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Happy Healthy Pets™

Cancer in Pets

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Cancer is unfortunately a common diagnosis for pets. However, veterinary advances in early detection, diagnosis, and treatment mean your pet’s cancer has a much higher likelihood of being treated successfully when diagnosed in the earliest stages.  

Cancer develops when abnormal, old, or damaged cells survive and replicate, often resulting in an abnormal tissue mass ( i.e., tumor). Early detection greatly increases a pet’s prognosis, allowing for easier surgery and potentially prevention of spread.  

While not all cancers can be cured, your veterinary care professional can successfully manage the disease, giving you more quality time with your precious pet. Many pets develop cancer during their lifetime, and learning about the most common cancer types, signs, and treatments can empower you to care for your pet, if your veterinarian diagnoses them with the disease.  

Common canine cancers 

Nearly 50% of senior dogs develop some form of cancer, which is the leading cause of death in dogs older than age 10. While cancer is more common in older pets, this disease can affect younger dogs as well. Common canine cancers include: 

  • Lymphoma — Lymphoma is a cancer of lymphocytes—a type of white blood cell that plays a part in immunity. Lymphocytes make up the lymphoid tissue throughout the body, meaning lymphoma can develop in any body area, such as the lymph nodes, gastrointestinal tract, liver, kidneys, or spleen. Because lymphoma takes many different forms—with unique signs—accurately diagnosing the specific type is critical to effective treatment.  

  • Hemangiosarcoma — Hemangiosarcoma is a fast-moving, malignant cancer arising from cells that normally create blood vessels. While this disease can form tumors in almost any body area, hemangiosarcomas most commonly affects the spleen, liver, heart, and skin. Any dog breed can develop hemangiosarcoma, but some breeds—golden and Labrador retrievers, and German shepherd dogs—have a higher risk. Because hemangiosarcoma is often diagnosed in the advanced stages, dogs commonly require emergency surgical tumor removal to prevent rupture and subsequent bleeding, or humane euthanasia. 

  • Mast cell tumors — Mast cell tumors commonly occur in or immediately underneath the skin, but can also develop in internal organs. Mast cells are responsible for histamine release often causing red, hairless masses that wax and wane. They can cause hives, swelling and bruising around the local tumor.  Mast cell tumors exhibit a variety of biological behaviors ranging from small locally aggressive masses, to tumors that spread easily.  This cancer can often be cured if it is detected early.  

  • Melanoma — Unlike in people, melanomas of the skin in dogs are often benign. However, our canine companions can develop melanomas under the toenails or within the mouth that are locally aggressive and can spread to other places in the body. Recently noticed poor breath, concerns with eating, and bleeding toe nails that don’t resolve with antibiotics are causes to see your local veterinarian. The earlier this disease is caught the more treatable it is.  

  • Osteosarcoma — This painful bone cancer affects a dog’s long bones, such as the leg bones. Although any breed can develop osteosarcoma, large and giant breeds are especially susceptible. If left untreated, osteosarcoma can spread to the lungs and other organs. This aggressive cancer often requires the affected leg’s amputation, followed by chemotherapy. 

Common feline cancers 

Cats commonly live to 20 years of age or older, and—similar to dogs—are likely to develop cancer later in life. However, cats of any age are susceptible to cancer, especially the following disease types: 

  • Lymphoma — Lymphoma is by far the most common cancer affecting cats, and those who have the feline leukemia virus (FeLV) have a much higher lymphoma risk. While lymphoma is a highly aggressive cancer, multiple treatment options—most often chemotherapy—are available.    

  • Squamous cell carcinoma — This cancer has a low risk of spreading, but the tumors can be locally invasive and aggressive, and can cause destruction to local tissues. This is most commonly noted in the mouth, where the tumors cause pain and bone destruction. It can also occur on the non-pigmented areas of the pinna, nose, and eyelids of white cats who like to sunbathe. Treatment such as surgery or electrochemotherapy can sometimes be used to cure this type of cancer. Oral squamous cell carcinomas are often challenging to treat and often yield a poor prognosis since surgery is difficult and the tumor is often found at a late stage.  

  • Mammary carcinoma — Mammary tumors usually develop in older female cats, and are 85% malignant. Spaying your cat before her first heat cycle significantly reduces her late-in-life mammary cancer risk. Surgery is recommended, sometimes followed by chemotherapy. 

Common cancer signs in pets  

When your pet’s cancer is diagnosed at an early stage, the disease is often more responsive to treatment, and surgery may be easier. While cancer in pets is not easily detected, you can be instrumental in your pet’s early cancer diagnosis when you keep an eye out for the following changes:  

  • Decreased appetite 

  • Weight loss 

  • Abnormal masses that suddenly appear or continue to grow 

  • Sores that do not heal 

  • Abnormal discharge or odor from any orifice 

  • Difficulty eating or swallowing 

  • Limping, stiffness, or reluctance to move 

With early diagnosis and treatment, many pets’ cancer can be successfully treated, and regular wellness exams and preventive care are key to protecting your pet from this disease. Use this locator to find a veterinary hospital near you, and schedule your pet’s wellness exam today. 

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