel disease, biopsies usually are necessary (although even these may not be 100% conclusive). Tissue samples can be collected surgically or endoscopically. Surgical exploration is the only way to collect full-thickness intestinal samples. Endoscopic samples should be taken from multiple areas of the intestinal lining. Both of these procedures are performed under general anesthesia. The tissue samples will be sent to the laboratory for microscopic examination by a veterinary pathologist, who will look for the hallmarks of exuberant inflammation that are present with IBD.
In some cases, the attending veterinarian may choose to treat IBD without taking biopsies, especially if all other likely causes of the cat’s clinical signs have been ruled out. If the cat’s condition improves with symptomatic treatment, the presumptive diagnosis of IBD is assumed to be correct.