cancer in cats

Cat Cancer

Diagnosis and Treatment of Cats With Cancer

“Cancer” is a word no pet owner wants to hear, and when we in the veterinary field diagnose a cat patient with cancer, we understand how easy it is to imagine the worst. The truth is, though, there are many different types of cancer, as well as many different types of cancer treatments for cats available. Cancer in cats must be identified and treated quickly for the best chance of successfully defeating feline cancer.

If you suspect that your cat has cancer, contact a local veterinarian for an appointment, exam, and individualized plan. While the information here can help you understand the basics of cat cancer types, signs, and treatments, your veterinarian is your best resource if you have any concerns.

Types of Cancer in Cats

Similarly to humans, cats may have cancers of the skin, mouth, lungs, and more.

Skin Cancers and Tumors

Skin cancer on a cat’s face, ears, or nose can actually be due to exposure to the sunlight. This is especially common in cats that have white hair coats and live in places like Southern California, where they could be outside often and year-round. Just like many of us, cats can enjoy the relaxation that comes with sunbathing - and just like us, this puts them at risk for developing skin cancer.

Other skin tumors and cysts may be difficult to visually distinguish. They may be benign or malignant, and because the causes can be so diverse, professional veterinary evaluation is vital to both identifying the type of skin tumor and the best course of treatment.

These tumors may include:

  • Injection-site sarcoma (tumors that might form where a cat has received an injection)
  • Blood vessel tumors
  • Lipomas
  • Liposarcomas
  • Mast cell tumors

Oral Cavity Tumors

Cats can get cancers in the mouth and throat. The gums, lips, roof of the mouth, and tongue may be the sites of painful, obstructive tumors that can interfere with chewing and swallowing. This is among the most prevalent forms of cancer in cats, such that “oral cavity cancer accounts for about 15 percent to 20 percent of feline malignancies seen each year at the Cornell University Hospital for Animals.


Evidence shows that cats infected with the feline leukemia virus (FeLV) “are 62.1 times more likely to develop lymphoma than are FeLV-negative cats,” though the instance of one illness is not automatically indicative of the other. Unfortunately, lymphoma is the most common cat cancer. This cancer affects certain white blood cells called lymphocytes, which are present throughout the body - including in the kidneys, the lymph nodes, and the intestinal tract. Intestinal lymphoma causes intestinal distress, and this distress can worsen as the cancer worsens, leading to weight loss, vomiting, and other GI signs.

Internal Organ Cancers in Cats

Less often, cats can develop cancers in other internal organs. Tumors in cats can affect the:

  • Lungs
  • Brain
  • Nose and nasal passages
  • Liver

Signs of Cancer in Cats

Skin cancer or a tumor underneath your cat’s skin may be something you can see or feel as you pet or brush them. Otherwise, you should generally look for symptoms that your cat is “just not right.” You know your cat well. You know their normal behavior, and if that changes in any way, then there is likely something that needs to be examined. It is recommended that you bring your cat in to see your veterinarian at a minimum of once a year (though twice a year is best) for a thorough exam. This will often also include lab work to see how your cat is doing in general, which can offer a “wellness baseline”. If lab results differ in the future, that can provide a great clue about your cat’s health as they age.

Diagnosing Cancer in Cats

Diagnosing cancer in a cat depends on the location of the cancer. If it's skin cancer, a bump or a lump, or cancer in the mouth, your veterinary team will likely want to biopsy the lesion or mass. They could simply use a needle to take a small sample, or they may sedate your cat with mild, short-acting anesthesia to take a larger biopsy of the cancer. 

Intestinal cancers can sometimes be diagnosed with ultrasound alone, or ultrasound plus a needle aspirate (using the ultrasound image to guide where a needle is inserted to obtain a sample). In certain instances, a full-thickness biopsy of a piece of tissue - like the intestine, the liver, or the bladder - may be required in order to get a complete diagnosis.

How is Cancer in Cats Treated?

How cat cancer is treated depends on the type of cancer. For instance, skin cancers may be surgically removed. There could also be an opportunity for radiation and/or oncology. Oncology is any kind of medication or chemical formula used to slow the progression, stop the progression, or actually to kill the cancer cells, potentially leading to remission or a cure of the cancer.

Prognosis for Cats with Cancer

Prognosis can vary tremendously with the type of cancer. Often, cats can enjoy a relatively good quality of life with cancer. For example, there are many cats who do very well with intestinal lymphoma thanks to regular oral medication.

However, cats with certain types of cancers have a poor prognosis. Depending on location, there are types of lung tumors that are very severe. Some bladder cancers or throat cancers are difficult to treat as well.

Ultimately, some cancers are very curable, and if they're removed or treated, the cat can live a very full life. Your veterinarian will help you understand your cat’s illness and formulate a personalized plan for your pet.

Preventing Cancer in Cats

Just as with people, cancers in cats are not always predictable. There may be genetic predispositions, environmental factors, or other unforeseen circumstances. The only cancer that you could truly prevent in your cat would be skin cancer, such as squamous cell of the face or ears. You can prevent skin cancer by keeping your cat out of the sun (particularly white cats) and being vigilant about spotting cat cancer symptoms. 

Otherwise, there is no other prevention for cancer for cats. This is another reason that routine veterinary exams are vital for your cat’s health. If your veterinarian can catch any illness, including cancer, early on, there may be a better chance of curing or controlling that illness. 

Follow your veterinarian’s recommended exam schedule for your cat, and contact them right away if you notice anything out of the ordinary between these visits. This will help ensure your cat’s best health, as well as your own peace of mind.

If you think your cat has cancer but haven’t confirmed your suspicions, it’s imperative you reach out to a veterinarian near you to take a proactive approach to treatment.