Summer is not just the time for pinkeye , it’s also the time we see more cancer eye in cattle. These are fast-growing cancers of the eyeball or eyelids.
Early detection and treatment of eye cancers a) makes the treatment itself simpler, and b) minimises the risk of the cancer spreading (both locally around the eye and to bone and lymph nodes).
What are the risk factors for cancer eye?
There are two main risk factors. The first is lack of pigmentation – of the eyeball and upper, lower and/or third eyelids. Cows with white faces and pink third eyelids are more likely to be affected (for example we never see them in Jersey cows who have dark third eyelids).
The second risk factor is high levels of UV exposure. Just as the high UV levels in Australia predispose people to skin cancers, they also increase the risk in our pasture-based dairy cattle (speaking to North American vets, eye cancers are a rarity in their barn-raised cattle). Cattle with bulgy eyes (like Herefords) are more likely to have cancers on the eyeball itself as the exposure to UV is greater.
What do eye cancers look like?
Cancers of the third eyelid are the most common form of eye cancer. Third eyelid cancers vary from small, pink, wart-like lesions a few mm in diameter to larger, dark pink and sometimes ulcerated and infected lesions (see photos below).
Cancers on the eyeball are light pink plaques on the line where the dark and white parts of the eye meet and generally range from ½ to 1-cm diameter.
What is the best way to treat eye cancers?
Small third eyelid cancers are easily removed under local anaesthetic and, if caught early, have a low chance of recurring. In cases where the cancer has spread behind the eye, the whole eye will have to be removed. Sometimes these cancers recur. Cancers on the eyeball itself can sometimes be frozen off, but generally the whole eye needs to be removed.
Cows with small cancers (smaller than a 5c piece) are able to be sold through the yards however we recommend sending these cattle with small eye cancers direct to an abattoir. Affected cattle with any bleeding or discharge are not allowed to be sold.
Waiting a couple of weeks between detection of the cancer and having it treated can mean the difference between a simple third eyelid removal and taking out the entire eye, or even having to euthanase the cow: the best way to treat eye cancers is quickly!
Cancer eye tips
When silage season finishes for your farm, make a concerted effort to be on the look-out for eye cancers in your herd:
- Make sure there is a whiteboard or notebook handy to write down cow numbers while you’re milking and pay particular attention to the side of the cow that you don’t usually see (for example, in a rotary at cups on you might only see the left side of the cows).
- Ensure whoever is getting the cows to and from the dairy has something to record cows’ numbers such as a phone or notebook so they don’t get forgotten
- If someone is working with cattle, such as pregnancy testing or AI-ing, remind them to look out for eye cancer as sometimes, being higher, it makes it easier to spot them
The most important part in the treatment of eye cancers is to catch them early! If you spot one, CALL the vet that week!