Eye Cancer in Dogs

Eye cancer in dogs may be either primary, meaning that it originates in the eye itself, or secondary, meaning that it spreads to the eye from another part of the body. Many eye tumors in dogs aren't cancerous, but it's important to have any tumors or growths checked by a vet, to make sure. Read on to learn more about the causes, symptoms and treatment of eye cancer in dogs.

Causes and Types of Canine Eye Cancer

Vets don't really know what causes primary eye cancer in dogs. Melanoma, or skin cancer, of the eyes often occurs in dogs with light eyes. Often, however, eye cancer seems to occur as a result of old age. 

Primary eye cancer in dogs is most often due to melanoma. When cancer spreads to the eye from another part of the body, it's usually a type of cancer known as lymphosarcoma, which spreads through the lymph glands.

Symptoms of Canine Eye Cancer

Dogs with eye tumors may experience inflammation and excess tear production. The eye may itch, causing your dog to scratch at it excessively. Your dog's eye color may change, or his eyes may become oversensitive to light. The shape of his pupil might change and you could notice bleeding in or from the eye; you may even be able to see a tumor or growth in or near the eye.

Eye cancer can affect your dog's whole body, causing symptoms that don't seem to have anything to do with the eyes. These can include:

  • Lowered appetite
  • Weight loss
  • Lethargy
  • Listlessness

When dogs suffer from eye tumors, whether cancerous or benign, they can experience glaucoma, or increased pressure inside the eye, and even vision loss.

Diagnosing and Treating Canine Eye Cancer

Your vet will need a complete medical history and thorough physical exam in order to diagnose canine eye cancer. Your vet will perform an eye exam and may need to take MRIs or ultrasounds of the eye. Blood work will be necessary, and your vet may take X-rays of the chest and abdomen to see if the cancer is present in other organs.

If your dog's eye cancer is primary and has not yet spread, your vet may be able to treat it by surgically removing the eye, or by removing the eye tumor with laser surgery. A biopsy of the cancerous tissue will be necessary for your vet to determine the best treatment, but chemotherapy or radiation therapy may be an option, especially if the eye cancer is secondary or has already spread.

Most eye irritations in dogs are not the result of eye cancer. Most canine eye symptoms are due to conjunctivitis, deformities of the eyelids, or injury to the eye. Even when tumors occur, they usually aren't cancerous. Any canine eye problem can, however, lead to vision loss, and you should see your vet right away if your dog develops any pain, inflammation, itching, unusual discharge or other eye symptoms.