The Warning Signs of Cancer in Cats

Not too long ago, when a cat owner learned that a pet had cancer, it meant a death sentence for the animal. But, thanks to advances in feline cancer research, things have changed.

Cancer is an uncontrolled growth of cells on or within the body. It may be localized, or it may invade adjacent tissue and spread throughout the body. Cancer is common in pet animals, and the rate increases with age. Dogs get cancer at roughly the same rate as humans, while cats get fewer cancers. Cancer accounts for almost half of the deaths of pets over 10 years of age.

Unfortunately, the cause of most cancers is not known and therefore prevention is difficult. One known cause of cancer is an injection, most often a vaccination, which may spur an overzealous inflammatory or immune system reaction to the vaccine. This is called an injection-site sarcoma. Other cancer, such as breast cancer, is largely preventable with early spaying. Fifty percent of all breast tumors in dogs and 85 percent of all breast tumors in cats are malignant. Spaying your pet prior to the first heat cycle will greatly reduce the risk of breast cancer.

Cancer can occur in almost any location or body system – for example areas such as the skin, gastrointestinal tract (stomach, bowels), urinary system (kidney or bladder), blood, nervous system (brain tumors), and bones.

Different types of tumors can grow in each location of the cancer. A cellular diagnosis is needed to determine the “type” of cancer. For example, cancer of the skin can be due to basal cell tumors, squamous cell carcinoma, mast cell tumors, lymphosarcoma and fibrosarcoma. Each tumor type within a location has a different treatment and prognosis.

Signs of Feline Cancer

Do you know the signs of cancer in cats? Cats get many of the same types of cancer as humans, and frequent physical exams and diagnostic tests help detect cancer before it is too late for treatment. Some common types of cancer in cats are:

Skin tumors. Although they are very common in older dogs, they are much less common in cats. However, most skin tumors in cats are malignant. All skin tumors – lumps or masses of any sort – should be examined by your veterinarian.

Lymphoma. This form of cancer is common in dogs and cats, and in cats it may be associated with feline leukemia virus (25 percent of all cases). The most common form of lymphoma in the cat affects the digestive system. The most common signs are lethargy, vomiting and diarrhea.

Mammary gland tumors. These tumors are more common in the older female cat. It is the third most common type of cancer in cats, behind skin tumors and lymphoma. Over 85 percent of these tumors in cats are malignant. Typically, a lump is felt in the breast tissue. Although they are most common in intact cats, they can also occur in spayed cats.

Abdominal tumors. Abdominal tumors are common, but it is difficult to make an early diagnosis. You should be aware of any weight loss, protracted vomiting, continual diarrhea, and/or abdominal enlargement and see your veterinarian if these signs occur.

What to Watch For

Signs of cancer in cats may include: 

Any lump or mass that appears to be increasing in size

Any sore that does not heal

Change in bowel or bladder habits

Difficulty urinating or defecating

Unexplained bleeding or discharge from any body opening

Loss of appetite

Weight loss

Difficulty breathing

Persistent lameness or stiffness

Offensive odor

Difficulty eating or swallowing

If you notice any of the symptoms, consult with your veterinarian. If found early, most of these cancers can be cured with surgery, chemotherapy, radiation therapy, or a combination of the three, and early diagnosis will aid your veterinarian in delivering the best care possible.​​