A 10-year-old buckskin paint gelding was presented to the Cornell University Hospital for Animal’s Ophthalmology Service on December 2nd, 2014 for evaluation of a mass on his left lower eyelid and chronic clear ocular discharge OS. The mass was first observed approximately one month prior and has increased in size. Upon presentation the gelding’s physical exam was unremarkable except for his left eye and eyelids. Present on the medial ventral eyelid, on an area of unpigmented epithelium, was a small (approximately 4mm x 4mm) firm pink raised mass with a cauliflower surface. In horses, masses associated with the lid margins, especially those on unpigmented epithelium, are overwhelmingly definitively diagnosed as squamous cell carcinoma. Under standing sedation and locoregional anesthesia, the mass was removed uneventfully. Surgical excision was followed by radiotherapy with Strontium-90.

This case report details the history of a horse with ocular squamous cell carcinoma, the diagnostics utilized for work-up of such a case, and the potential treatment options, including surgical excision and radiotherapy. This case report presents information on ocular squamous cell carcinoma and describes theorized risk factors associated with the development of this cancer.