Cancer in Pets: What You Need to Know


Despite incredible advancements in veterinary medicine, veterinary professionals see more cancer in pets than ever before, which might be due in part to our furry companions’ longer lives. Overall, the American Veterinary Medical Association (AVMA) estimates about one in four dogs will develop neoplasia at some point in their lives, and almost half over the age of ten will develop cancer.


Some of the most common types of cancer in pets include:

● Osteosarcoma — Osteosarcoma is a highly aggressive bone cancer that most commonly invades the limb bones in large- and giant-breed dogs. All too often, metastases to the lungs have formed by the time this cancer is diagnosed, making the prognosis a grim one.

● Mammary gland cancer — Highly preventable through correctly timed spaying of female pets. Mammary gland cancer is the most common tumour found in female dogs. Mammary tumours in cats are malignant 85% of the time; in dogs, they are cancerous about half the time.

● Hemangiosarcoma — This aggressive cancer affects vascular endothelial cells, with tumours most often occurring in the spleen or heart. Certain breeds are more predisposed than others, including boxers, German shepherds, Labradors, and golden retrievers.

● Lymphoma — Lymphoma is a cancer of the lymph system, which is part of the immune system. In cats, one in three cancer diagnoses is lymphoma, with the gastrointestinal tract most commonly affected.

● Mast cell tumours — More common in dogs than cats, these skin tumours can range from relatively benign if removed early to seriously malignant and aggressive.


Certain signs seem to point to cancer development in pets, so keep a sharp eye out for the following potential cancer indicators:

● Growing lumps, bumps, or swellings that do not go away

● Sores that do not heal

● Weight loss

● Decreased appetite

● Abnormal bleeding or discharge

● Unpleasant odour

● Difficulty swallowing or eating

● Lethargy

● Persistent lameness

● Difficulty breathing

● Problems urinating or defecating

● Vomiting or diarrhea


Although many of these signs can be caused by other diseases, they all require veterinary attention to help your pet feel their best again. If you notice any abnormalities in your pet, contact your veterinarian right away.