Perianal fistulas are caused by inflammation, ulceration, and draining tracts around the anus. They can originate from an infected hair follicle around the anus with the warm, moist environment this region of the body provides, supporting the infection. The underlying cause is thought to be immune-related disease. Eventually a tract forms creating a draining sore. Perianal fistulas may be associated with infected and inflamed the anal sacs.
Affected Breeds

Perianal fistulas are most commonly seen in German Shepherds between the ages of 5 and 14 years. Irish Setters may also have a predisposition. It is more common for males to be diagnosed with perianal fistulas than females. Intact dogs are at an even higher risk. Perianal fistulas are seen rarely in cats.

Symptoms may include the following:

Anal discomfort
Perianal discharge
Weight loss
Decreased appetite
Thinning haircoat

Anal discomfort, licking, and scooting may be observed in your pet before a fistula is present.


Diagnosis is by examination of the perianal area. It often must be done under sedation due to severe pain at the site. This will vary with each patient. The area may be shaved and a rectal exam performed to identify the presence of a fistula. Fistulas are usually external but can also be formed internally, which carries a more grave prognosis.


Perianal fistulas are more easily treated in their earlier stages and require less radical procedures. The severity of your pet’s fistulas along with the best treatment options will be discussed at your appointment.

Fistulas can be treated and managed medically with the use of antibiotics, cyclosporine, and regular cleanings. Medical treatment lasts for several months, but with consistency your pet could improve. For those fistulas that cannot be treated solely through medical means, surgery may be warranted. If the anal sacs are associated with the fistulas, an anal sacculectomy may be performed to remove the anal sacs. At this point medical treatment may be prescribed by the surgeon to treat the remaining infection. Surgery can be more dramatic in severe cases with removal of diseased skin and surrounding tissue or tail amputation. The most common surgical approach is bilateral anal sacculectomy with fistulectomies.

Postoperative Care

Perianal fistulas are a long-term problem requiring medications, cleaning, and patience. It may take several months for your pet’s fistulas to resolve if they resolve at all. It is very important to give all medications prescribed by your veterinarian at regular intervals and to keep your pet’s anal region clean and dry.

After surgery your pet will have stitches that need to be removed two weeks post-op. It is important to prevent your pet from causing further irritation to the incision site by licking and scooting. Keeping the e-collar on will prevent licking from occurring. Hot compresses applied to the incision site multiple times in a day for several days after surgery will help to keep the anus clean. Any medication prescribed must be given as instructions indicate.