MICROORGANISMS ISOLATED FROM THE CORNEAL SURFACE BEFORE AND DURING TOPICAL CYCLOSPORINE TREATMENT IN DOGS WITH KERATOCONJUNCTIVITIS SICCA

The effect that topical administration of cyclosporine would have on t he number and type of microorganisms isolated from the corneal surface of dogs with keratoconjunctivitis sicca was studied. Schirmer tear te sts were performed on and corneal swab specimens were collected from 6 1 eyes of 31 dogs with keratoconjunctivitis sicca prior to and after 3 , 6, and 12 months of treatment with cyclosporine. In eyes that respon ded to cyclosporine treatment (Schirmer tear test value increased by g reater than or equal to 5 mm/min, compared with pretreatment value), t he percentage of eyes from which bacteria were isolated after 3, 6, an d 12 months of treatment was significantly (P < 0.001) less than the p ercentage from which bacteria were isolated prior to treatment. Howeve r, among eyes that did not respond to treatment, we did not detect a s ignificant change over time in prevalence of bacteria or type of bacte ria isolated. The percentage of eyes from which fungi were isolated de creased during treatment; however, the small number of eyes in which f ungal culture results were initially positive precluded demonstration of a significant change. For all eyes, we did not detect any significa nt differences over time in the frequency with which specific bacteria l genera were isolated, with the exception of P hemolytic Streptococcu s spp. Opportunistic corneal infections were not detected even though none of the dogs received antibiotics. An increase in production of te ars, which contain anti-infection proteins, was believed to be the pri mary factor responsible for the decrease in the percentage of eyes fro m which microorganisms could be isolated.