Diagnosis
Diagnosis is based on physical examination and history. Sedation may be necessary to perform a thorough examination since the condition can be very painful. Biopsy samples will confirm the diagnosis.
Causes
While the precise cause of the disease is unclear, some German Shepherds seem to be unable to resist even superficial infections which may arise in the skin. This may be the result of an ineffective immune response resulting in predisposition to the development of skin infections as a persistent problem. Additionally, the conformation of the German Shepherd allows for the broad base of the tail to remain in almost continual contact with the anus, thereby spreading a thin film of feces over the perianal region. Hence this is the site which is affected most frequently. Recent evidence, however, points to an immune-mediated process as the underlying cause of this disease.
The anal sacs (scent glands) are usually involved in the disease process and are removed as part of the initial treatment. It should also be emphasized that a dog's predisposition to the development of Perianal Fistulas is lifelong. Relapses, although uncommon, may sometimes occur even after apparent care.
Treatment
In the past, treatment for perianal fistulas included surgical ablation (removal of the fistula) or deroofing (removal of the skin covering each tract). In general, surgery has been replaced by the use of immunosuppressive drugs. The response to cyclosporine, prednisone, and tacrolimus has been encouraging. Cyclosporine is generally considered to be the drug of choice and is typically used on a 16-week course of treatment. Surgery, once widely used, is presently reserved for cases that involve the anal sacs or for selective cases that do not respond to medical management.
Prognosis
Regardless of the treatment used, the earlier the condition is diagnosed and treated, the better the outcome. In most cases the prognosis is guarded to fair, understanding that recurrence is common. In more severe cases, and those involving surgery, fecal incontinence is a major concern.
