Use of an ophthalmic formulation of megestrol acetate for the treatment of eosinophilic keratitis in cats.

OBJECTIVE: To evaluate a compounded ophthalmic formulation of 0.5% megestrol acetate to treat eosinophilic keratitis in cats. STUDY DESIGN: Prospective study. ANIMALS STUDIED: Seventeen client owned cats with eosinophilic keratitis in one or both eyes. METHODS: Eosinophilic keratitis was confirmed by cytology. At each visit, fluorescein staining and photography were performed. Cats were initially treated q 8-12 h with 0.5% megestrol acetate in an aqueous base. Serum glucose was measured at the first or second reexamination. RESULTS: Fifteen of 17 (88%) cats had a positive response to treatment, with 6 of 17 (35%) having complete resolution at the first reexamination (2-4 weeks). Two of 17 (12%) cats did not respond to treatment. Most cats required a treatment frequency of once daily to once weekly to maintain remission of disease. No ocular irritation or systemic side effects were noted in any cat. CONCLUSIONS AND CLINICAL RELEVANCE: The use of an ophthalmic formulation of 0.5% megestrol acetate is a viable option for treating feline eosinophilic keratitis.