Clinical and light microscopic studies of the conjunctival tissues of dogs with bilateral keratoconjunctivitis sicca before and after treatment with topical 2% cyclosporine

We determined the concentrations of goblet and immune cells in conjunctival imprints and tissues of canines with keratoconjunctivitis sicca (KCS) before and after cyclosporine A (CsA) treatment. Twelve dogs with bilateral KCS were assigned to three groups: untreated, treatment group 1, and treatment group 2. The treatment groups were treated topically with 2% ophthalmic CsA solution for 45 days; CsA treatment group 2 was followed for an additional 30 days after discontinuation of the drug. Schirmer tear test (STT) scores were recorded prior to CsA treatment and on alternate days throughout the experiment. CsA treatment improved the STT scores, restored conjunctival histology, increased goblet and epithelial cell numbers, and decreased numbers of inflammatory cells. Although the STT scores regressed slightly at day 30 after discontinuing the treatment, the scores were higher than the baseline values. Topical CsA treatment resolved clinical signs of KCS, improved STT scores and restored normal conjunctival histology.