Canine anal furunculosis (perianal fistula) is a chronic condition that primarily affects middle-aged dogs. The definitive cause has not been identified, but many theories have been proposed. Currently, an immune-mediated process is thought to be involved. Immunosuppressive-immunomodulating therapy may be helpful in managing the disease. Glucocorticoids, cyclosporine, and azathioprine have all been proposed as possible therapies. Clients should be informed of the benefits and risks of glucocorticoids before using them. These agents can be used in combination with azathioprine or metronidazole. Cyclosporine appears to be the most effective medical treatment to date. After resolution of clinical signs, the dose can be reduced. Another approach that has been useful in some dogs has been dietary therapy, which in the authors' opinion may influence the course of disease. They have managed a few cases with antibiotics and a restrictive trial diet. Since secondary infection is almost always present, antibiotic therapy is recommended. The perianal regions should be kept clean and dry. Some dogs require various forms of surgery as adjunctive therapy. New therapies used for people with Crohn's disease may one day have utility in these patients.

COMMENTARY: Canine anal furunculosis is a frustrating disease for which management has changed dramatically through use of such immunomodulating agents as cyclospor-ine. This article is a good review of the disease. Included is a helpful comparative chart of various studies using cyclosporine for its treatment.

Managing anal furunculosis in dogs. Patterson AP, Campbell KL. COMPEND CONTIN EDUC PRACT VET 27:339-354, 2005.