Peri-anal fistulas start as an inflammatory process of the sebaceous and sweat glands within and around the anal region. When secondary infection sets in, abscesses are formed which then open and drain their contents. The area around the anus and the tail, which is warm and moist, create a favorable environment for bacteria to grow and multiply and initiate infection in surrounding tissues.
Peri-anal fistulas have been observed to be more common in middle aged dogs, usually between 5-8 years old. However, it can also occur in very young dogs younger than a year and older than 15 years.
Among the different dog breeds, German shepherds account for more than 84% of diagnosed cases of peri-anal fistulas. Possible reasons for this common occurrence in German shepherds include the presence of more glands in the peri-anal area compared to other breeds of dogs and the way their tail is set and carried. Another possible reason is that German shepherds are more prone to immune-mediated conditions. Aside from German Shepherds, peri-anal fistulas have also been reported in Border Collies, Labrador Retrievers, Bulldogs, Irish setters, Spaniels, Old English Sheepdogs, and mixed breeds.
One of the most noticeable signs that a dog has a problem in his anal region is the constant chewing and licking of the peri-anal region and frequent dragging of his anal area across the ground or floor. The dog may suffer from diarrhea or constipation and may pass stools more frequently. The dog may also have difficulty and feel pain when passing stools. Straining may also be seen and its stool may contain blood.
Due to frequent licking, chewing, and/or scooting across the floor, ulcers and bleeding may occur around the anal region of the Labrador. There may also be a discharge which is foul-smelling. The sizes of the ulcers may vary from being very small to more than several inches in diameter. In generalized cases, the ulcers may extend up to the tail. Some dogs may experience poor appetites and start to lose some weight. The dog may not allow close examination of the area and even lifting the tail causes extreme pain. The anal area may also appear darker because of skin pigmentation as a result of its chronic state.
Treatment may involve both medical and surgical intervention. For mild cases, treatment may include clipping the hair in the affected area, cleansing with antiseptic, and hydrotherapy (flushing the area with generous amounts of water). For serious cases of peri-anal fistulas, an oral cyclosporine and ketoconazole combination have been shown to be effective.
Treatment usually lasts for 8-9 weeks depending on the dog’s response. Recurrence is often common after treatment has stopped. Surgery may be done but the complications after surgery, such as fecal incontinence and anal stenosis, make it as the solution of last resort.