Cancer in Cats: Symptoms and Treatment

Dr. Jason Gagné, DVM, DACVIM
By Dr. Jason Gagné, DVM, DACVIM
Updated: 5/20/20242-4 minutes
Red cat

Cancer in cats is less common than in dogs, but when it occurs it’s more likely to be fatal. Additionally, cats are good at hiding their pain, which can make detecting cancer early difficult.

If you suspect your cat has this illness, contact your veterinarian as soon as possible. To help you provide the best care possible, here’s what you should know about cat cancer symptoms and treatments.

What is a Tumor in Cats & When is it Cancerous?

A tumor is an uncontrolled growth of cells that forms a lump. Sometimes these lumps can disrupt organ function. When this happens, the consequences can be serious for your pet.

There are two types of tumors: benign and malignant.

Benign tumors aren’t life-threatening, don’t spread, and can be straightforward to treat, depending on their location.

Malignant tumors are cancerous and may be invasive as they spread throughout the body. These types can be difficult to treat.

Types of Cancer in Cats

It may surprise you to learn that cats can suffer from many of the same cancers as humans. A few of the most common types of cancer in cats are as follows:

  • Cat lymphoma – cancer related to a type of white blood cell called the lymphocyte.
  • Feline leukemia – cancer of your cat’s bone marrow.
  • Cat breast cancer – also called “mammary gland tumors,” these start as a small lump in your cat’s mammary gland
  • Cat squamous cell carcinoma – cat skin cancer that usually appears as a lump or white patch and may look similar to other cat skin problems.
  • Feline soft tissue sarcoma – cancer that can affect your cat’s skin, fat, connective tissues, nerves and small blood vessels below the skin.

Cat Cancer Symptoms

Remember, cancer in cats can be difficult to detect. Unless the illness materializes as a physical lump and you can see or feel it, you’ll have to pay close attention to your feline’s behavior and mood instead. Additionally, a lot of cat cancer symptoms can be signs of other diseases or illnesses too. Your veterinarian will need to make a diagnosis.

Some cat cancer symptoms you should watch for are:

  • Weight loss. Often cats with cancer will have a poor appetite and they may lose a lot of weight.
  • Difficulty chewing. This could be a sign of cat mouth cancer. It’s important to regularly check and clean your feline’s teeth to look for any possible mouth problems.
  • Digestive upset. Cancer in cats can affect the digestive system, causing vomiting and diarrhea.
  • Lethargy. If your cat is hiding more than usual or spending more time sleeping, it could be a sign they’re feeling unwell.
  • Growths and lesions. Bumps, lumps or sores that don’t seem to heal may be a sign of cat skin cancer.
  • Difficulty breathing. Sometimes cancer in cats can cause inflammation and the buildup of fluid in or around their lungs.

If your cat displays any cancer signs, contact your veterinarian. Even if they don’t have cancer, symptoms could be related to a health condition that needs treatment.

Diagnosing Cancer in Cats

Unfortunately, cancer in cats can’t be identified based on sight alone, so your veterinarian will need to do further tests.

Blood samples are typically taken in order to detect the effects of the cancer and to rule out other diseases.

X-rays and ultrasound or MRI may also be conducted to identify the location and size of the tumor. Then, a biopsy by an experienced pathologist can allow them to examine the microscopic tissues of the tumor, and determine whether or not it’s cancerous.

Cat Cancer Treatment

The treatment for cancer in cats will depend on the cancer type. Your veterinarian can recommend based on the specific disease and your individual pet.

For superficial tumors such as squamous cell carcinoma, soft tissue sarcomas and mammary tumors, surgery may be required and sometimes chemotherapy too.

While this treatment may sound scary, it’s less extreme than chemotherapy for humans. It’s usually administered via injections and if your cat appears to experience discomfort during the treatment, it can be stopped.

Additionally, radiation therapy may also be recommended.

The best way to ensure that your cat makes a full recovery is to catch cancer early. Make sure you take your pet for regular veterinarian check-ups, and keep an eye on their behavior and mood. If they display any cancer symptoms, contact your veterinarian as soon as possible.

For more feline health tips, check out our cat health articles for advice from our experts.

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