The cancer rate in dogs and cats is similar to that in people. Cats tend to get cancer a bit less often than people, and dogs tend to get it a bit more often. Generally, as animals age, their chances of developing cancer increase. For instance, cancer is more common in pets that are 10 years old or older. In dogs over 10, nearly half of all deaths are due to cancer. However, even younger animals can get cancer. Age isn't the only factor. In animals, just like in people, genetics, environment, and the presence of other illnesses also contribute to the incidence of cancer.
What Is Cancer?
Cancer cells grow abnormally and uncontrollably, often forming a lump or swelling called a tumor. Any part of the body can develop these abnormal cells, and tumor names are based on where tumors start (for example, kidney tumors are called renal tumors).
The main problem with cancer cells is that they don’t follow the normal rules of cell growth. Healthy cells grow and divide only to replace dead cells or to help young animals grow. Cancer cells, however, keep growing and dividing even when there’s no need for new cells, and they can invade and harm nearby healthy cells.
Tumors can be classified as benign or malignant. Benign tumors form a lump but don’t spread to other parts of the body. They can still cause problems if they grow too large. Malignant tumors are more aggressive. They can invade nearby tissues and spread to other areas (a process called metastasis), making them harder to treat. The term "cancer" usually refers to malignant tumors.
Does Cancer Spread in an Animal?
Once a cell becomes cancerous, it starts to grow and spread. Because these cells grow uncontrollably, cancer can spread (metastasize) through the body’s lymph nodes or bloodstream.
What Types of Cancer Can Animals Get?
Like cancers in people, some types of cancer in pets are more common than other types of cancer. The most frequently seen cancers in pets include breast cancer, skin cancer, bone cancer, mouth cancer, and cancers of the lymphatic system.
Blood cancers are called leukemias, and cancers affecting blood-forming tissues (like bone marrow) are known as lymphomas. A cancer that develops from the cells that cover body surfaces and make up glands is called a carcinoma. Common carcinomas include those of the skin, lungs, colon, stomach, breast, prostate, and thyroid. Younger animals usually get carcinomas less often than older pets do, but these cancers can occur at any age.
When muscle or connective tissue (like cartilage, bone, or fat) becomes cancerous, the tumor is called a sarcoma. Osteosarcoma is a well-known type of bone cancer.
