Comparative clinical evaluation of tacrolimus and cyclosporine eye drops for the treatment of canine keratoconjunctivitis sicca.

The aim of this study was to evaluate the efficacy of tacrolimus eye drops in alleviating the clinical symptoms of canine keratoconjunctivitis sicca (KCS) and to compare this efficacy with that of cyclosporine. The clinical study was conducted on 40 dogs diagnosed with idiopathic KCS. The dogs were divided into two groups of 20 animals each. In Group I, 0.75% cyclosporine eye drops were administered three times a day, while in Group II 0.02% tacrolimus eye drops were given twice daily. In addition, each group was subdivided into three subgroups based on the results of Schirmer tear test I (STT I). Clinical and ophthalmologic examinations were performed prior to the treatment as well as after one and two months of therapy. The application of both tacrolimus and cyclosporine resulted in a significant reduction of neovascularisation after the first and second month of treatment (P < 0.05, P < 0.001); however, in moderate and advanced stages, the observed efficacy of tacrolimus was higher. Across all patients, a significant increase in STT I values was observed after both the first and second month of treatment with tacrolimus (P < 0.01), as well as after two months of treatment with cyclosporine (P < 0.05). In both groups, some patients were observed to exhibit inhibited development of pigmentation, but an analysis of particular clinical cases and statistical data revealed no statistically significant discrepancies in the course of the study. In cases of advanced canine KCS, the efficacy of tacrolimus may be higher than that of cyclosporine.