Eye tumors in dogs aren’t something you hear about every day, but it’s important to recognize that they can happen. Primary intraocular tumors, which start inside the eye itself, are rare.
Spotting these tumors early and getting your dog to the vet quickly is key for successful treatment.
In this article, we’ll provide a complete breakdown of eye tumors in dogs, covering the different types, what might cause them, the signs to watch out for, how they’re diagnosed, treatment options, and what you can expect moving forward.
Types of Eye Tumors in Dogs
Eye tumors in dogs can be classified by where in the eye they originate.
Uveal Melanoma
Uveal melanoma is the most common type of primary intraocular (inside the eye) tumor in dogs. These tumors arise in the uveal tract, which is made up of the iris, ciliary body, and choroid of the eye. The good news is that over 80% of uveal melanomas are benign, meaning they aren’t cancerous. The other 20% are malignant, and while they don’t tend to spread to other parts of the body, they can be locally invasive.
Uveal melanomas tend to occur in dogs around the age of nine. Labrador Retrievers, Golden Retrievers, German Shepherds, Schnauzers, and Cocker Spaniels may be at higher risk for this type of tumor.
Limbal Melanoma (Epibulbar Melanoma)
Limbal melanomas originate at the limbus, which is the junction between the cornea and the sclera (the white part of the eye). These tumors are usually benign and easier to spot than those inside the eye.
These melanomas tend to grow very slowly and almost always turn out to be benign. They tend to appear on the side of the eye that’s furthest from the nose.
Other Intraocular Tumors
Other less common types of eye tumors that can occur inside a dog’s eye include ciliary body adenomas/adenocarcinomas and uveal schwannomas (which are rare and tend to occur mostly in blue-eyed dogs).
What causes eye tumors in dogs?
In most cases, the specific cause of eye tumors in dogs is unknown. Like many cancers, they seem to result from a complex combination of factors, including environmental influences and genetics.
Researchers suspect that genetics may play a role, as some breeds seem to be at higher risk than others. Labrador Retrievers, Golden Retrievers, German Shepherds, Schnauzers, and Cocker Spaniels may be more likely to develop eye tumors.
So far, the research hasn’t found any environmental factors that contribute to the development of ocular melanoma in dogs.
Symptoms of Eye Tumors in Dogs
The symptoms of an eye tumor can vary based on the type of tumor and where it’s located. Here are some of the signs you might see if your dog has an eye tumor.
General Symptoms
Here are some general symptoms associated with eye tumors in dogs:
- Redness
- Pain
- Vision impairment
- Glaucoma
- Corneal ulcers
- Uveitis
- Scleritis/Conjunctivitis
Uveal Melanoma Symptoms
These are some symptoms that are specific to uveal melanomas:
- Hyphema (blood in the anterior chamber of the eye)
- Dyscoria (abnormally shaped pupil)
- Secondary glaucoma
- Uveitis (inflammation of the uvea)
- Buphthalmos (enlargement of the eyeball)
- Lens subluxation (displacement of the lens)
- Retinal detachment
Limbal Melanoma Symptoms
If your dog has a limbal melanoma, you might see:
- A dark spot on the limbus (the border between the cornea and the sclera)
- A visible mass on the eye surface
Diagnosing eye tumors in dogs
If you notice a dark spot on your dog’s eye or if they’re showing other signs of eye problems, it’s important to get them checked out by a vet right away. A thorough veterinary exam is the first step.
To diagnose an eye tumor, your vet may use the following tools:
- Visual examination
- Ophthalmic exams to look at the structures of the eye
- Gonioscopy to check the eye’s drainage angle
- Ultrasound imaging
- MRI scans
- Fine-needle aspiration (FNA) to collect cells
- Biopsy to remove a tissue sample
- Histopathology (examining the tissue under a microscope, usually after the eye has been removed)
Your vet may also want to run X-rays or bloodwork to see if the tumor has spread to other parts of your dog’s body.
Treatment Options for Eye Tumors in Dogs
If your veterinarian suspects your dog has an eye tumor, it’s essential to discuss the various treatment options available. The best course of action depends on factors like the type, size, and location of the tumor, as well as your dog’s overall health.
Monitoring
In some cases, especially with small, benign-looking limbal melanomas, your vet might recommend a “wait and see” approach. This involves carefully monitoring the tumor for any signs of growth or change. Regular checkups and possibly photographs of the tumor can help track its progress.
Surgical Removal or Laser Therapy
For certain uveal melanomas, surgical removal of a portion of the iris (partial iridectomy) may be an option. Laser therapy can also be effective for some smaller tumors, aiming to destroy the tumor cells with concentrated light.
Enucleation (Eye Removal)
When tumors are large, painful, or suspected to be malignant, enucleation, or surgical removal of the entire eye, is often the recommended course of action. Enucleation allows for definitive diagnosis and treatment, ensuring the entire tumor is removed. It’s understandably a difficult decision for pet parents, but rest assured, dogs generally adapt very well to life with one eye.
Other Considerations
It’s worth noting that chemotherapy is generally not very effective for ocular melanoma in dogs. Therefore, treatment typically focuses on local control of the tumor through surgery or laser therapy.
What to expect
The outcome of an eye tumor diagnosis depends on the type of tumor your dog has and the treatments available to them. For instance, most ocular melanomas are benign, so the overall prognosis is good. For dogs with FPTOS, early removal of the eye is key.
The best thing you can do for your dog is to take them to the vet for regular checkups, including eye exams. When you pet your dog, get into the habit of looking at their cornea, sclera, iris, and other visible eye structures.
Follow your vet’s instructions, and don’t hesitate to seek a referral to a veterinary ophthalmologist if needed. Take things one step at a time.
In Conclusion
Eye tumors in dogs can be benign or cancerous, and they can appear on the eyelids, inside the eye, or in the tissues surrounding the eye. Early detection is key, so it’s important to regularly check your dog’s eyes and to see your veterinarian right away if you notice anything unusual. Treatment options vary depending on the type and location of the tumor.
As a responsible pet owner, one of the best things you can do for your dog is to make sure they receive regular veterinary care, including eye exams. Work closely with your vet to monitor your dog’s eye health and ensure the best possible outcome if an eye tumor is found.