Understanding Cancer in Cats

According to the Smithsonian, humans have had domesticated pet cats for over 12,000 years. In that time, humans and cats have developed a strong relationship. They continue to quell anxieties, provide comfort, and catch pests, and we care for them, show them love, and make sure that they live healthy lives.

A cat will, on average, live for about 15 years, but even cats can succumb to diseases, including various forms of cancer. While cancer is more common in dogs, it can still be a prevalent disease in your favorite feline friends.

Cancer affects an estimated 6 million cats each year, and it is the leading cause of deaths in about 32 percent of cats. Let’s take a closer look at cat cancer in its different forms, its symptoms, and what you can do to treat or prevent cancer in your cats.

cat cancer

Possible Causes of Feline Cancer

Much like cancer in humans, feline cancer is hard to pin down. There isn’t any single known reason for a cat developing cancer. Many are caused by a mix of genetics and environmental factors that took effect years before the cat’s actual diagnosis.

Genetic mutations can be passed down, increasing a cat’s predisposition to growing certain tumors, but most mutations happen during a cat’s lifetime. Internal factors causing these mutations include exposure to certain hormones, while external factors include everything from tobacco smoke to sunlight.

However, there are some known factors that may contribute to an increased risk of cancer in cats. For example, cats that have been spayed after the age of six months are about seven times more likely to develop mammary tumors (which can point to mammary gland cancer) than cats spayed before six months. Studies also suggest an association between feline immunodeficiency virus and feline leukemia and lymphoma.

causes of cat cancer

Cat Cancer Symptoms

Cats who may have cancer can exhibit a wide range of signs and symptoms, both physical and behavioral. Some common signs of cat cancer you should keep an eye out for include:

  • Weight loss: Sudden or gradual loss of weight is the most common sign of possible cancer, often suggesting a gastrointestinal tumor. Cats are heavily motivated by food, so a sudden loss of appetite could point to problems.
  • Weight gain: At the other end of the spectrum, your cat should maintain a pretty consistent weight. A sudden increased appetite, bloating, or general weight gain could point to gastrointestinal cancer. This can be especially serious if your cat gains weight while seemingly eating less.
  • Hiding: Cats are natural hiders, but if they are spending more time than usual hiding under the bed, bundled under your covers, or in otherwise hard to reach places, you may want to seek help from a vet. This doesn’t necessarily point to cancer specifically, but it is a big indicator that something may be wrong with your cat’s health.
  • Nosebleeds: While nosebleeds may be fairly normal for humans, they’re nowhere near normal for cats. In younger cats, a bloody nose might mean your cat got a foreign object stuck in its nose. However, in older cats, nosebleeds can be a major sign of nose cancer.
  • Oral issues: These include sores, bleeding, lumps, discolored gums, and consistent bad breath. These can all suggest oral cancer. The worst part: most owners don’t inspect their cats’ mouths enough, which means these symptoms often go unnoticed until too late. Keep an eye on your cat’s mouth when she yawns or eats, and get into the habit of brushing your cat’s teeth regularly.
  • Discharge: Discharge from the nose can point to nasal cancer, while irregular discharge from the eyes may mean an eye tumor.
  • Irregular bathroom habits: Diarrhea itself isn’t a sign of cancer, but you should take your cat to the vet regardless if it exhibits persistent diarrhea. Other digestive issues you should keep an eye out for include difficulty urinating or moving bowels, blood in stools or urine, or sudden increased use of litter box. While this could just mean an upset stomach, it could also signal tumors in the gastrointestinal tract.
  • Skin problems: Watch for lesions or sores that don’t heal or appear itchy.
  • Seizures: It goes without saying that you should see a vet if your cat experiences seizures of any kind. Seizures may appear as sudden bursts of activity, jerking legs, chewing, and foaming at the mouth. Atypical seizures may appear more as abnormal behavior, like scratching or biting you, sudden anger, or excessive licking.
  • General pain: Aches and pains are a common part of growing old as a cat, but if your normally affectionate feline companion suddenly whines or cries out when you pet them or pick them up, you should consider taking them to the vet.

While tumors are commonly associated with cancer, they could very well be benign. There’s no way to know without a professional test and diagnosis.

symptoms of cat cancer

The Most Common Types of Feline Cancer

Much like human cancer, feline cancer comes in various forms affecting different organs and organ systems. Some may be more aggressive than others. Some of the most common types of feline cancer include:

  • Feline lymphoma, or lymphosarcoma, affects a cat’s lymphocytes, a cell involved in the cat’s immune system. This can lead to potential widespread infection, so lymphoma is itself divided into forms that differ in age of diagnosis, symptoms, and treatment. Forms of cat lymphoma include:
    • Gastrointestinal
    • Renal
    • Nasal
    • Spinal (both the brain and spinal cord)
    • Mediastinal (lymph nodes located in the chest)
    • Multicentric (involving several different organs)
  • Fibrosarcoma develops as an aggressive tumor in fibrous connective tissues, often where your cats might have received an injection of antibiotics, vaccines, and other medications and preventatives. This form of feline cancer is rare, only occurring in about 1 out of every 30,000 vaccinations. To reduce the potential for fibrosarcoma, vets will often limit the frequency of vaccinations and suggest specific vaccines that have lowered chance of infection or irritation. When caught early, fibrosarcomas only have up to a 20 percent chance of metastasizing.
  • Squamous cell carcinoma is a type of cat skin cancer that cats may develop on their noses, ears, eyelids, and other areas of exposed skin. White cats in sunny climates may especially be at risk for squamous cell carcinomas, which account for about 15 percent of all skin tumors in cats. Cats who frequently receive sun exposure may first develop solar dermatitis, which can appear as pink, scaly skin, for which your vet will prescribe sun restriction and sunscreen. However, exacerbated solar dermatitis can turn into open wounds or growths that look like cauliflower. At this point, the vet may test to see if the cells have become cancerous.
  • Mammary gland carcinomas usually occur in older cats ages 10 to 14 years. Sadly, mammary tumors are more aggressive in cats than in other species. About 80 to 90 percent of mammary gland tumors are found to be malignant. They are usually locally invasive, spreading to immediately adjacent areas with a high chance of metastasizing.

types of cat cancer

types of cat cancer

A Look at Feline Leukemia Virus

When humans hear leukemia, they assume it’s much like the human equivalent of cancer of the blood cells. In reality, feline leukemia virus (FeLV) is not cancer but a viral disease more comparable to human HIV. While related, FeLV is not the same as feline immunodeficiency virus.

Feline leukemia suppresses a cat’s immune system, making it more susceptible to infections and illnesses. When left unchecked, FeLV can lead to blood disorders and cancer. Signs of FeLV include:

  • Loss of appetite
  • Fever
  • Diarrhea
  • Inflammation of the gums and mouth
  • Swollen lymph nodes

FeLV is most often spread by cats who are already infected with the disease. The virus has a high concentration in saliva, urine, feces, and milk of infected cats. The disease can be spread via bite wounds, mutual grooming, and shari