Cancer eye is easily confused with other eye conditions such as trauma (due to injury or grass seeds) and pink-eye. Therefore, it is recommended to have any cow with a "sore eye" examined by a veterinarian.
The typical cancer eye of cattle is a squamous cell carcinoma, which often is highly malignant, ie it readily spreads to or invades surrounding tissues. Cattle with unpigmented eyelids appear to be more susceptible.
In case of cancer, surgery is not recommended if there is any evidence of spread. Slaughter is not an option either, as these animals invariably are condemned. Cancer eye cattle will be condemned when:
- There is evidence of spread from the eye to any lymph node or other structure
- The condition has involved the bony structures of the head, together with inflammation, a pussy discharge or necrosis
- The carcass condition is poor or there is evidence of toxic absorption, regardless of the size of the eye lesion
Writing out a "Works Certificate" does not guarantee that the carcass will pass meat inspection.
Regular inspection of all cows and culling of early cases is the best approach to dealing with cancer eye. Affected cattle require prompt veterinary attention, and should not be kept in the herd to finish their lactation. If surgery is deemed appropriate, then records must be kept and the animal checked on a regular basis.
Removal of the third eyelid (most commonly affected in Friesian cows in New Zealand) or the entire eye is no guarantee that all the cancer tissue/cells are being eliminated. Often the cancer recurs and may be of a more aggressive nature. Cancer eye also has a reasonably high heritability and any treatment or surgery should therefore be approached with caution.
As we approach that time of the season when you will not be looking at the cows every day, it may pay to cast your eyes over their eyes, and call Totally Vets so we can get onto any suspect cases before it is too late.
