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Cancer in Cats: What You Should Know About Feline Cancer

Darlene Norris is a long-time pet lover. She has worked as a vet assistant and draws on this experience when she writes her articles.

If your kitty has a white nose or white ears, you should keep him indoors during the afternoon to prevent feline skin cancer.

If your kitty has a white nose or white ears, you should keep him indoors during the afternoon to prevent feline skin cancer.

What Is Cancer?

Cancer is unrestrained cell growth. Every cell in your body wears out sooner or later. As these old cells die off, new ones are produced to replace them. Normally, new cell growth is regulated by the body, but sometimes a switch gets turned on which allows cells to reproduce uncontrollably. This leads to the growth of tumors—a group of abnormal cells clumped together to form a mass.

You may hear different words used to describe cancer. "Neoplasia" means new growth, and "neoplasm" means "tumor." Tumors in cats may be benign, which means they don't spread to other organs. A benign tumor, however, can still grow into the surrounding areas and cause problems.

Malignant tumors can grow into nearby areas, damaging or destroying normal cells. Often surgery to remove them is difficult or impossible when they have grown into one of your cat's organs. Malignant tumors often spread throughout the body by means of the lymphatic system (carcinomas) or the bloodstream (sarcomas). When a malignant tumor spreads, this process is called "metastasis."

Cancer can occur anywhere in your cat's body. Carcinomas form on epithelial cells that line organs and glands. Sarcomas form on bones and other connective tissues.

What Are the Most Common Kinds of Feline Cancer?

Cats can get many different kinds of cancer, but the ones that most commonly affect kitties are lymphosarcoma, squamous cell carcinoma, and mammary (breast) cancer.


Lymphosarcoma in cats may be found in kitties of any age. It used to be more common in younger cats who were infected with feline leukemia. But now that more cats are being vaccinated, fewer younger cats are being affected.

Squamous Cell Carcinoma

Tumors may also be caused by feline squamous cell carcinoma (SCC), especially skin tumors. White cats are more susceptible to this type of skin cancer, since they don't have pigment to protect their ears from the sun's rays. These tumors usually show up around the age of 12. With treatment, the outlook is good for most cats with skin cancer.

Oral squamous cell carcinoma is often seen in cats. Swelling of the face or jaw, bleeding from the mouth, and weight loss are symptoms to watch for. Sadly, this type of cancer is often not discovered until it's already in advanced stages when treatment options are few.

Breast Cancer

Feline breast cancer is often seen in older females. Siamese cats are especially prone to mammary tumors. These tumors are usually malignant, and they usually spread quickly to other glands in the body, and also to the lungs. When this happens, the outlook is not good.

Oral Squamous Cell Carcinoma in Cats

Cancer in Cats: What Causes It?

Feline cancer is often seen in older animals. Why? There are a couple of reasons. As a cat ages, the immune system isn't as strong as it used to be. It's thought that the immune system helps to get rid of cells that have mutated. A weakened immune system might let more of these mutated cells escape, possibly leading to cancer.

Another thought is that an older cat has been exposed to more carcinogens, or cancer-causing chemicals, in the environment. The effect over the years is cumulative, which can lead to cancer as the cat gets older.

Certain viruses, like the feline leukemia virus, have been tied to feline lymphoma.

Can Injuries Cause Cancer?

Bumps and bruises don't cause cancer, so don't worry if your cat is running into the walls or furniture while playing or chasing another cat around. However, a traumatic injury like a broken bone can lead to cancer, even years after the injury occurred. Areas around implants like pins or plates may have a higher likelihood of developing sarcomas later in life. Some researchers think traumatic injuries cause chronic inflammation, which may lead to cancerous tumors as time passes.

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Vaccinations have also been implicated in sarcoma development. Vets have noticed sarcomas forming at vaccination sites since the early 1990s. Try not to over-vaccinate your pets.

Cancer in Cats Is Linked to Poor Oral Hygiene

Cats who eat canned food should have regular teeth cleanings to prevent feline oral squamous cell carcinoma.

Cats who eat canned food should have regular teeth cleanings to prevent feline oral squamous cell carcinoma.

Risk Factors for Oral Squamous Cell Carcinoma

There are several risk factors for this type of cancer. They include flea collars, feeding canned food, and exposing white cats to too much sunlight.

Can Flea Collars Cause Cancer in Cats?

It's possible. One study found a 5-fold increase in oral squamous cell carcinoma in cats who wore flea collars. These collars have a high concentration of pesticides. Plus they're very close to the mouth. We probably should rethink using flea collars on our pets.

Apparently flea shampoo doesn't increase the cancer risk. This is probably because it's washed off the pet's coat. Cats whose owners bathed them using flea shampoo showed a much lower incidence of carcinoma, probably because the cat isn't licking the chemicals off his fur. Bathing a cat is a challenge, but it may be better than using flea collars.

Feline Cancer Linked to Canned Cat Food

Cats who are fed canned food may be at a higher risk of oral cancer than those who are fed dry food. Researchers don't seem to be sure why. They think nutritional differences in canned and dry food could be the cause. Another explanation is that cats who are fed canned food have more tartar buildup than those fed dry food. Poor oral hygiene in humans is linked to oral cancer, so perhaps there is a link.

Skin Cancer in White Cats Caused by Sunlight

White cats are especially prone to skin cancer on the eyelids, the tip of the nose, and the tips of the ears. Why? There is little or no hair in these areas, and white cats have no pigmentation to protect the skin from the sun.

If you have a white cat, it's recommended that you keep your kitty indoors between noon and four o'clock in the afternoon to minimize their exposure to ultraviolet radiation.

Second-Hand Smoke Increases the Risk of Cancer in Cats

Smoking around your cat can increase the risk of him developing cancer by five times.

Smoking around your cat can increase the risk of him developing cancer by five times.

Second-Hand Cigarette Smoke Is the Biggest Risk Factor for Feline Cancer

Kitties who live in a home where somebody smokes have a much higher risk of developing feline lymphoma, a cancer common among cats.

What exactly is second-hand smoke? It's the smoke that's exhaled into the air by a smoker. It's also smoke that comes directly from a burning cigarette or cigar. If you and your cat live with a smoker, second-hand smoke can cause health problems for both you and your cat. But, have you ever heard of third-hand smoke? It's what's left on clothes, furniture, walls, skin, and fur, even after the air is clear of smoke. It can be seen as a yellowish residue that builds up over time on walls and furniture—this is what your cat licks off his or her fur. Environmental tobacco smoke, or ETS, is the combination of second and third-hand smoke.

Smoking Impacts Your Cat's Health

Cigarette smoke contains more than 4000 chemicals, including carbon monoxide, formaldehyde, benzene, chromium, nickel, vinyl chloride and arsenic. Since cats are a lot smaller than people, it only stands to reason that it would take much less exposure to these chemicals to cause health problems for them.

We tend to forget that since our pets live with us, they're exposed to the same environmental toxins we are. Inside cats often fare worse because they don't get to leave the house during the day like their owners do. Felines are doubly exposed to carcinogens in tobacco smoke. Not only do they inhale the smoke, but they lick the particulates from the smoke off of their fur as they groom themselves.

Some people think that if they smoke by an exhaust fan in the kitchen, it will pull all the smoke out of the house. This isn't true. Many carcinogens found in cigarette smoke are in the form of gas, which can't be completely removed by ventilation fans. It can take hours to clear the house of the smoke from one cigarette. In the meantime, your kitty is exposed to everything in the smoke.

Feline cancer isn't the only risk your kitty faces from tobacco smoke. Your cat may be more susceptible to bronchitis, sinus infections, pneumonia, heart failure, lung cancer, feline asthma and eye irritation.

Studies Document the Dangers of Environmental Tobacco Smoke for Cats

A study at Tufts School of Veterinary Medicine indicates that felines exposed to cigarette smoke have a significantly higher risk for feline lymphoma than do cats in non-smoking homes.

80 cats who were suffering from cat lymphoma, and 100 who had kidney failure, were followed over seven years:

  • Cats exposed to environmental tobacco smoke had more than twice the risk of developing feline lymphoma than did cats in non-smoking households.
  • The risk of tumors in cats increased to three times higher if the kitty lived in a home with a smoker for five years.
  • If a person smoked a pack a day or more of cigarettes, the risk of cancer in cats increased three times.
  • If two or more smokers were present, the risk was four times higher.

Newer studies have shown that feline oral squamous cell carcinoma is much more common in cats living in homes with smokers. This is probably because they lick particulates from smoke off their fur, as mentioned above.

How Can You Lessen Your Kitty's Risk?

The best thing you can do for both yourself and your feline friend is to stop smoking. If you can't stop, then go outside to smoke. This can help to lessen the risk, but doesn't entirely eliminate it. Studies have shown ETS levels in the home are still five to seven times higher than in non-smoking households, even when someone smokes outdoors.

  • You can also set aside smoke-free rooms in your home for your pets. Brush your furry friend regularly to remove any residue from his fur.
  • An air purifier may remove some of the toxins from the air your kitty breathes. You may want to give your pet vitamin C and antioxidants to reduce his cancer risk.

Our kitties depend on us to provide safe homes for them. Protecting our pets from the dangers of environmental tobacco smoke is one of the best things we can do for them.

Know the Warning Signs of Feline Cancer

New treatments for cancer in cats are being developed all the time, but any treatment is most successful when the cancer is found in its earliest stages. Anyone who lives with a kitty should know the warning signs of cancer in felines:

  • Sudden weight loss
  • Difficulty chewing and swallowing food
  • Bleeding from the mouth or any other part of the body
  • Unusual lumps or bumps
  • Vomiting or diarrhea
  • Bad breath

Sick cats tend to hide themselves away. If your formerly friendly, outgoing pet suddenly turns into a recluse or becomes grouchy, he may be ill. Take him to the vet for a check-up as soon as you can.


This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


Dina on October 27, 2012:

My cat also has cancer. He has spindle cell carcinoma and it's malignnt and was spreading all over his body.He had to have his leg amputated to stop the tumors spreading. But even with hie leg amputated, the tumors are spreading and are infecting his lugns and his breathing. Doctor says it's time to put him to sleep afgter the X-RAYS.

cathy thomas on January 24, 2012:

my 9 year old sweetheart cassie has a cancerous tumor on her chest. it started the size of a pea.but has grown the size of a small ball in only four weeks. she cant breath good and is very lethargic just a couple weeks ago she was just fine.there is nothing we can do and i feel helpless.she was actually my husbands cat.he passed away last year in an accident. she is all i have left of this is extremely hard.god bless my kitty she will be with her daddy.

pennie hansen pickles] on December 10, 2011:

I hear ya my cat princess has cancer been very hard but doing the best I can do while she is still alive I love her very she is 8 yrs old she has skin cancer she sneezes a lot feel so bad for her. will be hard when she goes she will be missed [pennie hansen

Alison on October 05, 2011:

Take care Vicki. I fear this is also the time for my 14 year old cat. It is so hard to play god and make this decision even if it is in her best interests.

Rhonda on September 30, 2011:

I'm so sorry, but she is already suffering and you would be showing how much you love her by having her put to sleep. My heart goes out to you.

vicki pallesen on September 12, 2011:

My 15 year old cat is going through the same thing. First diagnosed a month ago with dental problems. 1 month and $1,000 later I am told it is oral cancer with only a couple of weeks left. She cannot eat, she is bleeding from the nose, tounge is hanging out, bad breath and a disfigured face. The end is near and she will probably be but down today.....but it is so hard. I can't put my 15 year old through chemo or radiation. How do you know when it is time?

Jan on August 18, 2011:

My 18 year old had a swollen face and the vet thought it was caused by an abscessed tooth. Yesterday she went in for dental surgery and to have a tumor removed from her eyelid. They discovered that her lower jaw has been destroyed by cancer. All I can do now is love her as long as she is happy and then will have to let her go. It will break my heart.

stephanie on August 13, 2010:

my cat has intestinal cancer and it is very hard. The vet says there is little hope even with treatment. I am keeping her at home until...

I am very worried. It sucks knowing there is nothing you can do.

Cory Zacharia from Miami Beach, Florida on January 04, 2010:

My sweet kittie had a tumor removed from her right nostril this past Christmas Eve (God bless my veterinarian!). The histology came back as a spindle cell sarcoma. We will see a veterinary oncologist this Thursday, but if you have any knowledge about this condition, please let me know. Thank you for these very informative hubs.

wordscribe41 on June 02, 2009:

Great hub, very informative. Sadly it's something we all need to be watching out for, especially in the senior cat. I just lost a kitty to intestinal cancer, the symptom being rapid weight loss. Thanks for the hub.

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