Update on managing IBD in dogs (Proceedings)
It is important that the clinician formulate a treatment protocol based on a correlation of clinical course, laboratory and gross findings, and histologic findings rather than relying on histologic changes alone. Although treatment principles for cats and dogs with IBD are similar, drug selection and dosage regimens vary between these two species in some situations.
Specific treatment recommendations for dogs with inflammatory bowel disease (IBD) are as follows. Corticosteroids are the initial treatment of choice for lymphocytic-plasmacytic and eosinophilic enteritis in most cases. Mild to moderate cases (as determined by clinical signs, normal protein levels, and degree of inflammatory cell infiltrate on biopsy) often respond to prednisone at a dose of 0.25 to 0.75 mg/lb divided twice daily for two to four weeks followed by a gradual decrease in 50% increments at two-week intervals. Alternate day or every third day treatment can often be reached by two to three months. Occasionally treatment can be discontinued altogether by three to six months.
Moderate to severe cases and any case in which the total protein is less than 5.5 g/dl should be treated more aggressively using an initial prednisone dose of 1 mg/lb per day for two to four weeks before an attempt is made to decrease the dose. Dogs in this category often require long-term therapy (months to years) on an every other day or every third day basis to maintain remission. Use of combination drug therapy (prednisone and metronidazole) in these cases at the outset is recommended in order to improve chances of controlling clinical signs more quickly and to prevent progression of the disease.If significantly bothersome side effects are caused by prednisone (e.g., severe polyuria/polydipsia, panting, lethargy, etc.), oral dexamethasone can be used instead. In some dogs dexamethasone is much better tolerated and side effects are minimal or nonexistent. If prednisone side effects are judged to be severe it is generally discontinued for 12 to 36 hours in order to allow for adequate metabolism and clearance. Prednisone may then be reintroduced at 25 to 50 percent of the previous dose or alternatively dexamethasone can be instituted at a conservative level (0.005 to 0.01 mg/lb/day orally).
Budesonide is a new and recently approved corticosteroid for use in humans. Budesonide is a glucocorticoid that also represents a new alternative for management of IBD in dogs and cats, especially in severe cases that have proven to be refractory to prednisolone, metronidazole, azathioprine, and dietary management; or that are intolerant of the corticosteroids discussed above. It is one of a group of novel corticosteroids that have been in development for use in humans in an attempt to make available alternative preparations that will help limit toxicity associated with corticosteroid use. Others include fluticasone propionate, tixocortol pivalate, and beclomethasone dipropionate.
Budesonide undergoes high first pass metabolism in the liver and 90% is converted into metabolites with low corticosteroid activity. It has minimal systemic availability. The potential for typical corticosteroid side effects is significantly reduced as a result of decreased bioavailability and the resulting limited systemic exposure, which makes this a particularly attractive drug for use in humans and animals that are poorly tolerant of other corticosteroids. Budesonide also has a high receptor-binding affinity in the mucosa. It has been referred to as a "locally acting" corticosteroid.
Therapeutic results with budesonide have been promising in humans with Crohn's disease, collagenous colitis and lymphocytic colitis, ulcerative colitis, either when administered as a retention enema or in oral form, and primary biliary cirrhosis. Budesonide has been used by some veterinary clinicians in recent years to treat IBD in dogs and cats. Dose recommendations vary. In humans, a range of 6 mg to 9 mg per day has been used during initial therapy. The following general recommendations have been made for dogs and cats. In general, budesonide is administered to cats and small dogs at 1 mg administered once per day. It has been used at higher doses (3 mg per small dog or cat per day), but the lower dose is frequently effective. Large dogs receive 3 mg twice daily initially, and the dose is later tapered to 3 mg once daily, and then to alternate day administration for longer term use.
When a patient is either poorly responsive to corticosteroids when used as outlined above, or if there is poor tolerance, the next best options are to try either budesonide or cyclosporine. Cyclosporine is described further below. Budesonide can be used in combination with other drugs. Potential adverse effects include PU/PD, when budesonide is used at the high end of the dose range, and GI ulceration. These reactions have been observed in some human patients. These problems would be more likely to occur in dogs than in cats. It appears to be very safe when used at the levels listed above.