Cancer in Cats

Cancer is not as common in cats as it is in other pets. In fact, a dog is twice as likely to develop cancer over a cat. But, approximately one in five cats will develop cancer.

Cancer is an illness that is not easily identifiable in cats. Cats will often mask their illnesses and this can make it more challenging for a pet owner to identify such a health problem. This, in itself, is a significant problem for cat owners because all-too-often, a cat with cancer doesn’t get diagnosed until late in the disease stage and by then, the aggressive nature of the cancer frequently requires more comprehensive and expensive treatments and surgeries.

The most common types of cancer found in cats are Lymphoma, Squamous Cell Carcinoma, and Fibrosarcoma.

Cancer in Cats

Feline Lymphoma

Of the various types of cancer a cat can develop, lymphoma is the most common. This type of cancer is found in the blood where it is caused by the overproduction of lymphocytes (white blood cells). The majority of lymphoma cases in cats are caused by exposure to and contraction of the feline leukemia virus (FeLV).

Feline lymphoma typically affects a cat’s lymph nodes, nasal cavity, kidneys, liver, and intestines. If a cat has lymphoma, she may exhibit symptoms including diarrhea, vomiting, and difficulty breathing. Lumps or bumps on the cat’s body may also be evident.

The good thing is feline lymphoma is a treatable cancer. Chemotherapy is typically a very effective treatment option and in many cases, a cat with lymphoma can go into remission and live a very good quality of life. In fact, according to the Animal Cancer Center at Colorado State University, 75% of cats with lymphoma that are treated with chemotherapy will go into remission.

Because the majority of lymphoma cases result from FeLV exposure, vaccinating your cat against feline leukemia can indirectly help protect her from lymphoma.

Squamous Cell Carcinoma in Cats

Squamous cell carcinoma is a type of cancer that usually develops on exposed skin. As a result, on felines, the ears, eyelids, and nose tend to be the most at-risk locations. It can develop in any breed of cat, but white cats and those that reside in very sunny climates are highest at risk.

Squamous cell carcinoma is an aggressive form of cancer, but if it is identified and treated early, then the prognosis is usually good. Because chemotherapy and radiation therapy are rarely effective against this type of cancer, surgical removal of the tumors is usually the most effective treatment option.

Although the majority of squamous cell carcinoma cases are found on a cat’s exposed skin, in some cases, it can develop in the mouth. In fact, oral squamous cell carcinoma accounts for 10% of all cancers found in cats. Unfortunately, while squamous cell carcinoma on the skin usually has a good prognosis, the prognosis for oral squamous cell carcinoma is not as positive.

Signs of oral squamous cell carcinoma include bad breath, difficulty eating, drooling, and weight loss. If the cancer is in the cat’s chin, then you may notice her chin becoming larger and firmer over time.

It is important to note that this is a preventable cancer. You can virtually eliminate your cat’s risk of developing this type of cancer simply by keeping her indoors and avoiding direct exposure to the sun’s ultraviolet rays.


Fibrosarcoma is a type of cancer that develops in a cat’s fibrous connective tissue. Often, the cancerous tumor develops at the site of an injection, which is why it can sometimes be called feline injection-site sarcoma (FISS).

Although fibrosarcoma is one of the three most common types of cancer seen in cats, it is actually quite rare. In fact, the American Veterinary Medical Association estimates that the rate of occurrence is just 1 case for every 10,000 to 30,000 injections. Veterinarians also help keep the risk factor low by limiting the frequency of injections and by specifying where the injections should be administered.

In the event a cat does develop fibrosarcoma, the disease tends to be very aggressive. The treatment plan usually consists of surgical removal of the tumor, with or without chemotherapy or radiation.

Additional Types of Cancers Found in Cats

Although the above three forms of cancer tend to be the most common in cats, they are in no way the only types of cancer that a cat can develop. Cats can also develop cancerous tumors in the lungs, the brain, the liver, and the nasal cavities. Mammary tumors are also a risk, but one that is significantly reduced or even eliminated through spaying.

How to Reduce Your Cat’s Risk of Cancer

Watching a beloved pet waste away from cancer is a terrible and traumatic experience. Thankfully, there are some things you can do to help reduce your cat’s risk of developing cancer.

For starters, you should spay your cat before she enters her first heat cycle. Spaying lowers the cat’s estrogen levels, which if left unchecked plays a major a role in the development of mammary adenocarcinoma.

You should also keep your cat indoors and away from direct sunlight. Another important preventive measure is to take your cat to regularly scheduled veterinarian appointments. Because cats mask their symptoms, it can make it hard for a pet owner to notice their cat is sick, but by taking her to the vet, the veterinarian will conduct a thorough examination that could prove to be life-saving if cancer is detected in its early stages. While at the vet appointment, you should also have your veterinarian tailor your cat’s vaccinations according to her lifestyle and exposure risks.

As difficult as it is identifying cancer in a cat, there are still some signs you should keep an eye out for because when a cat develops cancer, she can exhibit slight behavioral or physical changes, including:

  • Weight loss
  • Sores that won’t heal
  • Loss of appetite
  • Foul odors
  • Difficulty eating or drinking
  • Difficulty breathing
  • Difficulty urinating or defecating
  • Lethargy or lameness
  • Discharge or bleeding from one or more body openings
  • Abnormal swellings or lumps

If you notice one or more of the above signs, take your cat to the veterinarian immediately. In the event your veterinarian decides to prescribe medications for your cat, you can receive a free quote for your cat’s medication from Diamondback Drugs. We can help you save money on your pet medications.

As always, be sure to inform your veterinarian about any medications or supplements your cat is currently taking so your vet can make the best treatment decision for your cat’s unique case and help reduce the risk of a potential drug interaction.

Author: Giano Panzarella