Long-term prospective evaluation of topically applied 0.1% tacrolimus ointment for treatment of perianal sinuses in dogs.

Objective-To evaluate effectiveness of a combination of topically applied tacrolimus, orally administered prednisone, and a novel-protein diet for treatment of perianal sinuses in dogs and to monitor clinical progress and owner management of the condition for 2 years. Design-Noncontrolled clinical trial. Animals-19 dogs with perianal sinuses. Procedures-Perianal sinuses were diagnosed during physical examination, and dogs were placed on a 16-week treatment protocol consisting of topically applied 0.1% tacrolimus ointment, orally administered prednisone (tapering dose), and a novel-protein diet. Metronidazole was orally administered for the first 2 weeks. Anal sacculectonny was recommended whenever anal sacs were involved. Dogs were evaluated every month for the first 4 months and then every 6 to 12 weeks for 2 years. Results-Perianal sinuses resolved completely in 15 of 19 dogs during the 16 weeks. In the remaining 4 dogs, the lesions markedly improved but failed to completely resolve. Three of these had anal sac involvement, and the owner of 1 dog had complied poorly with treatment instructions. During the 2 years following treatment, all dogs were maintained on intermittently applied tacrolimus ointment, 4 dogs also received prednisone every other day, and 11 dogs remained on the novel-protein diet. At the conclusion of the study, 13 of the 15 dogs that survived to that point were free of perianal disease. Conclusions and Clinical Relevance-The described protocol was effective and economical for resolving perianal sinuses. Dogs maintained on intermittent medications were unlikely to redevelop lesions. When the anal sacs were involved, anal sacculectomy appeared to improve the outcome. (J Am Vet Med Assoc 2009;235:397-404)