Evaluation of compounded cidofovir, famciclovir, and ganciclovir for the treatment of feline herpesvirus ocular surface disease in shelter‐housed cats

Abstract Objective To assess the efficacy of compounded cidofovir, famciclovir, and ganciclovir for the treatment of feline herpesvirus type 1 (FHV‐1) ocular surface disease. Animals studied 132 shelter‐housed cats qPCR positive for FHV‐1. Procedures A masked placebo‐controlled study design was utilized. Animals were enrolled in one of four treatment groups: topical ocular placebo + oral placebo ( n = 32), compounded cidofovir 0.5% ophthalmic solution + oral placebo ( n = 32), compounded famciclovir oral solution (90 mg/kg) + topical ocular placebo ( n = 32), and compounded ganciclovir 0.15% ophthalmic solution + oral placebo ( n = 36). Cats were treated with each medication twice daily for 7 days and were evaluated on Day 1 and Day 8 using an ocular scoring system, body weight, and qPCR for FHV‐1 viral load. Results Cidofovir significantly decreased viral load from Day 1 to Day 8 compared with placebo ( p = .024). Neither famciclovir nor ganciclovir decreased viral load compared with placebo ( p = .14, p = .41). There was no significant improvement of ocular scores for any drug group compared with placebo ( p = .62). In all groups, 65%–75% of cats improved from Day 1 to Day 8. Juvenile cats had a significant increase in weight gain compared with placebo for cidofovir ( p = .025) and ganciclovir ( p = .023). All corneal ulcers in placebo animals failed to heal whereas 77% of ulcers in antiviral group animals healed. Conclusions Topical ophthalmic cidofovir significantly decreased ocular FHV‐1 viral shedding and increased weight gain in juvenile cats. Ganciclovir increased weight gain in juvenile cats. Compounded famciclovir demonstrated limited efficacy for the treatment of FHV‐1 ocular surface disease in shelter‐housed cats.