Summary
Inflammatory bowel disease (IBD) is a relatively common chronic disease that affects the intestines of both dogs and cats. In this poorly understood disease (the cause of which is currently unknown), the lining of the intestines (particularly of the colon) become inflamed through a process mediated by the patient's immune system.
Several specific types of cells may become inflamed through this process. The most common version of IBD is called lymphocytic-plasmocytic. The eosinophilic type involves the white blood cell known as the eosinophil and it's distinguished by its severity and recalcitrance in the face of treatment. The rarest form involves the class of white blood cells called granulocytes. Luckily, it's rare, as it's notoriously difficult to treat.
One theory posits that the intestines of these animals are more permeable to bacteria and foods or are otherwise immunocompromised. In other words, the immune system has broken down at the level of the intestinal lining. Another offers that an appropriately-functioning immune system is hypersensitive to "invaders" in the form of food ingredients and/or normal bacteria.
In either case, the upshot is the same: Inflammation results, bacterial overgrowth occurs, and the animal is unable to properly digest foods and absorb nutrients.
Genetic factors are believed to play a significant role in IBD.
Symptoms and Identification
Clinical signs of IBD are primarily associated with diarrhea, though some pets may also suffer bouts of vomiting and weight loss or apparent unthriftiness. For IBD, signs typically come and go, appearing to go into a spontaneous remission before returning with a vengeance.
The idea behind the diagnosis of IBD is that veterinarians attempt to exclude parasitism, dietary sensitivity (in the form of a true food allergy or dietary intolerance), infectious diseases, digestive tract cancers (like lymphosarcoma) and other systemic diseases that may cause the same clinical signs. IBS (irritable bowel syndrome) is another possible diagnosis for the same symptoms. It's generally related to stress, however, and it's easiest to rule out with biopsies and a history of stress-related episodes of diarrhea.
All cases of suspected IBD should ideally be tested via biopsy of the intestinal tissue. This is best done through endoscopy and/or colonoscopy. Alternatively, provocative treatment with drugs to kill excess intestinal bacteria and parasites may be attempted. Food trials to determine whether true food allergies or dietary intolerance are at play is also deemed an acceptable tack by way of excluding these diagnoses.
Affected Breeds
In cats, middle-aged to older purebred cats seem predisposed, though no specific breed predilection has been definitively established. In dogs, German Shepherds, Yorkshire Terriers and Cocker Spaniels may be predisposed, though there is no definitive evidence to the fact.
Treatment
Treatment of IBD is typically one of trial and error and it tends to be three-fold:
Dietary management: While this is the first line of attack in handling IBD, it's seldom the case that diet changes can manage the disease alone. Nonetheless, administering foods with a reduced ability to stimulate the immune system is a fundamental approach to the disease. Administering dietary supplements in the form of specific fatty acids may also help these patients.
Immune system-affecting drugs: Drugs like corticosteroids (such as prednisone) and other immunomodulating drugs (tylosin and cyclosporine) are often prescribed to help interfere with the immune system's ability to cause inflammation.
Antibiotics: Handling the overgrowth of unwanted quantities of bacteria is typically required intermittently over the course of IBD treatment.
Veterinary Cost
The cost of diagnosis can be high, especially because many tests must be undertaken to rule out other diseases, and also because the cost of endoscopy and/or colonoscopy can be quite high ($500 to $1,000 or more, depending on the facility and geographic location).
The cost of treatment, however, is considered relatively manageable, primarily because the drugs used to treat this disease are typically relatively inexpensive. Over a long lifetime, however, the costs can easily run into the thousands of dollars.
Prevention
There is no known way to prevent IBD. However, removing affected animals from the genetic pool is considered a basic line of defense.
References
Guilford WG: Idiopathic inflammatory bowel diseases. In Guilford WG, et al eds: Strombeck's Small Animal Gastroenterology. Philadelphia: WB Saunders, 1996:451-486.
Wilcox B. Endoscopic biopsy interpretation in canine or feline enterocolitis. Semin Vet Med Surg 1992; 7:162-171.
Jergens AE. Inflammatory bowel disease: Current perspectives. Vet Clin North Am Small Anim Pract 1999; 29:501-521.
Jergens AE, Andreasen CB, Hagemoser WA, et al. Cytologic examination of exfoliative specimens obtained during endoscopy for diagnosis of gastrointestinal tract disease in dogs ans cats. J Am Vet Med Assoc 1998; 213:1755-1759.