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Catching eye cancer in cows early

Catching eye cancer in cows early
The early stages of eye cancer. Photo Supplied.

When you’re working at the back-end of a dairy cow every day, it’s easy to miss what’s going on at the front-end, which means cases of cancer eye can go unnoticed until they are at a more advanced stage.

Senior large animal vet at VetSouth, Sunita McGrath, is keen for farmers to look out for this disease, officially known as squamous cell carcinoma, to improve treatment options and recovery.

“Cancer eye is as awful as it sounds and, like most types of cancer, early detection leads to better outcomes, so it’s good practice to check for it periodically,” she explains.

Eye cancer in its late stages. Photo supplied

“If you see a tumour in your herd, get it checked! Even if you can just send your vet a photo, they can usually give an indication as to whether it needs to be examined more closely, or removed straight away, leading to a much better result for you and the cow.”

Cancer eye is, as the name suggests, a cancer of the eye, which can affect the eyelids, eyeball or 'third eyelid' (the eyelid that slides across the eye).

These tumours are said to develop in cows due to a mixture of reasons; environmental, viral and genetic factors can all play a role. It is most commonly seen in unpigmented tissue, such as animals with white faces, but it is not just localised to these. It’s also related to ultraviolet radiation – not too dissimilar to skin cancer in humans.

According to Sunita, the initial stages of cancer eye are usually slow. It may just present as a tiny, knobbly growth on the third eyelid, which can be hard for farmers to detect during normal day-to-day routines. Cows may also have a slight discharge from the eye, due to irritation.

Over time, the tumour will (usually) continue to grow in size, eventually becoming a large mass that becomes necrotic and foul smelling.  At this stage it is far more obvious that something is wrong. If the tumour spreads, it can also cause the lymph nodes around the cow's head to swell up.

“Quite often, farmers may initially confuse cancer eye with pink eye and treat it themselves with a tube of eye ointment, which will offer no improvement. A vet visit is highly recommended to get onto the appropriate treatment early,” says Sunita.

“Early surgical removal of the lesion provides the best outcome and the prognosis is a lot better when the tumour is small in size, as the vet will be able to get good margins. Just a single cell left behind is enough to seed another tumour!”

Sometimes, the third eyelid may need to be removed, while other times, the whole eye might need to come out. If the tumour has invaded local lymph nodes, or has migrated into tissues around the eye, then removal is not an option. In cases like these, nothing can be done and culling the cow for pet food is the only option left.

Transportation to the works is not permitted for bad cases. Only a very small cancer eye is allowed, if certified by a vet. If the cancer eye has reached a late stage and is obviously very painful for the cow, a vet will not be able to write a works certificate, with the issue being compromised animal welfare.

Sunni’s main advice is: “If in doubt, get it checked out!”

By Georgia Evans

VetSouth