Perianal fistulas are painful, chronic ulcerating tracts around the anus of dogs, most commonly affecting German Shepherds, with an immune-mediated cause requiring long-term management.
Perianal fistulas cause constant pain. The ulcerating tracts are chronically inflamed and highly sensitive — defecation causes searing pain that affected dogs dread, sometimes leading to constipation from avoidance. The persistent malodor and discharge causes significant hygiene problems. Dogs affected by severe perianal fistulas are in evident discomfort throughout their waking hours. Before the cyclosporine era, surgical management was the only option and carried high complication rates including fecal incontinence. The behavioral impact is significant: dogs that were previously friendly may become aggressive due to chronic pain. The dramatic improvement seen with cyclosporine treatment — rapid resolution of lesions and return to normal behavior — starkly illustrates the severity of suffering that preceded treatment.