Common Types of Cancers in Senior Cats & Dogs

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Caring for senior pets can be tough. Whether your pets have been with you their whole lives or you adopted them as adults, watching them struggle in old age is heartbreaking. Getting a pet cancer diagnosis is one of the most challenging moments for any pet parent. Fortunately, some cancer cases can be treated or even cured.


It’s crucial to be attentive to your senior pet’s health and well-being. One way to protect them is to understand the health issues they may face, and what those symptoms look like. Below, you’ll learn more about the most common types of cancer in senior pets and the symptoms that indicate cancer.


Common Types of Senior Pet Cancer: Senior Dogs and Senior Cats


Senior Dogs


Senior dogs may experience many health issues over time, including joint problems, cognitive decline, and heart problems. Unfortunately, cancer is a common health issue they encounter. Cancer in senior dogs may cause a sharp drop in overall health and activity levels. There are many types of senior dog cancer, but the following four are the most common.




Lymphoma accounts for 10-20% of all cancer found in dogs. It causes lymph nodes to swell, making them visible on your dog’s neck or under the armpits. Lymphoma can affect any dog breed and any age, although it more commonly affects senior dogs. Dogs are much more likely to get lymphoma than humans.


Canine lymphoma requires diagnostic testing to find the location of the lymphoma. Without treatment, dogs with lymphoma may only live one or two months. With treatment, however, the outlook is much better. About 85% of dogs that undergo treatment will experience cancer remission.




Melanoma is a common variation of skin cancer in canines. This type of skin cancer forms in the skin cells that make pigments in pets’ nails, eyes, and skin. Any breed, unfortunately, can get melanoma, but smaller breeds have a higher risk.


Typically, melanoma occurs in dogs that are ten years or older. Once the vet diagnoses melanoma, local removal is usually an effective treatment. Your vet may remove tissue surrounding the melanoma, as well, to ensure complete removal.


Bone Cancer (Osteosarcoma)


This type of cancer most commonly affects larger breeds, such as Great Danes. Osteosarcoma consists of unrelenting tumors that destroy bone mass. Unfortunately, it’s excruciating for dogs to experience.


Mast Cell Tumors


This is a form of skin cancer that develops near the top layer of the skin. These tumors vary in size, location on the skin, and the amount of inflammation they cause. Mast cell tumors can also affect senior pets in other areas of the body, such as the spleen and intestines.


Senior Cats


Next, you’ll learn about cancer in senior cats. Older cats have a greater risk of cancer than younger cats. Feline leukemia (FeLV) can cause feline cancer. Fortunately, feline leukemia has a vaccination that helps reduce the probability of cancer.


However, some cancers, such as lymphoma, aren’t caused by FeLV, making it the most common cancer in senior cats. Keep reading to learn more about the three most common senior cat cancers: lymphoma, SCC, and breast cancer.




Just like with dogs, lymphoma is the most common cancer in cats. About 30% of feline cancer diagnoses are lymphoma. The most common locations of lymphoma in cats include the intestines, kidneys, and chest organs. Lymphoma can occur in cats of all ages and breeds.


About 65% of cats experience cancer cell remission after undergoing chemotherapy. Diet modifications, including adding supplements like omega-3 fatty acids, may also help treat lymphoma.


Squamous Cell Carcinoma (SCC)


SCC is yet another type of skin cancer, the second most common cancer in cats. SCC primarily affects the skin on the face or inside the mouth. Cancer tumors may bleed and then scab over. Notably, cats with regular exposure to tobacco smoke have twice the risk of SCC.


Your vet will be able to diagnose the illness with a biopsy. Surgery to remove the cancerous skin cells is required, and your vet may also use radiation therapy to prevent further cancer growth. Unfortunately, oral SCC is difficult to treat if it’s located on the back of the tongue or in the throat.


Mammary Gland (Breast) Cancer


This type of cancer affects 17% of female cats. Up to 90 percent of mammary gland growths in cats are malignant. Fortunately, there are a few proven ways to lower the risk of mammary gland cancer in your cat. Spay your kitten before the 6-month mark, and the breast cancer risk reduces by about 91 percent.


In most cases, veterinarians find breast cancer lumps incidentally when the pet parent brings their cat in for a routine check-up. However, pet parents may feel and identify lumps around their cat’s chest area. Typically, surgery and chemotherapy are reliable treatment methods for breast cancer.


Symptoms of Cancer in Senior Pets


In short, cancer is the spread of abnormal cells that destroy normal tissues. In the early stages of pet cancer, there may be little or no noticeable signs or symptoms. Further, pet cancer symptoms vary, so it can be difficult for regular pet parents to diagnose it in their senior pets. Importantly, see a vet if you have any doubts about the symptoms you see or feel.


Symptoms include:


  • Swollen lymph nodes or unusual bumps
  • Abnormal bleeding or unexplained open wounds
  • Wounds that don’t heal
  • Skin inflammation
  • Appetite loss
  • Mobility issues
  • Vomiting and diarrhea

It’s important to be fully aware of your senior pet’s health and activity levels. That way, you can notice symptoms and catch pet cancer in its early stages. When you doubt the symptoms you see, it’s best to visit your vet.


Pet Cancer: Conclusion


So, now that you understand more about pet cancer and its symptoms, use this knowledge to ensure that your senior pets stay healthy and receive early diagnoses if necessary. While no pet parent wants to go through this predicament, helpful treatments exist for many pet cancers. As research and medical technology improve, the well-being and lifespan of our pets will only increase.

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