Eye Cancer Symptoms in Dogs

Updated April 17, 2017

Cancer in dogs, like humans, can develop directly in the eye itself or from a malignancy in another part of the body that spreads to the eye. Some cancers in a dog's eye appear as colour changes, while others develop as visible growths. Knowing how to spot canine uveal cancer symptoms so you can get them biopsied can help you save your dog's eyes and possibly even its life.

Colour Changes

Melanomas can show up in a dog's eye as dark brown spots that are either flush with the iris or appear as raised nodules.This usually happens in the iris, but it can sometimes appear as a dark discolouration on the white of the dog's eye. The white of the eye could also develop a bloodshot appearance or reddening of its edges; bloody areas (hyphema) could also appear in the anterior chamber of the eye. Additionally, the cornea may develop a slight milky-white cloudiness that differs from cataracts, which form in the eye's lens, not its cornea. Any of these colour changes should alert you to take your dog to the veterinarian for a check-up.


Cancerous growths or enlargements could appear in a dog's eye(s) as either a change in shape or size or as a visible growth attached to the eye itself. If the pupil of the dog's eye appears to be persistently dilated or the shape starts to change from its usual circle, it could be a sign of cancer. The vet should also check swelling that appears in any part of your dog's eye, especially if it appears to adversely affect vision. The growth of an actual node or mass on the eye definitely calls for a vet exam.


Pain is one of the tougher symptoms to recognise when a dog develops cancer in its eye. Since dogs can't vocalise what's causing them discomfort, you'll have to pay close attention to your dog's moods and actions. A dog scratching or rubbing the area around its eye--whether yelping or not, squinting when outside or in a bright room, or tearing up in one or both eyes could be symptoms of a malignant condition. They could also signal an infection, which still dictates a vet visit.

Other Symptoms of Illness

As with any illness, a marked change in behaviour is a good sign that something is wrong with your dog. Any of the above physical symptoms appearing in or on a dog's eye, together with a loss of appetite and weight, a decrease in playfulness and other regular activity, and an overall decrease in energy definitely warrant a visit to the vet for an exam, testing or both. If the tested eye tissue is indeed malignant, your vet will help you determine the course of treatment for the dog's eye cancer.

Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

Beth Shumate is a freelance writer and full-time tourism communications manager whose over 25 years of writing experience includes news reporter, magazine contributor and software documentation writer. She holds a Bachelor of Arts in journalism from Henderson State University in Arkansas, and proudly became a Texan in 1987.