A 13-year-old Haflinger mare was admitted to the Cornell University’s Equine and Farm Animal Hospital for evaluation of a draining tract and firm swelling at the base of the right ear that was unresponsive to systemic antibiotic therapy and surgical debridement. Analysis of skull radiographs and CT scans revealed a dentigerous cyst as the underlying cause of the swelling and draining tract. Dentigerous cysts are congenital defects in the closing of the first branchial cleft. They are characterized by a dental element surrounded by a cystic lining which continually produces a mucoid secretion. Prognosis is good-to-excellent as these are benign. Surgical removal is warranted in cases of functional interference or for cosmetic reasons. For the patient in this report, surgical removal was successful.