Cancer eye is the most common tumor affecting cattle. The tumor may be found on the eye, the third eyelid, or on the upper and lower eyelids. The condition causes significant losses to cattle producers due to loss of production, treatment cost, early culling, and slaughter condemnation. Several treatment options are available, but the most important factor in treatment is early detection.
Although the cause is not completely understood, certain factors such as genetics, nutrition, ultraviolet light, lack of pigmentation around the eye, and viruses predispose cattle to developing cancer eye. All breeds of cattle may develop cancer eye but breeds that lack pigmentation around the eye are more susceptible than others. Herefords, Hereford crosses, and Holsteins tend to have more cases. Beside breeds of cattle, studies show that genetics plays a role in susceptibility. Cattle in the southwest with abundant sunlight tend to have more problems with the disease. For reasons that cannot be explained, cattle on high plains of nutrition are more likely to have tumors. Herpes virus and bovine papilloma virus may play a role in the disease. These viruses have been isolated from tumors. The role is not completely understood.
As mentioned earlier, tumors can be found in different sites on and around the eye. The tumor begins as a benign plaque. Plaques are small raised white areas on tissues. The plague will progress to a keratoma, papilla, and then cancer. Keratomas are skin growths. Papillomas are wart like growths. Carcinomas are pink in color and nodular in appearance. Plaques, keratomas, and papillomas are benign tumors that may or may not progress to a carcinoma. If cancer eye is left untreated, it can metastasize to regional lymph nodes.
Most cancer eyes are diagnosed by clinical signs. Using a microscope to aid in the diagnosis, veterinarians may do an impression smear to look for certain cells. To confirm a diagnosis, samples can be sent to an animal diagnostic lab where histology will be performed.
Many options are available to treat cancer eye. The key to success is to treat early before the tumor gets too large or metastasizes. Surgical excision of the tumor is the most common treatment and works well if the tumor is small. A good time to look for tumors is during pregnancy testing. Small plagues and papillomas can be scraped off the cornea or eyelids at this time before they become cancerous and large. If the eye tumor is large, the eye may need to be removed. Cryotherapy is a simple method to remove small tumors where tumors are destroyed from freezing the tissue. Hyperthermia uses heat to destroy cancer cells. This therapy is simple and works well. Radiation and chemotherapy have been used with success but are more expensive.
Preventing cancer eye begins with good husbandry. Cattle need to be observed frequently for any signs of tumors. The quicker tumors are dealt with the better chance of a positive outcome. Cattle producers should select for cattle with pigment around their eyes and never keep replacement cattle from bulls or cows that have cancer eye.
Cancer eye is the most common cancer in cattle. It is also one of the common causes of carcass condemnation and cost the cattle industry several million dollars a year. Cattle producers should be quick to treat when tumors are found. For more information about cancer eye, cattle producers should contact their local veterinarian or local Oklahoma State University County Extension Agriculture Educator.