Cancerous eyes are a regular occurrence in most western Canadian beef herds and must be dealt with in the appropriate manner. Early detection and treatment alleviate the pain and suffering which occurs in advanced cases. Producers will also receive much greater financial benefits with early intervention.
Just as with pinkeye, cattle with white pigment around the eyes are more susceptible to cancer eye. Ultraviolet light, flies and other irritants such as dust may accelerate the development of lesions. It is thought there may be a genetic susceptibility to the disease, but this is not proven. Most producers should try and select cattle for dark pigment around both eyes. Herefords cattle are even being developed with this pigment.
Cancer eye (squamous cell carcinoma) usually starts as a plaque, which can progress to a papilloma (wart-like growth) and eventually progress to an invasive tissue-destroying mass. The goal is to recognize these early while surgery can be successful.
In cattle, approximately half of the precancerous plaques regress spontaneously. If you observe these on a cow, simply note her number and keep an eye on her for progression. These plaques may even remain for several years before advancing. About 80 per cent of entire carcass condemnations are the result of cancer eyes. In the United States an estimated one to 1.6 per cent of cattle will develop cancerous eyes in their lifetime. This is definitely an economic disease. If left until the orbit is eaten away, infection sets in and tremendous pain is the result. The SPCA can be called in, in these situations and charges can be laid.
The disease can metastasis, or spread to the local lymph nodes in approximately 10 per cent of cases. With stringent regulations in packing plants today, if some of the boney orbit is eaten out, or infection is present condemnation of the carcass usually results. The way to avoid this is early intervention and treatment of the disease by your veterinarian.
Several procedures can be done, depending on severity of the disease and the veterinarian’s expertise. A high percentage of cancers start on the third eyelid (nictitating membrane). This can be frozen and surgically removed without loosing the eye.
When pregnancy checking in the fall, I see this as an ideal opportunity to closely watch for eye problems as they walk through your system. If problems are noted they may even be dealt with immediately. Other tumours, if on the eyelids and not too advanced, can be treated, by your veterinarian, with cryosurgery (freezing with liquid nitrogen), heat therapy or an advanced surgery called a tarsoraphy. These procedures have a higher chance of reoccurrence, but again the eye is saved. When performing these procedures always have your veterinarian check the other eye closely as precursors to cancer are sometimes picked up.
In more advanced cases, especially if the cancer is on the eyeball itself, surgical removal of the eye and lids is the only option. Your veterinarian will usually need to consider several points in each case. At our clinic in late pregnancy (seven plus months bred) we generally will wait until just after parturition. Likewise in very early pregnancy we may wait as well, especially if the client wishes to keep the cow longterm. You must always consider the economic viability of the fetus when making decisions with regards to surgery.
Generally the veterinarian has a very good idea on the prognosis for reoccurrence. If the prognosis is very good, the cow can be kept for several more years. If guarded, she can be kept until weaning. Some cancer eyes, especially in large bulls or cows, are removed to ensure they pass slaughter. Each case has its own specifics, which must be addressed.
I always suggest quiet cows will remain quiet, even with one eye, whereas wild cows just get worse and should be culled. From a safety aspect, cows are always a danger working on the blind side. Bulls should have binocular vision to identify cows in heat so should be culled once the eye is removed and healed. We generally make sure fly control is adequate especially in the summer months. A fly tag or pour-on fly control product is a wise idea until the surgery heals.
Early recognition of cancer eye is the key. We have become more successful at treatment, as producers bring cases in early, before a lot of spread has occurred. Often a few weeks can make a huge difference in the success rate. Be careful not to confuse the early stages of cancer eye with pinkeye. Small tumours can cause irritation to the eye, which greatly mimics pinkeye. Check closely. In the early stages cancer eye is not painful and no eye spasms occur. There is a Cattle Facs sheet available at most auction markets or veterinary clinics, which have pictorial representations on what has been described
The cost of cancer eye treatments vary considerably, but are always substantially less than the value of the cow or bull. In order to avoid slaughter condemnations, or extend the life of a productive cow have affected eyes attended to. If in doubt have it checked, bad eyes are something all veterinarians can help you with.
RoyLewisisapracticinglargeanimal veterinarianattheWestlockVeterinaryCenter, northofEdmonton,AB.Hismaininterestsare bovinereproductionandherdhealth.