A retrobulbar dermoid cyst with involvement of the sinus in an 18-year old pony.

This case report describes a retrobulbar dermoid cyst in an 18-year-old pony with an invasive character into the frontal sinus. CT imaging was important for the appropriate management of this case and the definitive diagnosis was obtained from histopathology. Surgical excision was performed successfully without recurrence 1-year post-operatively. The pony returned to its intended use and previous performance level, although complaints of mild symptoms of headshaking were noted in bright light only.