Primary invasive ocular squamous cell carcinoma in a horse.

A 12-year-old Haflinger gelding was presented to the veterinary medical teaching hospital of the University of Zurich with a light-pink raised mass on the temporal limbus and conjunctiva of the left eye. Squamous cell carcinoma was confirmed histologically after keratectomy and cryotherapy. Seven months later, a smooth pink, progressively enlarging mass was observed within the cornea of the left eye. Ultrasonographically, the mass was not only infiltrating the corneal stroma but seemed to protrude into the anterior chamber. The globe was surgically removed and submitted for pathology. A histologic diagnosis of corneal ocular squamous cell carcinoma with deep stromal invasion, infiltration of the uveoscleral meshwork and iridocorneal angle and resulting intraocular extension was made. This is the first detailed description of a limbal squamous cell carcinoma with invasion into the cornea and uvea in the horse.