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If you’ve noticed a growth on your dog’s eye, it’s natural to immediately rush to the conclusion that your furry family member has cancer. Try to keep in mind that most dog eye tumors end up being benign (non-cancerous). But unfortunately, our canine counterparts can get eye cancer. We explore the various types of eye cancer in dogs and associated symptoms to help you understand what your pup may be experiencing. However, you should always contact your veterinarian about any eye changes you notice in your dog.
How Common Is Eye Cancer In Dogs?
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Dogs can develop a host of eye diseases and problems, but how prevalent is eye cancer in our furry friends? “Cancer inside the eye (intraocular cancer) in dogs is certainly not an everyday diagnosis, even though it is something we are always looking out for,” says Rebecca MacMillan, BVetMed, BSAVA, PGCertSAM, MRCVS, a companion animal veterinarian in Gloucester, United Kingdom.
“Instead, we see tumors on dogs’ eyelids and the soft tissue around the eye (extraocular cancer) much more frequently, and this type is more readily spotted by owners, too,” she explains. “Cancer tends to be found in our older canine patients, with melanoma and lymphosarcoma the most frequently diagnosed intraocular tumor types.”
Eye Cancer In Dogs Symptoms
Signs of benign and malignant eye tumors in dogs vary depending on the location and type of tumor. We’ll share more specific signs below for each type of eye cancer. But some common symptoms include:
- Excessive squinting or blinking
- Pawing at the eye or rubbing it on furniture
- Discharge or excessive tearing
- Cloudy or bloodshot eyes
- Discoloration of the iris or pupil
- A bulging or swelling of the eye
- Visible growth in dog’s eye
- Swelling around the eye
- Eyelid abnormalities
- Vision problems or loss of vision
- Difficulty seeing in low light
If you notice any of these symptoms, it’s important to take your pup to the veterinarian to get treatment as soon as possible. Early diagnosis and treatment can help minimize the chances of vision loss and other health problems.
Types & Locations Of Dog Eye Tumors
Just like humans, dogs’ eyes are complex structures, and there are many sites within the eye where benign and malignant tumors can form. Furthermore, the eyes and surrounding tissues contain many different types of cells, which produce varying types of tumors. Eye tissues and associated ocular structures can develop primary tumors or can be the site of spreading tumor cells from other parts of the body.
Dog Eye Melanoma
Melanoma can occur on any part of a dog’s eye, including the eyelids, the cornea, the iris, etc. One of the most common types of eye tumors in dogs, uveal melanoma, is usually benign. But about 20% of cases are malignant and require prompt treatment.
Early-stage dog eye uveal melanoma typically appears as a black spot on a dog’s eye iris or the tissue that surrounds the lens. Other signs and symptoms include persistent inflammation of the iris and surrounding tissue, blood vessel ruptures, glaucoma, vision loss, and pain. If caught early, iris melanoma can be treated with noninvasive laser surgery. But in later stages, enucleation (surgical removal of the eye) is often recommended.
Eyelid Tumors
Dog eyelid growths are fairly common, particularly in older dogs. But fortunately, most occurrences of eyelid neoplasia (another word for tumor) in dogs are benign. They typically appear as a slow-growing mass on the eyelid margin or inside of the eyelid and can range in color from pink to dark brown.
Types of malignant eyelid tumors include melanomas and squamous cell carcinomas, both skin-related cancers. Another type of cancer, called meibomian gland adenocarcinoma, can form in the meibomian glands, which are located on the edges of the eyelid and produce oils to lubricate the eye.
Because eyelid tumors tend to be irritating and disfiguring to our furry friends, veterinarians typically recommend surgical removal for both benign and malignant forms.
Conjunctival Tumors
The conjunctiva is a thin, clear membrane that covers the inside of the eyelid and the whites of dogs’ eyes. Lymphomas and mast cell tumors can develop in the conjunctiva. These require surgical removal. Conjunctival tumors typically grow faster than eyelid tumors and tend to destroy surrounding tissues and metastasize. These tumors can sometimes regrow, requiring regular checkups after surgery.
Orbital Neoplasia
These tumors form in the tissues of the cavity (orbit) that holds the eye. Because of the location in the back of the eye, orbital tumors cause swelling of the cornea, conjunctiva, and eyelid and the eyeball to bulge forward. They can also render the affected eye unable to move in conjunction with the other eye and a dilated pupil. However, they’re generally not painful.
Nearly 90% of orbital tumors are malignant, and the prognosis is often poor. Meningiomas are the most common type of orbital tumor. Surgical removal of the tumor is necessary (and even the eyeball in some cases). In addition to surgery, your vet may recommend radiation and/or chemotherapy to help prolong your dog’s life.
Corneal Neoplasia
Although far less common, tumors can occur in the cornea (the transparent tissue that covers the iris and pupil). Corneal tumors typically appear as a pink mass on the cornea’s surface. These types of tumors can be benign or malignant, with the most serious being squamous cell carcinoma. This eye cancer is aggressive and, left untreated, can lead to vision loss and blindness. Depending on the extent of the mass, treatment can include surgical removal of the mass and even the eyeball if the tumor has grown into the eyeball.
Diagnosis Of Dog Eye Tumors
To diagnose an eye tumor, veterinarians typically begin by evaluating your dog’s medical history and conducting a complete examination of the eye itself and surrounding structures. Your vet will use an ophthalmoscope to inspect the complex interior structures of your dog’s eyes and a tonometer to measure eye pressure.
Your vet may also perform additional diagnostic testing, including blood work, a biopsy of the affected tissue, and ultrasound, MRI, or X-ray imaging. These tests help determine the type and severity of the tumor as well as whether cancer is present in other parts of the body.
Treatment Of Eye Cancer In Dogs
If it turns out that your pup has eye cancer, treatment depends on the location, type, and extent of the cancer. Treatment may include any combination of surgery, noninvasive laser surgery, radiation, chemotherapy, cryotherapy (freezing the tumor to kill the cancerous cells), or removing the eyeball.
Dr. MacMillan says eye cancer can make changes to the pupil’s shape and size, as well as cause swelling and pain, especially if the tumor continues to grow. “Some of the cases I have been involved in have resulted in enucleation (surgical removal of the eye) as this immediately makes the dog more comfortable, allows for a definitive diagnosis, and helps to reduce the risk of cancer spread. Although it seems drastic, dogs can adapt remarkably well to having an enucleation, especially as their other senses are so keen (smell and touch).”
What To Expect With Eye Removal Surgery (Video)
If your vet has recommended enucleation for your pup’s eye cancer, be sure to check out the video below to put your mind at ease about the process.
How Can Pet Insurance Help With Vet Expenses?
If your pup has an eye tumor or, in the worse case, cancer, veterinary care can end up costing thousands of dollars that you likely haven’t planned for. But proactively covering your pup with a pet insurance policy before a big health diagnosis can protect your finances. However, it’s important to know that most pet insurance companies don’t cover pre-existing conditions. So it’s best to get your dog coverage as early in her life as possible.
Pet insurance covers a host of illnesses and accidents throughout your furry friend’s lifetime. A reasonable monthly premium can give you peace of mind, so you won’t have to worry about affording expensive treatment to save your dog’s vision or her life. Learn more to see if pet insurance is worth it for your family.
What Else Could Be Wrong With My Dog’s Eye?
Many of the symptoms we outlined above, including cloudy and bloodshot eyes, are also signs of more common eye diseases in dogs, like cataracts or glaucoma. Our furry friends are prone to a host of eye conditions, just like humans. See our guide on dog eye problems to learn more about other ocular disorders that could be affecting your pup’s eyes.