Ocular squamous cell carcinoma (SCC or cancer eye) is the most common tumor in cattle. Early eye lesions can be benign, while more advanced lesions tend to be malignant and metastasize (spread) to other organs. The cause of cancer eye is not positively known. It is associated with a lack of pigmentation around the eye and chronic irritation, often coming from solar radiation (sunlight) or other eye conditions such as pinkeye. Genetics and maintaining a high plane of nutrition are also associated with the development of SCC. It is most commonly seen in Hereford cattle, and some Simmental and Holsteins where non-pigmented eyelids are present.
Similar to pinkeye, animals affected with cancer eye are painful and may be observed squinting and have a partially closed eye with excess tearing. It’s important to check the cow more closely if you observe any of these signs to differentiate pinkeye from cancer eye. Any wart-like growth, erosion, or scab on the eyelid or on or around the eye should be examined more closely or recorded so that you can recheck it later.
Lesions usually begin as small plaques or growths on the edge of the colored part of the eye. These can be easily treated if detected early. Older lesions may appear like a wart or papilloma, usually rising from the third eyelid on the medial or inner edge of the eye. Cancerous lesions that have damaged the eye beyond repair but have not yet displayed signs of metastasis or movement to adjacent lymph nodes can be surgically removed by enucleation or removal of the eye. Once the cancer has spread to other organs and lymph nodes, the animal needs to be culled as soon as possible or when her calf is weaned; the carcass from that animal will likely be condemned.
Cancer eye results in significant economic loss due to condemnation at slaughter and a shortened productive life. Losses can be minimized if producers follow some specific management criteria. Examine the eyes of your cattle at least on a yearly basis and have your veterinarian examine any suspicious lesions that you detect. Select breeding stock with pigmentation around their eyes. The cancer is considered to be heritable, so do not retain offspring from affected cattle as replacements. Early treatment of ocular problems in cattle can mean the difference between a healed versus a salvaged animal. Remember the key to successful treatment is early detection, so consult your veterinarian whenever you notice a suspicious lesion or swelling on or around the eye.