Inflammatory bowel disease (IBD) is thought to result from inappropriate and ongoing activation of the mucosal immune system driven by the presence of normal luminal flora. This aberrant response is most likely facilitated by defects in both the barrier function of the intestinal epithelium and the mucosal immune system. There are many human and animal studies that provide evidence that there is a genetically determined susceptibility to IBD. However, the development of this disease depends on additional factors. Luminal bacterial flora is a requisite and perhaps the central factor in the development of IBD. The end result is the sustained activation of mucosal immune responses.

Treatment of inflammatory bowel disease must begin with an accurate diagnosis. The diagnosis depends on the aggregate constellation of the appropriate clinical history, physical findings, laboratory test results, and endoscopic and histologic features. Long term management must be multidimensional and is governed by the type, distribution, and grade of inflammatory bowel disease.

1) Diet- There are many opinions on what is the best diet for inflammatory bowel disease. Typically the choices boil down to whether an easy-to-digest limited GI diet or a novel protein diet is used. Additionally, some presentations of IBD (particularly those with a significant lower bowel component) require the addition of extra fiber to the diet. As a rule of thumb, I tend to begin therapy with limited GI prescription diets in cats and recipe diets in dogs. The GI diets I use in cats include: Eukanuba Low Residue Diet, Purina CNM-EN diet, and I/D. In dogs, most are offered a bland recipe diet of low-fat, small curd cottage cheese and boiled white rice (not instant) mixed 1:2 or 1:3. At the end of three weeks, I often have petowners slowly introduce a limited GI prescription diet to their dog. The GI diets I use in dogs include: Purina CNM-EN diet, Eukanuba Low Residue Diet, I/D, and Waltham intestinal diet. I will use a novel protein diet (IVD or Eukanuba) if the inflammatory change in the biopsies includes significant numbers of eosinophils, if the patient is pruritic, or if the limited GI diet trials fail. There are many choices of novel protein diets available for cats and dogs. Finally, Finally, I have had some success in using elemental diets (eg., ultra- Z/D), which modulates the antigenic load either directly or indirectly (through altered bacterial flora).

2) Glucocorticoid therapy- Administration of immunosuppressive doses of prednisone, gradually tapered, is effective in treating inflammatory bowel disease. I use prednisolone frequently in cats, rarely in dogs. Dogs have significantly more trouble with side effects from glucocorticoid therapy than cats, but there is a significant risk of developing diabetes mellitus in cats being treated with longterm daily glucocorticoids. An alternative glucocorticoid therapy is the

3) Antibiotic therapy- Administration of antibiotics are a common component of therapy for inflammatory bowel disease (and, obviously, in infectious gastrointestinal diseases that are not included under the nomer of IBD nor under discussion here). Metronidazole is administered at 7-15 mg/kg BID to TID and Tylan is administered at ~¼ tsp of the commercial powder product per 40-50 kg dog BID or compounded into capsules and given at 7-11mg/kg BID for smaller patients or larger patients that do not like the taste of the powder product when mixed into their diet. The exact modes of action of these antibiotics is not completely known, however, their effect on the intestinal bacterial flora is the primary action. Metronidazole, has additionally been purported to have immunomodulatory actions which may alter immune responses within the digestive tract and liver. Other antibiotics that have been used in the treatment of IBD in people include ciprofloxacin and clarithromycin.

4) Sulfasalazine and other 5-aminosalicylate-based compounds- These drugs act by blocking the production of prostaglandins and leukotrienes, inhibiting bacterial peptide-induced neutrophil chemotaxis and adenosine-induced secretion, and scavenging reactive oxygen radicals. Sulfasalazine acts specifically in the colon after the 5-ASA component (mesalamine) is cleaved from the sulfapyridine component of the drug in the colon. Other similar agents like olsalazine consist of two mesalamine molecules bound together which become active in the colon after cleavage from each other. Finally, there are also 5-ASA compounds that can be administered directly to the colon and anorectal area by enema. I use sulfasalazine in dogs routinely when the presentation of their inflammatory bowel disease is primarily lower bowel. I administer 10-15 mg/kg PO BID for 10 days, repeating the 10-day course as needed for flare-ups of colitis signs occurring thereafter. I also use sulfasalazine routinely in cats when the presentation of their inflammatory bowel disease is primarily lower bowel. I administer 4.5mg/kg PO