January Case of the Month: A Sight to Behold: Catching Cancer in Time

During a herd dispersal sale, one of our clients rescued a young paint horse that had one wall eye, non pigmented pink skin and white hairs around it. The gelding was under weight with a heavy parasite load. He also had irritated skin and eyes, as did most of the other horses rescued.  While trying to improve his overall health and condition, the owners noted his ongoing ocular discharge. After 6 months, the owners noted an irregular pink mass growing in the white part of the horse’s eyeball, the sclera.

The horse was referred to local veterinary ophthalmologist Dr. Burn, who was able to successfully remove the 4mm raised pink mass at the gelding’s home with just standing sedation. The mass was sent for histopathology and confirmed the suspicion of Squamous Cell Carcinoma (SCC).

Ocular SCCs are the most common tumour of the eye and can affect the eyelids, eyeball or conjunctiva. The tumours can grow rapidly invading deeper tissues and ultimately affecting the horse’s vision. Early detection, removal and subsequent management are imperative in having a successful outcome.

Researchers at UC Davis have found a variant in the gene responsible for repairing UV-damaged tissues. Those horses (and breeds) that carry this genetic variant are predisposed to developing ocular SCC although it does not explain the occurrence in all cases.Currently, the gelding’s eye appears normal and he’s being managed with sunscreen on nonpigmented skin and a UV protective fly mask. If he develops evidence of SCC regrowth, there is a topical chemotherapy available.