Anal furunculosis, also known as perianal fistulas, is a chronic inflammatory disease of the perianal region (the area surronding the anus).

Your dog will have ulcerated wounds or lesions around the anal area that will not heal. The lesions will be deep and may be painful. Other common symptoms of anal furunculosis in your dog include straining when trying to defecate or difficulty defecating, licking or chewing around the anus, smelly discharge often with pus or mucus, low tail carriage, weight loss and lethargy. Despite these many potential symptoms, because the symptoms develop gradually they may go unnoticed. In addition, it is sometimes hard to see any lesions because they are often hidden under the hair surrounding the anal region.

Most dogs afflicted with anal furunculosis tend to be middle-aged and intact (not neutered) males. Among purebred dogs, German Shepherds are the breed most frequently afflicted with anal furunculosis. The second most common breed is the Irish Setter.