Successful medical treatment of an orbital osteoma in a dog.

A 6-year-old neutered male German Shepherd-mixed breed with a 2-month history of bilateral conjunctival hyperemia, epiphora, and a firm, slowly progressive swelling of the medial canthal region of the left eye (OS) was examined. Ophthalmic examination OS revealed a firm and smooth mass, extending from the medial canthus toward the medial orbital wall. Indirect ophthalmoscopy revealed indentation of the nasal part OS, which corresponded to the position of the orbital mass. Orbital neoplastic diseases were the main differential considerations. Computerized tomography revealed a bony smooth orbital mass without bone destructive features. Biopsy was performed, and histologic features were suggestive of osteoma. Systemic nonsteroidal anti-inflammatory (NSAID) drugs resulted in complete mass regression and absence of clinical signs for 5 years following initial diagnosis. This report describes the first case of canine orbital osteoma, which was responsive to NSAIDs.