Efficacy of topical aciclovir for the treatment of feline herpetic keratitis: results of a prospective clinical trial and data from in vitro investigations.
This study aimed to evaluate the efficacy of topical ophthalmic aciclovir applied five times daily as a treatment for feline herpesvirus type 1 (FHV-1) keratitis in a group of cats in a first-opinion practice setting. Cats with ocular signs indicative of FHV-1 or Chlamydophila species infection, predominantly conjunctivitis and keratitis, were tested for FHV-1 antigen using an immunofluorescent technique on air-dried conjunctival swabs. They were first treated with topical chlortetracycline with efficacy against Chlamydophila species and then, in cases positive for FHV-1, with topical aciclovir. The time to recovery was determined and illustrated using a Kaplan-Meier plot. Three cats were infected with Chlamydophila species and showed a median time to recovery of 14 days (95 per cent confidence interval [CI] 10 to 18 days), while 30 cats infected with FHV-1 showed a median time to recovery of 12 days (95 per cent CI 10 to 14 days). The drug dose at which 50 per cent plaque reduction (ED50) occurred in a standard plaque reduction assay was determined in an in vitro study. This showed a mean (SD) ED50 of aciclovir of 25 (3.5) mg/ml compared with 0.4 (0.05) mg/ml for trifluorothymidine, a drug known to be efficacious against FHV-1. The study shows that even though aciclovir is generally considered to lack efficacy against ocular FHV-1 infection, when used frequently it can have a beneficial effect in FHV-1 conjunctivitis and keratitis.
Williams
D L
DL
Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES.
Robinson
J C
JC
Lay
E
E
Field
H
H
D000212:Acyclovir / Q000008:administration & dosage / Q000627:therapeutic use*; D000287:Administration, Topical; D000818:Animals; D000998:Antiviral Agents / Q000627:therapeutic use*; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D005260:Female; D016849:Keratitis, Herpetic / Q000188:drug therapy / Q000662:veterinary*; D008297:Male; D016896:Treatment Outcome
D000998:Antiviral Agents; D000212:Acyclovir