Types of Feline Cancer and Their Most Common Symptoms

Sadly, one in five cats is diagnosed with cancer at some point during their lives. While cats, like dogs and humans, can suffer from many different kinds of cancer, some are more common than others.

While a cancer diagnosis is emotionally devastating, some are treatable if caught early. This is one reason you want to ensure your cat has regular wellness visits to the veterinarian. Cat cancer symptoms can be subtle, and cats are masters at hiding illness, so a fresh perspective from someone who doesn't see Kitty everyday could make all the difference in spotting something subtle.

Lymphoma, squamous cell carcinoma, mast cell tumour, and fibrosarcoma are among the most common types of feline cancer. Some of the most common symptoms of these cancers are “lumps and bumps.” That is, new lumps, bumps, swellings, or lumps that change size could be signs of cancer. 


Four Common Types of Feline Cancer

Mast cell tumors - Mast cells are a type of normal white blood cell. Occasionally, they can become tumors (MCTs), most of which are cutaneous (skin). They may be benign or malignant, but most (about 90% of cutaneous MCTs) are benign. Visceral MCTs (those that are found in internal organs) are more likely to be aggressive and malignant. Cutaneous MCTs are most commonly first spotted as firm, raised nodules - either confined to one location or widespread. Visceral MCT is harder to spot, but symptoms can include depression, anorexia, weight loss and vomiting. The cause isn’t known, though there seems to be a hereditary component since there are higher incidences in Siamese cats.

Lymphoma - Lymphoma is a type of blood cancer that, typically, develops in the lymph nodes. While lymphoma may cause the peripheral lymph nodes to swell (as it usually does in dogs), more commonly symptoms include weight loss, vomiting, anorexia, diarrhea and lethargy. Experts believe one way cats get lymphoma is through exposure to the Feline Leukemia Virus, and FIV infection can predispose cats to this type of cancer. Lymphoma will have a primary site (where the cancer originated), but it is a systemic disease, so chemotherapy is usually recommended for treatment. While lymphoma is not curable, it can be treated to improve quality of life and lengthen survival time.

Oral squamous cell carcinoma - Squamous cells are those that form your pet’s skin, and tumors from this type of cell are the most common type of oral cancer in cats. The most common way these tumors are found is through bleeding from the tumor. However, other signs, such as increased salivation, trouble eating, facial swelling, and bad breath can indicate a tumor's presence. The preferred treatment for these tumors is surgery; however, because this type of cancer is normally both aggressive and invasive, the tumor's location in the mouth often determines Kitty's prognonsis and quality of life after surgery. Research indicates this type of cancer is associated with flea collar usage and exposure to household tobacco smoke.  

Fibrosarcoma - This type of cancer can include some bone cancers, but is more commonly found in fibrous connective tissues like muscle or other soft tissues. It can be associated with injection sites, so it also can be known as feline injection site sarcoma (FISS). Despite it being one of the more commonly found types of feline cancer, it's still relatively rare (its estimated incidence is 1 case in 10,000-30,000 injections). There are usually very few symptoms associated with this aggressive cancer beyond swelling at the injection site (which can take anywhere from 4 months to 10 years to develop). So if your cat develops an unexplained swelling, be sure to see the veterinarian immediately!


Other Symptoms of Cat Cancer

  • Foul odor 
  • Persistent sores that don't heal
  • Loss of appetite, vomiting and diarrhea
  • Difficulty breathing
  • Unexplained bleeding
  • Lethargy 
  • Failure to thrive


Unfortunately, these symptoms are the same for many different health problems, some more serious than others. Additionally, since cats are experts at masking pain and illness, it may take dramatic signs to alert us to their presence. External symptoms of cat cancer can be hard to spot. Your best chance for catching anything is vigilance, healthy habits, and regular wellness exams for Kitty. We recommend twice a year wellness visits for cats 7 and older.

You can find out more about cat cancer here and you can book an appointment here.


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