If you've ever had an abscess, you know the pain of that pus-filled swelling. An anal fistula in a dog consists of an abscess in the perianal region, accompanied by fissures that repeatedly drain. A perianal fistula can be difficult to treat. In most cases, your vet will start with medical management and proceed to surgery if conservative treatment fails.
Also known as anal furunculosis, perianal fissure and anorectal abscess, a perianal fistula usually does not heal on its own. The anal lesion ulcerates, resulting in chronic infection. While any dog might develop a perianal fistula, the overwhelming majority of dogs with the issue are older German shepherds. That's possibly because of the low setting of the broad tail on this breed's body, which contributes to feces getting stuck in the perianal folds. German shepherds also have more of these glands in this area than other breeds, according to the American Kennel Club Canine Health Foundation.
Dogs suffering from perianal fistulas have difficulty pooping. They strain hard to eliminate. Blood likely appears in the stool. Your dog might constantly lick his rear end or scoot along the floor. He could lose his appetite and appear lethargic and depressed. You'll notice the swollen abscess or ulcerations, as well as smell them, when checking under the tail. More subtle signs include decreased tail wagging and reluctance to have the back end touched or to sit down.
Your vet will prescribe antibiotics to combat the abscess and infection. Cyclosporine, an immunoresponsive medication, is the drug of choice for treating perianal fistulas, along with oral antifungal tablets. Your vet might recommend dietary changes and stool softeners to make it easier for your dog to defecate. It could take months to tell whether medical management is sufficient. Your vet also might recommend amputating your dog's tail, along with removing his anal glands if the fistula affects them. Other surgical procedures include debridement, or removing unhealthy tissue from the ulcerated area, and using laser therapy on the fistula.
Prognosis and Care
Your dog will likely require treatment for the rest of his life. If he undergoes surgery, he might experience a prolonged period of fecal incontinence. Expect to clean your pet frequently. Your vet might recommend using baby powder on your dog's perianal region to help keep it dry. You might need to bring your dog to the vet for regular flushing of the fistula with disinfectants.