A perianal fistula is an abnormal erosion, canal, or tunnel in the delicate tissues around the anus. These fistulas or tracts generally lead to the rectum or an infected area (abscess), such as the anal sacs.
Although any breed is susceptible, perianal fistulas are most common in German Shepherds and Shepherd mixes, Irish Setters, Retrievers, Collies, and Spaniels.
The condition is very painful and causes constipation and/or painful elimination, bleeding, dragging the anus on the ground or floor, and a foul-smelling discharge. Treatment is either surgical or medical, depending on the severity of the condition.