Diarrhea is among the most common complaints veterinarians encounter in their feline patients. A common cause of intermittent chronic diarrhea (with or without vomiting), however, is often overlooked and under-diagnosed; its inflammatory bowel disease (IBD).
Actually, IBD isnt really a disease itself but a group of chronic gastrointestinal disorders that we often see, primarily in middle-aged and older cats, says Bruce Kornreich, DVM, of the Cornell University College of Veterinary Medicine. IBD occurs when inflammatory cells invade the lining (or mucosa) of the stomach or intestines.
Diagnosis and cause
The specific kinds of inflammatory cells found in the tissue determine the type of IBD diagnosed. The most common type in cats is lymphocytic-plasmacytic enterocolitis, which means that the cells found in the intestinal wall are white blood cells (lymphocytes) and cells that produce antibodies (plasma cells) and that the inflammation is present in the large and small intestines (enterocolitis). Other kinds of inflammatory cells cause the less common types of IBD in cats, such as eosinophilic, neutrophilic, and granulomatous IBD. When the inflammation is strictly in the small intestines, the condition is called enteritis; if it is only in the large intestine, it is called colitis; when it is only in the stomach, its called gastritis.
Although the cause of IBD has not been specifically identified, researchers believe that it can be caused by various factors. Inflammatory cells probably get into the intestinal lining as a result of an injury, defect, infection, or when the immune system launches an attack against parasites, particular foods, bacteria, fungi, or a cancer in the area.
Frequent diarrhea and vomiting can dehydrate a cat quickly and dehydration can be very serious, so cats with chronic gastrointestinal distress should see a veterinarian promptly, says Kornreich. He says the veterinarian will need to perform a host of diagnostic tests to rule out conditions such as intestinal parasites, hyperthyroidism, liver disease, infection with feline leukemia virus (FeLV) or other viruses, heartworm disease, or pancreatitis. Once these disorders are ruled out, the veterinarian may recommend a combination of other diagnostic tests, including an abdominal ultrasound examination and an endoscopic examination using a flexible instrument that can be passed into the gastrointestinal tract (and through which biopsies of the intestinal lining can be taken).
Treating IBD usually involves a combination of dietary changes and medication. Sometimes changing the protein in the diet to a protein the cat has never eaten before (i.e., a hypoallergenic diet) may be helpful. These diets are often duck- or venison-based and may require six to eight weeks for an improvement to be obvious. In cats with inflammatory colitis, foods containing more dietary fiber (such as Hills r/d) may help. Feeding a highly digestible diet may benefit patients that do not respond to hypoallergenic or high fiber diets.
The most common medication prescribed for cats with IBD is the corticosteroid prednisone, an anti-inflammatory and immunosuppressive medication. If effective, some cats may need the medication for the rest of their lives. An antibacterial medication, such as metronidazole or tylosin, sometimes helps, especially when dietary changes and corticosteroid therapy have failed to relieve the signs. The veterinarian also may suggest an immunosuppressive drug, such as azathioprine or cyclophosphamide, to reduce the dose of steroid being used or to relieve symptoms when other therapies havent worked. An anti-diarrhea or anti-vomiting medication may also be useful. On the forefront are medications now being used for IBD in humans – such as cyclosporine, sodium cromoglycate, and clonidine – that may prove useful in cats in the future.
Although we dont know the underlying cause of IBD, researchers suspect a variety of factors may play a role, such as genetics, diet, nutrition, infectious substances, and immune system abnormalities. Nor do researchers know how to reliably cure the disease, says Kornreich. Often, veterinarians try a variety of strategies to find one that can control the disease while minimizing the side effects of therapy. Clinical signs may still continue to flare up from time to time, however. In most cases, IBD is not cured but can be managed so that the cats (and his human companions) quality of life is improved.