Comparative Efficacy of Topical Ophthalmic Ganciclovir and Oral Famciclovir in Cats with Experimental Ocular Feline Herpesvirus-1 Epithelial Infection

Abstract

Purpose: To determine the comparative efficacy of ganciclovir ophthalmic gel and famciclovir oral tablets in cats with experimentally induced ocular feline herpesvirus-1 (FHV-1) epithelial infection. Methods: A randomized, placebo-controlled trial was performed using 16 nonvaccinated, specific pathogen-free cats with experimental FHV-1 infection induced by topical ocular inoculation. Cats received topical ganciclovir 0.15% ophthalmic gel (1 drop 3 times daily, n = 6 cats), oral famciclovir (90 mg/kg twice daily, n = 6), or topical artificial tear gel (1 drop 3 times daily, n = 4) for 14 days. Cats were monitored after inoculation for 30 days. Ophthalmic examinations were performed every 2 days and ocular disease scores calculated. In vivo confocal microscopy was performed, and corneal leukocyte infiltrates quantified. Ocular samples for FHV-1 quantitative polymerase chain reaction (qPCR) and virus isolation assays were collected every 3 days. Hemograms and serum biochemistry panels were performed at intervals. Results: Clinical ocular disease scores and corneal leukocyte infiltrates were significantly lower in the ganciclovir and famciclovir groups compared with placebo, but no significant differences were detected between the antiviral treatment groups. Ocular viral loads determined by qPCR were significantly lower in the ganciclovir group compared with the placebo group, but there were no significant differences between the other study groups. Hemograms and biochemistry panels were unremarkable. Conclusion: Topical application of ganciclovir gel 3 times daily was well-tolerated and displayed similar efficacy at reducing clinical ocular disease scores and corneal inflammation as twice daily oral famciclovir treatment in cats with experimental ocular FHV-1 infection.

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

“…As most previous studies of antiviral medications for the treatment of FHV-1 have been performed in experimental animals with acute infections, it is therefore unknown how effective these medications may be for chronic or latent disease presentations. 24,33,35 Furthermore, the majority of cats in the present study were co-infected with at least one other pathogen including FCV, Mycoplasma spp., Chlamydia spp., and Bordetella bronchiseptica. These pathogens may have contributed to the ocular clinical signs observed in individual cats, and this secondary aspect of their ocular disease would not be expected to improve with antiviral treatment.…”

“…31,34 A recent abstract on the use of 0.15% ganciclovir ointment in cats experimentally infected with FHV-1 reported a significant improvement in ocular clinical signs for cats treated with ganciclovir compared with placebo treatment, and no significant difference in viral shedding compared with placebo treatment. 35 For this study, cats received topical ophthalmic 0.15% ganciclovir ointment three times daily for 14 days and were monitored for a total of 30 days following viral challenge. In humans with ocular HSV infection, 0.15% ganciclovir gel is initially used at a frequency of 5 times daily when HSV induced corneal ulcerations are present, followed by continued therapy for one additional week at 3 times daily once the corneal ulceration has resolved.…”

“…31,34 Ganciclovir (administered every 8 h) has preliminarily been evaluated in experimentally FHV-1 infected cats for the treatment of ocular disease and led to a significant improvement in clinical signs. 35 The objective of this masked placebo-controlled study was to simultaneously evaluate efficacy of three commonly utilized compounded antiviral drugs for the treatment of FHV-1 ocular disease in naturally-infected shelter-housed cats. Efficacy was determined by evaluating ocular clinical signs, quantifying viral shedding, and recording body weight before and after 7 days of treatment.…”

“…Based on previous research, we hypothesized that famciclovir would be the most effective antiviral medication by leading to improved ocular clinical signs, decreased ocular viral shedding, and increased weight gain in shelter-housed cats with FHV-1 ocular disease. 24,25,28,29,35…”

“…Ganciclovir, another antiviral medication applied topically to the eye, was shown to have high efficacy against FHV‐1 in vitro, and has been evaluated for ocular tolerance and side effects in cats, with no significant side effects noted following administration every 8 h over 7 days 31,34 . Ganciclovir (administered every 8 h) has preliminarily been evaluated in experimentally FHV‐1 infected cats for the treatment of ocular disease and led to a significant improvement in clinical signs 35 …”