Effects of feline herpesvirus type 1 on tear film break-up time, Schirmer tear test results, and conjuctival goblet cell density in experimentally infected cats

Objective - To determine the effect of feline herpesvirus type 1 (FHV-1) on tear film break-up time (TFBUT) and Schirmer tear test (STT) values in cats with primary experimental infection and to determine the relationship between TFBUT and STT values and conjunctival goblet cell density (GCD). Sample Population - 9 specific-pathogen-free cats of approximately 6 months of age. Procedures - 6 cats were inoculated with FHV-1; 3 control cats were sham inoculated. Clinical and histologic evidence of conjunctivitis and TFBUT GCD, and STT values were assessed at multiple times until postinoculation day (PID) 29. Results - In infected cats, mean clinical and histologic conjunctivitis scores peaked at PID 7 and remained above baseline at PID 29. In control cats, these 2 variables did not change from baseline throughout the study. Mean TFBUT declined rapidly in infected cats up to PID 15 and at PID 29 remained less than baseline, less than for control cats, and below reference range values. Mean STT value for infected cats at PID 29 was increased from baseline but was within the reference range and not different from the value for control cats. Mean GCD in infected cats declined precipitously by PID 7 and remained below reference range values at PID 29. Mean GCD in control cats remained unchanged for the duration of the study period. Conclusions and Clinical Relevance - FHV-1 induced qualitative tear film abnormalities in experimentally infected cats, as measured by TFBUT and GCD. Assessment of TFBUT provided a reasonable clinical estimate of GCD.