7 Types of Cancer in Dogs

Kate Barrington
by Kate Barrington
There’s more than one type of cancer that can affect your dog. Let’s talk about the seven most common types of cancer that a dog can suffer from.

The “c-word” is enough to strike fear into the heart of any dog owner and, unfortunately, cancer is very common in dogs. In fact, it is the leading cause of natural death, affecting more than 50% of dogs over the age of 10. Cancer comes in many different forms – keep reading to learn about seven of the most common types of cancer seen in dogs.


A type of blood-borne cancer, lymphoma affects the white blood cells known as lymphocytes. There are several forms of lymphoma but the most common manifests with swollen lymph nodes. This form of cancer is highly treatable with chemotherapy which typically offers a prognosis of 1 to 2 years.

Related: What You Need To Know About Lymphoma In Dogs


An adenocarcinoma is a malignant tumor that forms in the glandular and epithelial tissue. It can develop on many parts of the body but is most common in the gastrointestinal system, especially in older dogs. Adenocarcinoma can cause symptoms such as vomiting, weight loss, abdominal pain, or poor appetite and while the exact cause is unknown, there may be a genetic link in certain breeds.


A type of slow-growing tumor, fibrosarcoma is typically found in the connective tissues and just below the skin’s surface. The cause of this form of cancer is unknown but it is most common in large-breed dogs and middle-aged dogs and older. Surgery is the most common treatment option for fibrosarcoma, though radiation is another option.

Related: What is Hemangiosarcoma in Dogs?


This is a cancer of the blood vessels and it most commonly develops in the spleen. A hemangiosarcoma can rupture and, when it does, it may cause pale gums, labored breathing, and trouble rising. It is also possible for this cancer to form in the dog’s heart or skin and a tissue sample analysis is required for diagnosis. The most common treatment is surgery to remove the affected area followed by chemotherapy to reduce the risk for metastasis.


A common form of skin cancer, melanoma affects the pigmented skin cells and typically forms dark brown or black tumors. In many cases, masses that form on the skin are benign but when they form in the mouth or nailbed they can be malignant and very aggressive. Melanoma also comes with a high risk for metastasis, particularly to the lymph nodes, lungs, and liver. A combination of surgery, radiation, and immunotherapy is often warranted.


Most commonly seen in large and giant breeds like Great Danes and Greyhounds, osteosarcoma is a type of bone cancer. Easily confused for arthritis, osteosarcoma can be diagnosed via x-ray and the treatment of choice is usually amputation of the affected limb followed by chemotherapy. In milder cases, a limb-sparing procedure might be an option but it is an expensive procedure with a very lengthy recovery time.

Mast Cell Tumors

Perhaps the most common type of skin cancer in dogs, mast cell tumors manifest as red, itchy lumps that grow very quickly. These lumps contain a chemical called histamine and, in addition to causing itching, it signals the stomach to increase acid production – for this reason, dogs with mast cell tumors have a high risk for gastrointestinal ulcers. After diagnosis, treatment usually involves surgical removal of the tumors.

Though you shouldn’t automatically assume the worst, it is important to acknowledge behavioral changes and physical symptoms if your dog starts to develop them. The sooner you diagnose cancer, the sooner your dog can receive treatment and the more likely he is to recover.

Kate Barrington
Kate Barrington

Kate Barrington is the loving owner of two cats (Bagel and Munchkin) and a noisy herd of guinea pigs. Having grown up with golden retrievers, Kate has a great deal of experience with dogs but labels herself a lover of all pets. Having received a Bachelor's degree in English, Kate has combined her love for pets and her passion for writing to create her own freelance writing business, specializing in the pet niche.

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