How to Recognize Skin Cancer in Cats

Co-authored by Jamie Freyer, DVM and Devin McSween

Last Updated: February 12, 2024 Fact Checked

When it comes to skin cancer, a cat's best friends are their hairy coat and pigmented skin. Their dense fur shields their skin from UV rays and acts like a permanent sunscreen, which means that cats are less prone to skin cancer than people or thin-furred animals. However, cats can still get skin cancer. The most common feline skin cancer is squamous cell carcinoma (SCC). If you have a cat, you should be on the lookout for signs that they have skin cancer so that it can be treated as quickly as possible.^{[1]
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Part 1

Part 1 of 3:

Finding Lumps on Your Cat

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According to veterinarian Jamie Freyer, "any strange bump or lump that shows up suddenly is something you want to look into."^{[2]
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Jamie Freyer, DVM
Licensed Veterinarian

Expert Interview. 8 October 2021.} Skin cancer usually creates an area on the skin that is discolored and raised. When playing with your cat or cuddling up with them, take the time to look over their body for areas of discolored skin. Also look for areas where the cat's fur is out of place, perhaps due to a growth underneath the skin.^{[3]
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Jamie Freyer, DVM
Licensed Veterinarian

Expert Interview. 8 October 2021.}
2
Feel your cat's body for lumps. Because cats are covered in so much fur, it's also important to feel your cat's body for signs of skin cancer. Feel for lumps and bumps on the skin in areas that are covered with fur as well as areas that are less covered, like the nose and ears.^{[5]
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Jamie Freyer, DVM
Licensed Veterinarian

Expert Interview. 8 October 2021.}
- While skin cancer is often related to sun exposure, and thus more commonly occurs in areas with less fur, some kinds of skin cancer are genetic and not related to sun exposure at all. Cats tend to be less likely than other animals to get skin cancer that is not UV-triggered, such as mast cell tumors.
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Be especially diligent with looking for skin cancer on white cats. Squamous cell carcinoma (SCC) has a higher risk of developing in white and light-colored cats and most commonly affects their noses, eyelids, and ears. This is often a direct result of UV exposure, which thin-furred cats with less skin pigment are more vulnerable to. A sun-loving white cat is more prone to developing SCC, so regularly look for signs of this disease on white cats.^{[6]
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- Indeed, if the cat has one black ear and one white, the white ear is more likely to be affected by SCC.
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Have all lumps assessed by a veterinarian. Some signs related to skin cancer should spark your immediate concern, such as rapid lump growth, redness, or ulceration (the lump becomes an open wound and has difficulty healing). Veterinarian Jamie Freyer stresses that "there is no guarantee a small, slow-growing lump is harmless or harmful." This is why it is important to have all lumps assessed by a veterinarian.^{[7]
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Jamie Freyer, DVM
Licensed Veterinarian

Expert Interview. 8 October 2021.}
- Some aggressive tumors are great mimics and take on the characteristics of innocent lumps, such as being superficial or slow-growing. However, at some point in the future, they may become aggressive.
- It is difficult to distinguish a harmless, benign skin lump from a malignant, cancerous one just by looking at it with the naked eye. The only way to tell for sure whether or not a lump is harmful is for your veterinarian to collect some of its cells (via needle aspiration) or do a biopsy to take some of the tissue and send either sample to the lab.^{[8]
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  Jamie Freyer, DVM
  Licensed Veterinarian
  
  Expert Interview. 8 October 2021.}

Part 2

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Assessing a Lump

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1
Check the growth rate of a lump. Skin lumps are less likely to be malignant and cancerous if they are slow-growing, meaning they don’t perceptibly change from one month to the next. Fast-growing lumps are called aggressive tumors. These often have the ability to spread to other parts of your cat's body. These types of lumps grow so quickly that you can often see a change from week to week.^{[9]
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- When you first find a lump, measure it with a ruler and record the measurement. Repeat the measuring process every week so that you can establish if the lump is changing or not.
A lump that sits discretely on the surface of the skin, has a definite border, and is not infiltrating the surrounding tissues is more likely to be a wart, cyst, or harmless skin mass than skin cancer. Skin cancer is more often embedded in the skin and you can feel the mass under the skin.^{[10]
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Black pigment in a pale-skinned animal is often a warning sign when it comes to skin cancer. Dark pigment is frequently associated with more serious cancers such as malignant melanoma, thus a dark-colored lump must never be ignored.^{[11]
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Skin cancer can cause irritation, which means that your cat might scratch, rub, lick, or chew on the lump to relieve that irritation. Some of the more serious cancers, such as mast cell cancer, contain histamine granules that can make the lump very itchy.^{[12]
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Monitor for any inflammation or ulceration. Cancerous lumps tend to look inflamed, which means that the skin looks pinker than the surrounding tissue. When you first find a lump, look at the tissue surrounding it and see if that area is red or inflamed.^{[13]
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- In the early stages of squamous cell carcinoma, non-pigmented skin can become inflamed and look darker pink than the surrounding skin. The skin might take on a scaly appearance that looks similar to ringworm.
- Ulceration means that the lump breaks open and becomes a wound. If you notice this, seek medical help for your cat.
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Look for irregularly shaped lumps. Cancerous lumps often take on irregular shapes. This means that they lack a defined, round shape, as regular lumps are generally round.^{[14]
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- The lump instead infiltrates deeply into the skin, so that the skin appears “glued” down to the tissue beneath.
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See if the skin becomes darker in color. With squamous cell carcinoma, continuing to lie in the sun can cause your cat’s inflamed areas to take on an angry red color. There is also a chance that the skin will begin to erode; if this happens, ulcers may begin to form.^{[15]
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- If the cancer affects an ear, the edge of the ear may become irregular in shape, almost as if small bites have been taken out of it.

Part 3

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Seeking a Medical Diagnosis

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1
Protect your cat from the sun if you spot signs of skin cancer. Apply a pet-friendly sunblock with an SPF of at least 15 to your cat’s sensitive skin until you can take them to see a vet. You can also keep your cat indoors on sunny days or during peak sun exposure (10 AM to 2 PM) to prevent them from lounging in the sun. If they’re an indoor cat, close the shades to further block UV rays.^{[16]
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- Only use sunscreen that is made specifically for cats and animals. Regular sunscreen can contain ingredients that are harmful or toxic to cats.
- Always check the sunscreen’s ingredients and do not use a lotion that contains octyl salicylate and zinc. These are not good for cats, as they may swallow the product and be exposed to potentially toxic effects while grooming.
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Have your cat seen by a vet. It is unwise to make assumptions about skin lumps on cats as you can’t visually tell whether they’re cancerous or not. Skin cancer is rare, but it can be serious. With this in mind, if you find a lump on your cat, get it checked by a veterinarian.^{[17]
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- Call your veterinary office and tell them what you found. Make an appointment to have your cat seen as soon as possible so that if there is a problem, you can begin treatment right away.
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Have a fine needle aspiration done.^{[18]
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Jamie Freyer, DVM
Licensed Veterinarian

Expert Interview. 8 October 2021.} A fine needle aspirate (FNA) involves taking a small sample of cells from the lump with a hypodermic needle. It allows the veterinarian to inspect the cells for signs of cancerous growth. However, it does run the risk of missing cancerous cells due to the small size of the sample.^{[19]
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- This is a non-invasive procedure that is done while your cat is fully conscious. Most cats tolerate the process well.
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Get a biopsy done. A biopsy involves removing a wedge of tissue from the lump and sending it to be assessed at a lab. If the lump is easily removed, then an excisional biopsy may be performed. This means the vet will surgically remove the lump and will send a portion away for histology at a lab.^{[20]
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Jamie Freyer, DVM
Licensed Veterinarian

Expert Interview. 8 October 2021.}
- A histology test determines if the lump is cancerous.

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Is a lump always cancer?

Jamie Freyer, DVM
Licensed Veterinarian
Dr. Jamie Freyer is a Licensed Doctor of Veterinary Medicine based in Washington. With over ten years of experience in clinical practice and industry, she specializes in veterinary medicine and surgery, animal behavior, and animal genetics. Dr. Freyer holds a BS in Life Science from The University of Portland and a DVM from Oregon State University.

Jamie Freyer, DVM

Licensed Veterinarian

Expert Answer

Not necessarily! Lumps can also be benign, fatty, or caused by abscess. Abscesses are especially common in outdoor cats, and tend to form after they're bit, poked, or roughed up in some way.

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Treatment for skin cancer typically involves surgically removing the tumor or tumors. If that isn’t possible, your veterinarian might recommend chemotherapy or radiation.^{[21]
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Cats are not as prone to skin cancer as other species, but if they do develop a lump it can be serious. White cats are especially at risk of squamous cell carcinoma because of the lack of pigment in their skin. If your cat has a skin lump, always get it checked by a veterinarian.^{[22]
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