Cats & Cancer: What You Need to Know

November is Pet Cancer Awareness Month! It's estimated that one in five cats will be diagnosed with cancer. So while it's wonderful that our cats are living longer lives, it means an increased risk that cancer could strike. Thankfully, progress in how we understand and treat cancer means there are more treatment options available that can help ensure our feline friends are kept healthy and happy for as long as possible.

The cause of a cat's cancer is often unknown. Some cancer types may have a genetic element and be inherited, and environmental factors and carcinogens can also play a role. We do know that the feline leukemia virus (FeLV) can cause lymphoma and leukemia in cats, and that feline immunodeficiency virus (FIV) is a risk factor for developing cancer. Your vet can test for both of these viruses, and keeping your cat indoors can help protect her from contracting them!

White cats have an increased risk of developing squamous cell carcinoma, particularly on their face and ears. In very rare cases, vaccination can lead to the formation of a fibrosarcoma—but it's a small chance. The Veterinary Information Network reports that studies have found only 1 in 1,000 to 1 in 10,000 vaccines will lead to formation of a fibrosarcoma—much less than the risk of contracting one of the diseases that vaccines protect against.

Most Common Types of Cancer in Cats
There are many types of cancer in cats. Each type is named for the cells from which the tumor originated. For example, lymphoma affects the lymphatic system, while osteosarcoma affects bone. For every type of cell in the body, from your cat's skin to her stomach and blood vessels, there is a corresponding type of cancer. The cells most likely to become cancerous are ones that rapidly divide.

The most common sites for cancer in cats include:

  • Skin
  • White blood cells
  • Mouth
  • Gastrointestinal tract (stomach and intestines)
  • Mammary glands

Lymphoma is the most common cancer in cats. This is cancer of the lymphocytes (a type of white blood cell) and lymph node tissues. Enlarged lymph nodes are a hallmark of this cancer type, as well as weight loss, vomiting, and diarrhea. FeLV and FIV-positive cats are at increased risk.

Oral squamous cell carcinoma is the most common oral cancer in cats, and affects the cells that line the skin and mouth. This cancer can be very difficult to treat.

Signs and Symptoms of Cancer in Cats:

  • Bad breath or odor
  • Behavior changes
  • Diarrhea
  • Difficulty breathing
  • Drooling
  • Enlarged lymph nodes
  • Hiding
  • Icterus (yellow appearance to skin)
  • Lameness
  • Lethargy
  • Lumps
  • Pain and discomfort
  • Pale gums
  • Poor appetite
  • Snorting
  • Sores that don't heal
  • Swelling
  • Vomiting
  • Weight loss

Many of these signs could apply to a number of conditions, but age can be a risk factor. Senior cats are more likely to have cancer than younger cats. Any time your cat seems off, especially if it persists for several days or more, she should be examined by a veterinarian to determine what is going on.