Shadow, a 7-year-old neutered German shepherd dog, was presented with signs of tenesmus, dyschezia, licking of the anal area, and mucopurulent anal drainage with an odor.
History. These signs had been present for more than a year but had progressively worsened.
Physical Examination. Shadow was reluctant to have his tail lifted. Following sedation, a rectal examination revealed mild thickening (2 to 3 cm) inside the anus. There were multiple draining tracts within the entire circumference of the anus (Figure 1, above).
Ask yourself ...
For this advanced case of perianal fistula, what is the approach to management that is most appropriate and gives the best chance of a successful outcome?
A. Surgical management with a laser to ablate each fistula
B. Surgical management with deroofing of each fistula, followed by electrocoagulation or fulguration
C. Administration of prednisone and cephalexin for several weeks
D. Treatment with the immunosuppressive drug cyclosporine because perianal fistulas in German shepherd dogs are due to an immunologic defect that affects the colon as well as the perianal area
- Correct Answer: D -- Treatment with cyclosporine
The cause of perianal fistulas remains unclear. German shepherd dogs are the most common breed affected, but fistulas may be seen in other breeds, such as Irish setter dogs. Many of the breeds in which perianal fistulas occur have broad sloping tail heads, which may predispose them to fistulas. In addition, there is a reported link between colitis in the German shepherd dog and perianal fistulas.1