Evaluation of topical ophthalmic application of penciclovir cream in cats with experimental ocular feline herpesvirus-1 infection.

Abstract

OBJECTIVE: To determine the efficacy of topical penciclovir 1% cream for the treatment of cats with experimentally induced ocular feline herpesvirus-1 (FHV-1) infection. METHODS: A randomized, placebo-controlled trial was performed using 10 unvaccinated specific-pathogen-free cats with experimental FHV-1 infection induced by topical ocular inoculation. Cats received topical penciclovir 1% cream (n = 6 cats) or a placebo artificial tear gel (4) 3 times daily for 14 days. Cats were monitored after inoculation for 30 days. Ophthalmic examinations were performed every 2 days, and ocular disease scores were calculated. In vivo confocal microscopic ocular examinations were performed to quantify corneal leukocytes. Feline herpesvirus-1 quantitative PCR, viral titers, hemograms, and serum biochemistry panels were performed throughout the study. RESULTS: No significant differences in clinical ocular disease scores were observed between the penciclovir and placebo groups during the majority of the study period; however, penciclovir-treated cat scores declined more rapidly after study day 14. No significant differences were detected in corneal leukocyte infiltrates between study groups. Ocular viral loads determined by PCR were significantly lower in the penciclovir group on day 3 but were similar on all other sampling days. Hemogram and serum biochemistry values were unremarkable in all cats. CONCLUSIONS: Topical penciclovir 1% cream administered 3 times daily was well tolerated and modestly reduced ocular viral shedding but had minimal effects on clinical ocular disease in cats with experimental ocular FHV-1 infection. CLINICAL RELEVANCE: Refinements in the topical penciclovir treatment strategies and optimization of penciclovir formulations are recommended before clinical applications in cats.