Cancer in Cats – Everything You Need To Know

cancer in cats

One of the leading causes of death for cats is cancer. In most cases, cell growth becomes uncontrollable and affects different organs in the cat’s body. Symptoms of cancer on cats are easily detected as it usually manifests through a lump on the body. The affected cell grows rapidly and latches on to the skin closest to it, which results in the lump. It can spread to other parts of the cat’s body, depending on the type of tumor.

Cats over ten years of age have lower chances of surviving cancer. However, if detected earlier, it can be treated successfully.

There are a number of ways to diagnose cancer in cats. A few include blood tests, cytology, ultrasounds, physical examination, urine tests, nuclear scans, and x-rays. Depending on the type of cancer and its severity, there are several treatments widely available which are chemotherapy, surgery, radiation, and immunotherapy.

Sign and Symptoms of Cancer in Cats

Cancer can easily be detected in cats, as these usually show as lumps or bumps. Here is a list of the common signs and symptoms of cancer in cats.

  • Presence of a lump that changes shape or size
  • Bleeding or unexplained discharge
  • A sore that does not heal
  • Difficulty eating or swallowing
  • Trouble urinating
  • Difficulty defecating
  • Change or loss in appetite
  • Change in bladder or bowel habits
  • Drastic weight loss
  • Stiffness
  • Insatiable hunger
  • Change in breath smell

The lumps detected underneath the skin of the cat do not always determine cancerous tumors in cats. There is a high chance that your cat may experience all of the symptoms above without having cancer. We highly encourage that you do not make your diagnosis. If your cat has sudden physical and behavioral changes or has stopped eating or drinking recently, please see your veterinarian as soon as possible.

Cancer in cats

Most Common Types of Cancer in Cats


Lymphoma is cancer in the blood that is the most common type of cancer seen in cats. This happens when lymphocytes, a type of white blood cell, multiply uncontrollably within the cat’s system. Lymphocytes generally fight off infections inside the body. Lymphoma in cats generally affects the following sites:

  • Nasal cavity
  • Lymph nodes
  • Liver
  • Kidneys
  • Intestines

One of the leading causes of lymphoma in cats is the feline leukemia virus (FeLV) before the advancement of the FeLV vaccine. Getting your cat vaccinated with the FeLV vaccine does not only protect it against FeLV, but it will also indirectly protect your cat from certain forms of lymphoma.

Other than it being highly preventable, lymphoma is also one of the easiest types of cancer to treat for your cat. Your cat can go through chemotherapy to kill off any cancer cells in its body. Usually, cats that undergo chemotherapy for lymphoma has a very good prognosis after treatment. According to some studies, about 75% of cats that underwent chemotherapy will go into remission.

Squamous Cell Carcinoma (SCC)

It is also a common type of cancer in cats. Squamous Cell Carcinoma is a type of skin cancer that commonly develops on exposed skin like the nose, ears, and eyelids. White cats that live in sunny areas are more prone to this type of cancer. When SCC happens on the ears, it starts as a black crust, which then progresses along the entire ear. The infected cat’s ear will then shrivel up or have a cauliflower-like appearance.

A solar-induced SCC, if treated early, will have a good prognosis. To prevent this type of cancer, you can have your cats stay indoors when the sun is at its peak, to prevent exposing them to UV rays.

SCC can develop inside your cat’s mouth. Oral SCC accounts for 10% of cancer in cats. Generally, SCC is an aggressive type of cancer, especially oral type. Oral tumors have a very poor prognosis despite having treatment. Unfortunately, this type of cancer is hard to detect as most cats do not like it when anyone opens their mouth. A cat with oral SCC might start to lose weight as feeding can be difficult for them due to the growing tumor in their mouth. If your cat has a sudden change in diet or is not eating properly, consult your veterinarian as soon as possible.

Mammary Gland Tumor

Breast cancer is the third most common type of cancer in cats. It usually affects older female cats and has a higher chance of cats that are not spayed. Spaying a cat should be done at an early age if you want to have the best benefit. The development of this tumor typically relies on the cat getting exposed to hormones. This type of cancer can also occur in male cats that may have been undergoing hormone therapies like progesterone-based drugs for behavioral problems.

What you want to look out for is a lump (tumor) that might develop in one of your cat’s mammary glands. If the tumor has spread out, your cat might feel sick, lethargic, eat less, and lose weight.

Treatment for a mammary gland tumor is usually through surgical removal of the tumor. A breast-sparing surgery is when the affected parts are removed, but some breast tissue is left behind. However, this would still require the cat to undergo follow-up radiation or chemotherapy to kill off any remaining cancer cells.


Fibrosarcoma is another type of aggressive cancer seen in cats. An active tumor starts to develop from the cat’s fibrous connective tissues. A phenomenon called feline injection-site sarcoma (FISS) is when Fibrosarcoma is found to develop in injection sites for various necessary medications and preventives for cats. The following are some injections associated with Fibrosarcoma:

  • Regular vaccines
  • Antibiotics
  • Insulin
  • Subcutaneous fluids
  • Corticosteroids

The good news is that this type of cancer is considered to be rare. According to the American Veterinary Medical Association, only 1 out of 10,000 to 30,000 vaccinations are reported to occur. However, veterinarians will still be cautious in giving vaccines to your feline friends. This includes choosing specific vaccines (those that do not include aluminum, which can increase irritation), limit the frequency of the vaccines given at a time, and choose which site the vaccine will be administered. These factors are taken into consideration, however, there are still multiple factors that could lead to Fibrosarcoma, like medicine doses or genetic factors.

The following cancers, while some may be dangerous, are not very common but should also be taken into consideration depending on the symptoms that your cat is showing:

Ceruminous Adenomas

This type of cancer is usually found at the external ear canal of cats. They are usually dark blue, brown or black.

Myeloproliferative Tumors

This type of cancer is one of the most dangerous types of cancers in cats. It is genetic and has a high possibility of being passed on through reproduction. The most common symptoms for cats that suffer through this type of cancer is difficulty in breathing, loss of appetite, pale mucous membrane, and weakness.

Melanoma Tumors

Melanoma tumor is not very common in cats, but it is important to know what kind of cancer this is since it might still happen. This type of cat cancer is most commonly found on the upper part of a cat’s body, usually the shoulders, neck, head, and ears. Although melanoma tumors are usually benign, it is best to have a regular check-up with your vet to determine your cat’s state of health.

Mast Cell Tumors

Cats that are suspected of having mast cell tumors are encouraged to get biopsied to diagnose this properly. This type of tumor usually appears as skin nodules and are also not very common among cats.

Osteosarcoma Tumors

This type of tumor affects the bones and usually spreads through the joints and the lungs. Symptoms of osteosarcoma usually include swelling, weakness, difficulty in breathing, and constant coughing. This type of tumor is usually detected through x-rays and biopsies.


Depending on the type of cancer, diagnosing the right type can help determine the treatment to be conducted.

Physical Examination

This is the usual and most common test to know whether a cat has cancer. As the affected cancer cell grows, it spreads on the area and sticks to the nearest skin making a lump or bump-like feature. Most cancers are diagnosed through visual observation or manual palpation.


If the cat does not seem to have lumps or bumps, veterinarians may opt for other options such as X-rays. The types of cancers usually detected by this are cancers of the lung, bladder, or gastrointestinal tract.


Sometimes, cats may have cysts that develop into tumors. Ultrasonography helps in visualizing the internal organ structure of the cat. Cats with cysts are encouraged to have regular ultrasonography to monitor if the cysts are benign or if the cysts can progress into tumors.


This method involves an examination wherein the vet takes cells from the affected area, usually where the lump or bump is located. The cells are then tested for the possibility of ruling out cancer wherein the cells may be cysts, abscesses, or granulomas. This is usually a painless procedure.

Nuclear Scanning

Nuclear scanning is commonly known as an MRI for humans. This type of examination helps detect cat cancers in the bones, kidney, spleen, lungs, thyroid, and liver.

Blood Tests

Blood tests are also a common method to diagnose whether a cat has cancer or not. Done through microscopic and biochemical analysis, blood tests help in detecting feline immunodeficiency or feline leukemia. Cats that are suspected of cancer are also often encouraged to get immunofluorescent antibody or IFA to detect FeLV in the blood.


Cats with tumors are usually encouraged to take regular check-ups with the vet to monitor their lumps if they are cancerous or not. If the cat is diagnosed to have cancerous tumors or show any symptoms relating to cancer, they are put into various examinations to know the best treatment plan for their recovery.

Although cancer is the leading cause of death for cats, there are still instances where cats recover from cancer. Here are the treatments that are most commonly used to treat cancers in cats:


When the cat’s cancer has not spread and is easily detected and accessible, surgery can help remove the cancerous tumor from the cat. This is usually done by removing the affected area to prevent it from spreading to other regions of the body. Early diagnosis of cancers in cats is usually given this type of treatment, and the effectivity of recovering from cancer is usually high. Although a regular treatment is still highly encouraged.


This type of treatment destroys the DNA of the cancerous cells and guarantees that the chances of reproduction are stopped. Radiation is usually done either through internal implants or brachytherapy or externally through teletherapy or radioactive beams.


Just like humans, cats that go through chemotherapy may experience weakness, hair loss, nausea, bone marrow depression, and hemorrhaging. Chemotherapy helps break the chromosomes of the cancerous cells and tumors, which make the division of these affected cells impossible. It works with smaller tumors and usually is not effective in large tumors.


This method of treatment works by triggering the immune system of the can to combat the affected cancer cells. The premise of this treatment is that the cancers occur because the cat’s immune system is suppressed by the cancer cells. Immunotherapy asserts that cancer would have been eliminated or prevented in the first place should the microenvironment of the cancers had not been suppressive.


Early detection of cancer in cats help lengthen the life expectancy as long as it is treatable. While this seems to be an ideal way of saving your cat from cancer. Prevention is always a better solution to avoid harm and keep a healthy and happy cat.

It is best to take your cat for regular check-ups to the veterinarian whether your cat seems sick or healthy. This will help you keep track of your cat’s overall health.


Cat vaccines help boost the immune system and fight off harmful viruses and pathogens. Feline leukemia can be avoided with vaccines as well. Consult your veterinarian to have your cats protected with vaccines.


A cat living with a healthy lifestyle is possibly the best type of prevention of any kind of disease. This encourages a boost in the immune system, decreasing the possibility of developing cancer. Give your cats fresh and whole foods, clean and purified water, avoid pollution and decrease the use of harmful chemicals in your household to encourage healthy living for your cat. Doing these can help lengthen the life of your beloved cat.

Interact with Other Cats

Interaction with other feline friends with FeLV-related strains or diseases can be a big risk factor for cats who contract FeLV themselves. Thus a key preventive method is to keep the infected cats in quarantine, apart from the unaffected cats. Stray cats, or indoor/outdoor cats, have been shown to present a higher risk of developing FeLV, as they are more likely to interact with other animals. Domesticated cats kept inside are the least susceptible to disease.

Sun Exposure

Similar to humans, too much exposure to the sun can eventually cause skin cancer. A prolonged period of sun exposure in direct sunlight, especially during the summertime, is very dangerous to cats. White cats are most prone to skin cancer.

A great item to have when your cat particularly enjoys being out in the sun is a sunblock that is specially made for cats. This helps prevent skin irritation, sunburns, and skin cancer. Consult your veterinarian to know the best type of sunblock for your cat.

Spay and Neuter

Male cats can also develop testicular cancer, FeLV ad FIV. Female cats, on the other hand, can develop cancers on their mammary glands, ovaries, and uterus. Spaying and neutering your cat can have a lot of benefits and can decrease the chances of your cat getting cancer.

Limit Exposure to Second Hand Smoking

A cat that lives in a smoker’s household has high risks of developing lymphoma, squamous cell carcinoma, mouth cancer, or and nose cancer. A cat living in a poorly polluted environment also has higher chances of getting cancer through grooming themselves. When cats groom, they usually lick their fur, and a cat may take in the carcinogens that have stuck to it, increasing the risk of cancer.


Cats are very lively creatures and often show very obvious symptoms when they are sick. If your cat is experiencing any of the symptoms shown above, it is best to consult with your veterinarian immediately. Early prevention is always key to keep your cat in its best state of health. Taking your cats to a yearly appointment with the vet whether your cat is healthy or not is also very important to monitor their health as some cats fail to show symptoms despite the presence of cancer.