The study was performed to assess the safety, efficacy and economical benefits of combining oral cyclosporin and ketaconazole to treat perianal fistula (PF).

A prospective clinical study.

Nineteen dogs with PF were treated with a combination of ketaconazole (5.3-8.9mg/kg BID) and cyclosporin (2mg/kg, 1mg/kg, 0.75mg/kg or 0.5mg/kg BID). Dogs were assessed weekly for resolution of lesions and adverse effects. Serum trough levels of cyclosporin were measured weekly and routine haematology and biochemistry biweekly. The target range for cyclosporin was 400-600ng/ml.

Lesions resolved in 100% of dogs within 3-10 weeks. Vomiting, lethargy and hairloss were observed, none serious. The target range for cyclosporin was achieved in all but 2 dogs, by day 7. Even with serial decreases of cyclosporin the 2mg and 1mg groups measurements remained high. While the 0.5mg and 0.75mg groups achieved or exceeded the target range. Nine of the nineteen dogs (36.8%) experienced recurrence with 3 of these having multiple recurrences. All recurrences responded to repeat therapy. Cost was up to 80% less per day compared to cyclosporin (5mg/kg BID) alone and duration of treatment was also decreased.

The use of ketaconazole (7.5 mg/kg BID) and cyclosporin (0.5-0.75 mg/kg BID) is safe, effective and economical for treating PF.