In horses, tumors of the eye, skin and genital system are most common types of cancer seen. Cancer Eye is the common phrase used when a horse has a tumor or cancer in the eye, eyelid or conjunctiva. Unfortunately, these types of cancer are usually squamous cell carcinomas (SCC) which are malignant. Occasionally, this type of cancer can be a sarcoid which is not malignant.
Squamous cell carcinoma tends to occur in older horses with lightly or non-pigmented eyelids. Appaloosas and draft breeds tend to be most commonly affected with SCC. The eyelids, conjunctiva, third eyelid (nictitating membrane) and corner of the eye are the common areas. Usually, the horse develops a clear to cloudy discharge from the eye. The tumor is usually pink and fleshy in color and can be seen protruding from the eyelid or conjunctiva.
Treatment should involve surgically removing the tumor is possible. Follow up treatment includes "freezing" the tumor site or applying liquid nitrogen to the area to kill any remaining tumor cells. If the cancer cannot be excised, prescription ointments to kill the tumor can be used.
Unfortunately, SCC is malignant and can invade the tissue and bone surrounding the eye. Many times, the cancer will recur even after excision. Enucleation or removal of the entire eye is necessary in advanced cases. If you see an abnormal discharge or pink like growth from your horse's eye, you should call your veterinarian for an examination.
Below are pictures of a Belgian stallion with squamous cell carcinoma of this third eyelid. The third eyelid is an eyelid which is located in the middle corner of the eye and covers the entire eye when needed. It is used to protect the eye. The tumor is visible as the pink, raised mass in the middle corner of his eye. I excised this tumor and used cryosurgery after the excision to kill any remaining tumor cells.
