Perianal Fistuala,  –  Just the name of it alone sounds painful.  You may or may not have heard the term before.  It can also be known as furuncuosis and is a serious medical condition that most commonly affects German Shepherd dogs, but can also occur in other purebred or mixed breed dogs.  A fistula is an abnormal connection that forms between two tissues, organs, or vessels that normally do not connect. In affected dogs, the condition is usually associated with an infection in the perianal region or right under the tail.

Early on there may be few clinical signs and the condition may go unnoticed. Some cases are discovered during a routine wellness examination by your veterinarian.  Some possible signs may be straining during defecation, and blood surrounding the feces. A decreased appetite (anorexia) is common in dogs with perianal fistulas. The dog may also lick excessively at its tail and rectal region. Some dogs will be reluctant to sit, some may not wag their tail normally, and some may become aggressive if the tail or hindquarters are touched.

The cause is not fully understood, but immune-mediated disease and anatomic factors have been implicated.  A genetic predisposition based on breed has been proposed, but not proven.  Impaction or infection of the anal sacs (anal glands) can complicate this disease process further.

The condition can be treated by your veterinarian several ways.  Medical management with immunosuppressant and immune-modulatory drugs such as oral cyclosporine (Atopica), and topical tacrolimus are needed for prolonged periods of time.  Diet may also be a factor and feeding a hypo-allergenic prescription dog food may be helpful.  Frequently the improvement is not permanent and chronic treatment is needed.  Increasing ventilation of the perianal region by clipping the area, particularly in long-coated dogs, combined with careful bathing and cleaning is a useful palliative measure.

Surgery may be needed to debride or remove as much infected tissue as possible, but medical management is always needed.  In some cases tail amputation may be needed to eliminate the moist environment caused by dogs that carry their tails low and close against their rectum.

The best thing to do is ask your veterinarian.  He or she will be able to diagnose the issue and create a treatment plan that is right for your dog.