Melanoma in Cats: Causes, Treatment, and More

|8 min read

A cat's eyes and fur are their most prominent features, but weirdly, the cells that determine the color of our cat's eyes and coat can actually be quite troublesome. Melanocytes are a type of cell that can cause melanoma in cats if they grow out of proportion.

In addition to the appearance of dark spots or tumors on the skin, cat melanoma can also form in the eyes or mouth. Melanoma is considered the most dangerous type of skin cancer in humans just because it spreads aggressively. But it's pretty rare in cats.

Melanoma in cats can develop in different areas of a cat's body, such as the skin, oral cavity, and eyes. These growths may be either benign or malignant melanomas. It is a generally uncommon condition, and it is usually seen in older cats.

In this article, we delve into the topic of feline melanoma, exploring the causes, symptoms, and available treatment options.

Understanding this condition is crucial for cat owners and veterinarians, as early detection can significantly increase the chances of fruitful treatment and a better quality of life for our feline friends.

Different Types of Melanoma in Cats

Melanoma can appear wherever there are melanocytes (pigment-producing cells) in a cat's body. How harmful it is depends on where it appears.

Some really invasive melanomas can develop in certain areas. These tumors not only cause problems where they grow but can also quickly spread to important organs like the lungs and liver. The most severe melanomas in cats often happen in the mouth, on the lips, toes, or paws, and in the eye.

In cats, there are three kinds of melanoma, depending on the tumor location - ocular, oral, and skin.

  1. Ocular melanoma

    This form of melanoma affects the eyes and is usually more harmful compared to those found in the mouth or skin. It's the most frequent kind of feline melanoma, and it happens more often in cats than in dogs. This can be a particularly invasive melanoma in cats.

  2. Oral melanoma

    Melanomas growing in the mouth are very harmful tumors. These tumors typically look like cauliflower due to their uneven surface.

    They can appear anywhere in the mouth, like the palate, tongue, and tonsils. They can damage tissues in the mouth and rapidly extend to other body parts, which makes them extremely dangerous.

  3. Dermal melanoma

    The majority of skin melanomas are not harmful and are known as melanocytomas. These growths typically appear on parts of the body covered with skin.

    However, not all pigmented skin growths are harmless. Some melanomas that seem harmless have turned out to be harmful after close examination under a microscope. That's why it's crucial to inform your vet about any pigmented growth on your cat's skin.

Symptoms of Melanoma in Cats

Detecting melanoma early on is crucial for effective treatment, so it's important to be aware of potential signs:

In the case of skin melanoma, you might notice a lump or see a flat change in color on the skin. It can lead to cat skin cancer.

For oral melanoma, your cat might drool more than usual, have bad breath, or struggle with eating. This could include chewing on one side, tilting their head while eating, or preferring soft foods. Some oral melanomas may appear black, but others may lack pigment, known as amelanotic melanomas.

In ocular melanoma in cats, the colored part of the eye (iris) might look darker. However, freckles can also occur, so a vet or a veterinary eye specialist should determine if a benign condition is causing the discoloration.

Any abnormal growths on the skin, in the mouth, or eyes should prompt a visit to the vet for a closer look.

Causes of Melanoma in Cats

The exact reason for melanoma has yet to be fully understood. It is thought to result from a combination of genetic factors and environmental influences.

Here, we explore possible causes and factors that may increase the risk factors for melanoma in cats.

  1. Genetic influence

    Certain cats may be prone to melanoma due to their genetics, similar to humans. These genetic tendencies can lead to cell mutations, causing uncontrolled growth and the eventual formation of tumors.

  2. Sunlight Exposure

    Just like in humans, exposure to sunlight is a major factor that increases the risk of skin melanoma in different species. Cats, especially those with light-colored or white fur and those spending considerable time outdoors, face a higher likelihood of sun-related skin damage, potentially increasing their risk of developing skin melanomas.

  3. Inflammation or Irritation

    Continuous inflammation or irritation in the mouth area could play a role in the development of oral melanoma in cats. This persistent irritation may be linked to dental issues, exposure to tobacco smoke, or other chronic oral conditions.

  4. Age

    Melanoma is more commonly seen in older cats, as just like in humans, the likelihood of developing most cancers increases with age.

  5. Viral infections

    Some early studies suggest that certain viruses might be linked to a higher chance of getting melanoma. But, we need more research to make sure if this is true.

Stages of Melanoma in Cats

Staging is a crucial step in figuring out and treating harmful melanoma in cats. It helps predict what might happen based on how far the tumor has spread. To see if the tumor has spread to other parts of the body, vets use chest X-rays, check lymph nodes, and do abdominal ultrasound exams.

The tumor's size is super important for predicting what might happen. In pets, vets use a staging system to figure out how bad the cancer is. These stages are:

  • Stage I

    The tumor is small, measuring less than 2 centimeters (cm) in diameter. This indicates the early stages of melanoma.

  • Stage II

    The tumor is between 2 to 4 centimeters in diameter.

  • Stage III

    The tumor is 4 centimeters or larger, and there may or may not be involvement of local lymph nodes.

  • Stage IV

    There are signs of the tumor spreading to distant parts of the body.

Diagnosing Melanoma in Cat

Tests to check if a cat has malignant melanoma are similar to those used for other types of cancer.

Your cat's behavior can give hints about the cancer progressing and if it's affecting the body's systems. A physical examination can show if there's a lump and how big it is, and vets often check for any swollen lymph nodes, even during regular check-ups.

Blood work and urine tests help check your pet's overall health and organ function. Chest X-rays from three different angles and maybe an ultrasound of the belly can be done to see if the cancer has spread to the lungs or liver.

Depending on where the lump is and if it's easy to reach, a fine needle aspiration might be done to take a sample for further lab testing.

Finally, a biopsy, taking a piece of the actual lump, may be necessary to get a definite diagnosis.

How to Treat Melanoma?

Different types of melanoma in cats need different ways to treat them. 

  • Surgery

    If the tumor is easy to reach and your cat is healthy enough, surgical removal is often the best choice. In surgery, the goal is to remove the tumor with clean edges, meaning the part taken out along with the tumor doesn't have any cancer.

    For a benign skin tumor, taking it out might make your cat all better. But if it's a harmful tumor, the doctors will check how bad it is to decide what to do next.

    The problem with the surgical removal of a harmful tumor is that the cancer might come back in a few months. This is why, after surgery, they might suggest radiation to lower the chance of the cancer coming back.

  • Eye Removal

    Enucleation is a special kind of surgery. It's done when a cat has ocular melanoma, which means surgical removal of a cat's eyeball. It is done if the cancer cells have spread into blood vessels.

    A vet eye specialist called a veterinary ophthalmologist, should be asked for advice before this procedure because it needs expert advice and special skills.

  • Radiation Treatment

    Radiation might be the main treatment or used alongside surgery. It is a way to eliminate cancer cells by aiming high-energy particles at the tumor. The goal is to damage the cancer while trying to keep the nearby healthy parts safe.

    There are two main types: regular radiation therapy (CFRT) and a more advanced one called stereotactic radiation (SRS). SRS uses stronger radiation with more precision, so fewer sessions are needed—just one to three, compared to 16 to 18 for regular radiation.

    If surgery isn't an option and radiation is the best choice, then stereotactic radiation is done for cats with melanoma.

  • Chemotherapy

    Chemotherapy is usually not the way to treat melanoma in cats. But if surgery can't remove the tumor, or if it didn't fully work, chemo might be suggested to help improve the cat's quality of life. It could be considered for really serious melanoma cases, as chemo has its own gruesome side effects.

  • Melanoma Vaccine

    Sometimes, a special melanoma vaccine that's meant to fight cancer cells might be given to treat the cat with melanoma.

    However, a vet who specializes in cancer for pets should decide if it's right for the cat, considering the type of cancer, its stage, and other influencing factors.

Final Words!

To sum up, watching out for melanoma in cats is important for their health. Even though melanoma is not common in cats, it can be severe, so catching it early and getting the right treatment is key. Otherwise, it can result in tumor spread. There are different types of melanoma, and each needs its own approach, like surgery or radiation.

Knowing the signs, like changes in skin color or strange behaviors, helps get quick help from the vet. Older cats, in particular, should have regular check-ups to catch any issues early. The treatment options, like surgery and radiation, aim to remove or treat the cancer.

Because of potential genetic factors, stopping melanoma in cats can be tricky. But there are things you can do, like reducing sun exposure, taking care of your cat's oral health, and regularly going to the vet for check-ups to catch any issues early—changes in the skin, eyes, or how your cat acts could be signs of skin cancer. If you notice anything different, it's vital to talk to the vet right away.

It's vital to know that it is a team effort between cat owners and vets to make sure our feline friends get the care they need. We can keep our beloved cats healthy and happy by being watchful, getting help early, and working with the vet.

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