Calcification and osseous metaplasia of the meibomian glands of a horse.

OBJECTIVE: To report the clinical history, surgical management, and histologic findings of meibomian gland calcification and osseous metaplasia in a horse. ANIMAL STUDIED: A 21-year-old Selle Français gelding presented with a 9 months history of blepharitis, blepharospasm, and epiphora affecting the right eye. The horse was diagnosed with meibomianitis and impaction with associated granulomas, but not treated surgically for 6 years. PROCEDURES: Physical and ophthalmic examinations, and systemic bloodwork were performed. A diamond burr debridement was performed on a corneal ulceration, and meibomian gland nodules were excised and examined histologically. RESULTS: Multiple firm concretions were associated with the palpebral conjunctiva of each eyelid. The largest nodule (5 × 4 × 10 mm) was excised from the lower right eyelid. Histology revealed dilated meibomian ducts with mineralized inspissated secretions surrounded by fibrosis and osseous metaplasia. Following nodule excision and corneal ulcer resolution, no blepharospasm or epiphora recurred for a follow-up period of 15 months. CONCLUSION: Calcification and osseous metaplasia of the meibomian glands was identified in a Selle Français gelding. It is suspected that inspissated meibomian secretions led to a local granulomatous reaction with secondary dystrophic calcification and osseous metaplasia.