While cancer in cats is not as common as it in dogs, it is still one of the leading causes of death in older cats.  According to the Animal Cancer Foundation, 6 million cats will be diagnosed with cancer in the United States along. And because cats are masters at masking illness, it is often harder to detect.  Cancer used to be a death sentence for cats, but recent advances in feline cancer research have made treatment possible in many cases.  Just like with human cancers, early detection is key to successfully treating feline cancers.

Common cancers in cats

One of the most common forms of cancer in cats is lymphoma. Other frequently seen cancers are oral squamous carcinomas, similar to what people get.   Fibrosarcomas, or soft tissue sarcomas, are tumors developing in muscle or in the connective tissue of the body.  These are generally associated with injections and vaccinations.  Other forms of cancer are less common, but they do occur in cats:  lung tumors, brain tumors, nasal tumors, liver tumors.  There are fewer incidences of mammary tumors (yes, cats can get breast cancer, too) since more cats are spayed and spaying is one of the best ways to prevent this particular cancer.

Symptoms of feline cancer

People and cats both show similar symptoms when it comes to cancer:

  • Lumps, especially lumps that seem to be getting bigger
  • Sores that don’t heal
  • Changes in bowel or bladder habits
  • Unexplained bleeding or a strange discharge from any body opening
  • Loss of appetite and weight loss
  • Breathing problems
  • Lameness or stiffness that persists over a period of time
  • Bad odor
  • Having trouble eating or swallowing food

If you notice your cat showing any of these symptoms, take him to your veterinarian for a thorough examination.


Diagnosis will vary, depending on the presenting symptoms.  An exam will most likely include a complete blood chemistry, blood count, and urinalysis.  Your veterinarian may take x-rays, perform an ultrasound, and take tissue biopsies.  Depending on where the biopsies are taken from, this may require sedation, or full anesthesia.  Biopsies will be reviewed by a veterinary pathologist to determine the type of cancer.


Treatment options for cats are almost as varied as treatment options for human cancers, and will depend on the type of cancer.  Surgery is the most common treatment for any lumps or growths that need to be removed.  In some cases, surgery can be curative.  Other cancers may require chemotherapy or radiation.  Cats tend to tolerate chemotherapy much better than people, and can have good quality of life for many months and sometimes even years following treatment.  Radiation therapy may be used for tumors that can’t be removed.  This is a more stressful therapy for cats, since it will require sedation or anesthesia for each treatment.


There isn’t as much research into the causes of feline cancer as there is on the human side, but I don’t think it’s much of a leap to assume that some of the same environmental toxins that cause cancer in humans also cause cancers in our cats.  There have been some studies looking at secondhand smoke and feline cancers.  Vaccinations and other injections have been proven to be responsible for fibrosarcomas, and these findings have led to changing vaccine protocols for cats.


While some cancers are caused by genetic mutations, there are still things cat owners can do to lessen the likelihood that their cats get the disease.

A wholesome, species-appropriate, meat-based diet is one of the most important foundations for preventing cancer, or any other health problems in cats.  A balanced grain-free raw meat or canned diet provides the best nutrition for your cat.  As obligate carnivores, cats do not need carbohydrates in their diet.  In fact, commercial dry cat foods have been linked to many of the degenerative diseases we’re seeing in cats such as diabetes, kidney failure, and inflammatory bowel disease.  The latter is often a precursor for intestinal lymphoma.  The one best thing you can do for your cat’s health is to eliminate all dry food from his diet.

Environmental toxins and stressors are also linked to cancer in humans, and probably cause cancers in cats.  Avoid exposure to commercial cleaning products and use natural products instead.  Make sure your cat always has pure (bottled or distilled) water available.  Most municipal water systems are contaminated with anything from heavy metals to chlorine.  Don’t use chemical flea and tick products on your pets, use natural alternatives instead.  Minimize vaccinations, and if your cat already has cancer, do not vaccinate the cat at all.

Cancer is a devastating disease, but early detection, combined with ever increasing treatment options, makes it possible for cats to continue to live with good quality of life.

You may also enjoy reading:

In memory of Sophia: cat owner runs half marathon to benefit cancer research

Feline nutrition: who bears the responsibility?

Photo is of Feebee, my first cat.  I lost him to lymphoma two days before his sixteenth birthday.


14 Comments on Cats and Cancer

  1. Thank you for this article. I recently bought cat 2 yrs old unspayed. She weaned a litter prior to my getting her. I’m really struggling with whether I should spay her or not. I’m currently transitioning from a kibble diet to wet canned and hopefully raw in the future. I’m wondering if a dry kibble diet is responsible for mammory tumors or the ovarian cyst I see mentioned. I’m feeling horrible about this type of operation, but don’t plan on her breeding again, and worry if I don’t spay, will I cause her to get these cancers or cysts in the future. Thank you for your time

  2. My 15-year old cat Sasha was diagnosed with lymphoma just 3 days ago, after an ultrasound my local vet had recommended because Sasha has been losing weight for almost a year even though his appetite kept increasing. He appeared normal in all other respects, so I wasn’t too concerned. I realize now that he must have been sick for some time, he’s eating so much because he’s not getting the nutrients he needs, and also drinks a lot for the same reason. I’m prepared to let him go, I just wish I knew when he starts to feel pain, an easy passing is the last gift I can give him (I’ll have a euthanasia vet come to my home to put Sasha to sleep gently with no stress).

  3. I lost my two favorite cats, my boys Nutmeg and Dudley, separately in 1997 and 2010 to lymposarcoma. Wish I’d known then about the connection to dry cat food, particularly in Dudley’s case. He was a very special little guy and will forever be missed; it will be a year on October 30th. I’m going to switch to all natural dry food.

    • I’m so sorry about Nutmeg and Dudley, Nancy.

      I’d encourage you to go one step further and eliminate dry food altogether. If you look around the feline nutrition section on this site, you’ll find a few articles on the “why” and “how.”

  4. Wonderful article. My cat Fluffy just died of Cancer. He ate a lot towards the end and it was in his bowel, went undetected until it was too late. He lived a long life and the vet said that it was an aggressive form that would grow right back if we treated it. Fluffy was starting to “shut down”, and there wasn’t much else the vet could to so we put him down, it was the hardest decision I’ve ever made in my life. Rest in Peace, my sweet old boy. I miss you and if I could’ve kept you going, I would’ve.

  5. Wonderful and informative post. We just went through this with Gum Drop. Her only symptom was a small knot that began to enlarge. The vet called it breast cancer in cats. She was able to do surgery and remove all of it without any problems because we caught it early enough. We’ll have to continuously check her for new knots but the vet didn’t think we’d have any more problems. Gum Drop is recovery well and we were very lucky. Thanks for getting the word out to other cat owners.

    Thoughts in Progress

    • I’m so glad to hear Gum Drop is recovering well, and that the cancer was found early on. Lots of good wishes going out to her for a continued complete recovery!

  6. That is a great post with some good information. I think the older cat I have here has cancer on her ears and now I am beginning to suspect in her mouth too. She has a lot of trouble chewing. I was going to send her to the bridge today but I have her some juice out of some cat food and she ate a bunch of that, so going to wait a day or two. She has lost a lot of weight too. She has a bunch of other problems too.
    Thanks for all that good information. I am so glad to hear that they are doing some research on cancer in cats.

    • I’m so sorry about your kitty, Marg. It sounds like she’s not quite ready to give up, though – sending lots of good thoughts and healing energy to her.

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