The thought of cancer strikes fear into the heart of many pet owners. Statistics show that about 20% to 25% of dogs and cats will develop cancer during their lives, and the risk increases as pets age.
The good news is that many pets do well with chemotherapy and other treatments. Even pets with aggressive cancers may experience long remissions (periods during which cancer is not detectable). In some cases, surgery can provide a cure—especially if the cancer is caught early and hasn’t spread.
So when it comes to the big “C”, knowledge is power. As in people, dogs and cats can develop many different types of cancer. Understanding what cancer is, the different types of cancer pets can get, as well as the signs of cancer to watch for in cats and dogs, is important in helping to provide pets with the best quality of life for as long as possible.
What is cancer?
Cancer develops when the DNA in cells become damaged and the resulting abnormal cells begin to multiply uncontrollably. These cells generally form tumours (lumps or growths) that can spread and destroy surrounding tissue. Damaged cells may also be released into the blood and circulate to other areas of the body (metastasize) where they can continue their destruction.
This process can occur in any part of the body, but certain kinds of cancer are more common in pets, including:
- Lymphoma: Affecting the lymphatic system (a transit network that carries and stores immune cells), lymphoma comes in many forms. It can stay localized or can spread throughout the body. Lymphoma can develop in dogs and cats and may be associated with the feline leukaemia virus (FeLV) in cats.
- Hemangiosarcoma: Developing from cells that line the blood vessels, this type of cancer often attacks the spleen but can also affect the heart, liver, and skin.
- Mammary (breast) cancer: These tumours usually begin as tiny nodules near a nipple. Mammary gland carcinomas tend to develop in unspayed female dogs and cats or those spayed after having a heat. Male pets rarely develop this cancer, although it’s possible.
- Mast cell tumours: This kind of cancer tends to form masses or nodules in the skin, but it can also affect other areas, such as the liver, intestine, bone marrow, or spleen.
- Melanoma: A common oral cancer in dogs that tends to affect breeds with dark gums and tongues, melanoma can be difficult to notice in the early stages and unfortunately tends to spread quickly throughout the body. Melanoma is rare in cats but can develop in the skin or the eyes.
- Oral squamous cell carcinoma: The most common oral cancer in cats, squamous cell carcinoma can develop in the gums, tongue, roof of the mouth, or tonsils and can also grow into the jawbone.
- Osteosarcoma: This painful type of bone cancer commonly affects the long bones of the legs. These malignant tumours can also develop in other bones, or even in areas that aren’t bone, such as the kidneys, liver, mammary glands, and spleen.
What are some symptoms I need to watch for in my pet?
The signs of cancer vary depending on the type of cancer, and unfortunately many cancers are silent (don’t have any obvious signs) in the early stages. Many of the signs of cancer are the same as many other diseases such as lameness, abnormal bleeding, coughing, poor appetite, vomiting, diarrhea, weight loss, and trouble breathing. If the cancer involves the skin or tissue just below the skin, you may see a lump or sore that continues to grow, fluctuates in size and may bleed.
What are some risk factors for my pet developing cancer?
Unfortunately, in most cases, there’s not much you can do to try to keep your pet from developing cancer. There are many factors involved in cancer development, including exposure to known carcinogens (cancer-causing agents) such as cigarette smoke, chemicals, and sunlight. Some cancers may be related to obesity, inflammation, and infection, while others can be linked to specific hormones. Certain breeds are also genetically predisposed to developing cancer, and the risk of dogs and cats developing cancer increases with age.
Spaying or neutering your pet can help eliminate or reduce the risk of several types of cancer, including mammary gland, ovarian, testicular, and uterine cancer. Since obesity is believed to play a role in the development of cancer, keep your pet at a healthy weight to help reduce the risk of certain cancers.
We can help pets with cancer!
We have many options to help treat cancer in dogs and cats, including surgery, chemotherapy, and radiation therapy. In southwestern Ontario, we are fortunate to have access to some of the best veterinary oncologists to provide your pet the finest care. Unlike in human medicine, cancer treatment in pets carries less risk of severe side effects. Our goal is to maintain or improve a pet’s quality of life.
Let us know if you see any changes to your pet’s appearance or any signs of illness like those described. The sooner we catch cancer or other medical problems, the better the chance of a positive outcome for your pet.