Cat Cancer Explained

Like cancer in any animal, cat cancer occurs when a piece of tissue in the animal undergoes a series of mutations that cause it to grow continuously. This forms a lump of mutated tissue called a tumor. Organisms die of cancer because the tumor can do serious structural damage within the body, as well as drain the organism's energy and nutrients. When cancer tissue becomes malignant, individual cells can fall off the tumor and become lodged elsewhere in the body, leading to more tumors.

A cat is much more likely to survive if the cancer is detected and treated before it becomes malignant. It is normal for cancer cells to form in cats, but the immune system can usually kill them before they cause a problem, so cancer can only occur if the immune system is compromised.


Cancer becomes much more dangerous as the disease develops, so it is extremely important to detect and treat it as early as possible. The most obvious sign that your cat has cancer is a lump that seems to be increasing in size or changing in shape. The tumor may be deeper within the cat's body, so it may not be visible.

Since cancerous tissue drains the body of nutrients it uses to create new tissue, cats with cancer either do not regenerate tissue or do it very slowly. If your cat bleeds unexpectedly or has sores that do not heal, it could be a sign of cancer.

Cancer can also affect the cat's eating habits, so a sudden loss of appetite or a difficulty eating or swallowing food could be reason to suspect that your cat has cancer.

Other common symptoms of feline cancer are persisting stiffness in joints, problems breathing, or bad odors.


The three most common treatment options for felines with cancer are surgery, chemotherapy and radiation therapy. Surgery is most often effective before a tumor becomes malignant. It cannot be used if the tumor is on a major organ, or if the cancer is of a variety that involves the bloodstream, such as leukemia. Surgical treatment of cancer involves simply cutting the mutated tissue out of the body.

Chemotherapy is most often used when the cancer is already malignant. Chemotherapy involves the use of toxic chemicals to kill cancer cells. These chemicals are pumped through the whole body, and kill many healthy cells, but are most effective at killing cancer cells, so it is considered to do more good than harm.

Radiation therapy is used when a tumor cannot be removed surgically because of its location in the body. It is also used before surgery or chemotherapy to reduce the size of a tumor, or after surgery or chemo to eliminate any remaining cancer cells. Radiation treatment uses high energy X-ray radiation to kill cancer tissue, so one side effect of this kind of treatment is that many healthy cells are also killed.

Cancer in cats is not as common as it is in humans, but it is often just as deadly. The most important thing to remember about cancer is that it should be detected early. The earlier cancer is discovered, the higher the chance of survival.