Cat Eye Tumors: Types and How To Help Your Cat

A cat eye tumor is an abnormal growth in or around the eye that may appear as a color change, freckle, or visible bump. While some eye tumors are benign and slow-growing, others can be malignant (cancerous) and require prompt veterinary evaluation. 

If you notice changes in your cat’s eye, it’s important to schedule a veterinary exam. 

Early detection helps determine whether the growth is harmless or something more serious that needs treatment. 

What Is a Cat Eye Tumor?

An eye tumor is an irregular growth of cells either inside or around the eye. Sometimes this can look like a color change; other times it’s an actual bump on the surface of or around the structures surrounding the eye. 

A tumor is basically unchecked cell growth, meaning that the cells keep dividing and growing even when they’re supposed to stop. 

Eye tumors are not considered a medical emergency. 

If you note any changes in your cat’s eyes, make an appointment with your regular veterinarian to have their eyes checked out. They may refer you to a veterinary ophthalmologist if they see anything concerning. 

While eye tumors are not medical emergencies, there are other conditions, like lens luxation, which can be mistaken for a tumor in the eye. 

A luxation of the lens in the back of the eye is considered a medical emergency and is very painful. If your cat’s eye changes happen along with squinting, stumbling, or signs of sudden blindness, then get them to an emergency clinic right away. 

Types of Cat Eye Tumors 

Tumors of cat eyes can be put into two categories: benign and malignant (cancerous). 

The following are the most common benign, non-cancerous eye tumors in cats: 

• Iris melanosis: This looks like a small patch of pigment, like a freckle, on the colored part of the eye. While iris melanosis is benign and not something that is by itself dangerous, it can turn into a cancer called melanoma. 

• Limbal melanoma: A limbal melanoma is a rare benign tumor that grows on the limbus, the area where the sclera (white of the eye) meets the cornea. This can look like a dark-colored bump. 

• Hidrocystoma: These are benign, cyst-like growths that arise on the eyelids surrounding the eye. They usually have a dark color and are more common in Persians and Himalayan breeds. 

These are the most common malignant, cancerous eye tumors in cats: 

• Uveal melanoma: This is the most common type of ocular cancer in cats. This eye tumor develops on the iris (the colored part of the cat’s eye). It can start like a small brown freckle on the colored part of the eye and will grow and darken over time. 

• Feline post-traumatic ocular sarcoma (FPTOS): This type of cancer develops after an injury to the eye. If your cat has an injury to their eyeball, the vet may recommend removal of the eye (enucleation). Cats will often get tumors following traumatic injury to their eye, so removal of the eye is often recommended to minimize this risk. 

• Lymphoma: Ocular lymphoma usually happens in cats who have systemic lymphoma, meaning they have cancer throughout their body. It most often looks like their eye is changing colors, or the colored part of the eye develops a bumpy, thickened look. 

Symptoms of Cat Eye Tumors

The most common symptoms of cat eye tumors include: 

• Color change in the eye 

• Freckles or patches on or in the eye 

• Bumps on or around the eye 

• Cloudiness in the eye 

• Drainage from the eye 

Causes of Cat Eye Tumors

Cat eye tumors are caused by unchecked cellular division, meaning that the cells in or around the eye continue to divide even when they’re not supposed to. 

While it’s not completely understood why this happens in some cats and not in others, we know that both genetics and the environment can play a role. 

The most common type of eye tumor in cats is the uveal melanoma. Let’s explore how this cancer can develop through genetics or the environment. 

A cat may be genetically prone to getting benign iris melanosis freckles, where they have too much melanin pigment in their eye. Over time, this can change into a cancerous process. 

Additionally, a cat could get infected with a virus (like the feline leukemia virus or feline sarcoma virus), or have uveitis and the chronic inflammation (swelling) can also lead to cancer in the eye later on. 

Certain breeds of cat may have higher risk of developing specific ocular cancers than others. Himalayans and Persians get hidrocystomas more often than other breeds. 

Domestic Shorthair, Maine Coon, and Persian breeds have an increased risk of ocular lymphoma. 

One particularly dangerous type of eye tumor, the post-trauma sarcoma, occurs in cats who have had an eye injury. If your cat has trauma to their eye, they are at a significantly increased risk of getting feline post-traumatic ocular sarcoma (FPTOS). 

Long-term cigarette exposure can also increase a cat’s risk of developing ocular cancer. 

How Veterinarians Diagnose Cat Eye Tumors

To diagnose cat eye tumors, a vet will start with a complete ocular exam. They will use a tool called an ophthalmoscope to look inside your cat’s eye. 

They may do a full ophthalmic exam where they test various reflexes of the eye, measure your cat’s tear production, and test the pressure inside their eye. 

You may be referred to a veterinary ophthalmologist if more testing is recommended. 

Because the eye is very delicate, it’s tricky to collect cells to screen for cancer without removing the eye. If your vet is worried about cancer, they may recommend removing the affected eye. 

Treatment of Cat Eye Tumors

While some benign eye tumors don’t need any treatment at all, other cancerous eye tumors are often treated surgically. 

Cats diagnosed with iris melanosis, limbal melanoma, and hidrocystomas are often simply watched over time. Pet parents may be told to watch for any change in color, size, or texture of the mass(es) and keep a close eye out for any wincing or ocular drainage. 

If your vet is suspicious of a uveal melanoma or post-traumatic sarcoma, they will likely recommend an enucleation. Enucleation is the name of the surgery when the eyeball and all the surrounding associated tissues are removed. 

Sometimes eye medications are prescribed, like prednisolone or antibiotic ophthalmic drops (like ofloxacin), to keep your cat comfortable before surgery. 

If your cat is in pain, they may be prescribed pain medications for long-term use, like gabapentin, or short-term use, like Onsior. 

Ocular lymphoma is usually treated with systemic chemotherapy. This is done under the guidance of a veterinary oncologist. 

Recovery and Management of Cat Eye Tumors

Benign eye tumors will likely not go away, but frequent checking is recommended. 

If your cat needs surgery to treat their eye tumor, you can expect 10 to 14 days of recovery time. 

During this time frame, it’s very important that you prevent your cat from pawing at their eye and doing any face rubbing. 

A recovery cone (such as the Supet Adjustable Cone) is recommended to protect the incision while it’s healing. 

If your cat has any side effects from treatment, especially if they are being treated with chemotherapy, then they may benefit from Cerenia, a medication used for nausea. 

Probiotics, like FortiFlora, can also be helpful for cats struggling with GI upset following cancer treatment. 

Prevention of Cat Eye Tumors

Seeking to prevent cat eye tumors is difficult since there are many factors involved. But here are a few things you can do: 

• Avoid breeding cats with eye tumors. 

• If your cat has a serious injury to their eye, talk to your vet about their risk for a post-traumatic ocular sarcoma and consider an enucleation surgery. 

• Eliminate your cat’s exposure to environmental toxins such as cigarette smoke and chemicals. 

• Prevent your cat from interacting with community cats who are more likely to carry viruses. 

• Watch your cat’s eyes closely for any changes. Quick intervention is often ideal for best treatment outcomes.