Dog Tips

5 Common Cancers in Dogs

It’s a word that we never want to hear or even think about.


Unfortunately, dogs are at risk of getting many of the same cancers that humans get. The National Cancer Institute estimates that around 6 million dogs are diagnosed with cancer each year. (1)

Around 25% of dogs will get cancer during their lifetime, which makes it a very real and scary thing that we as pet parents need to consider. (2)

What is Cancer in Dogs?

Let’s start by breaking down what cancer is. Cancer occurs when a large number of uncontrolled cells grow and collect in one area of the body. These cells will often result in abnormal tissue masses, otherwise known as tumors. Some forms of cancer do not result in tumors, but the majority will result in one or more tumors if left untreated. Typically, the cancer cells will continue to grow quickly and spread to other parts of the body.

While we’re unsure what the exact cause of cancer is currently, the primary theory is that cancer forms as a result of genetic damage in the cancer cells. In other cases, exposure to a carcinogen, such as cigarette smoke, sunlight, or chemicals, may be to blame. Different dog breeds are also more prone to certain types of cancer-based on their personal genetic makeup, size, and build.

Regardless of why cancer happens, it’s currently the leading cause of death in older dogs.


Lymphoma is a very common cancer in dogs, resulting in around 24% of all new cancer diagnoses in dogs currently.

Lymphoma is a cancer of the lymphoid tissues and lymphocytes, which are a type of white blood cell. Lymphoid tissues are in many parts of the body, including the spleen, digestive tract, liver, bone marrow, and lymph nodes. When lymphoma occurs, it can result in a noticeably enlarged lymph node under the neck, in front of the shoulders, or behind the knees. Other organs where lymphoid tissues live are often affected.

Chemotherapy has been shown to be particularly effective against lymphoma and most dogs treated will go into remission.

Oral Melanoma

Melanoma is a common oral cancer that occurs frequently in dogs with darker gums and tongues, such as Scottish Terriers or Doberman Pinschers. You may also be interested in Miniature Pinscher. Unfortunately, melanoma often forms in oral cavities, which makes surgical removal impossible in many cases.

Chemotherapy and radiation have been shown to be largely ineffective against this form of cancer, but immune-based therapies and other treatments in development are proving to be better at fighting against melanoma. (5)

Brain Tumors

The first warning sign many pet parents get that their pup is suffering from a brain tumor is usually an epileptic like seizure or huge change in personality and behavior. CAT scans are typically performed by a veterinarian to identify the tumor.

Currently, surgery to remove the tumor is one of the best ways to handle this form of tumor. Radiation may be used on inoperable brain tumors.

Liver Cancer

Hepatocellular carcinoma (HCC) is the most common form of liver cancer in dogs, though many types of cancer will find their way to the liver. Older dogs are most at risk of developing liver cancer, though young dogs are still at risk. Currently, liver cancer seems to affect all dog breeds equally.

The main treatment for liver cancer is a partial removal of the liver. A veterinarian will surgically remove the affected part of the liver and leave the rest of the organ in peace so that it can work to regenerate itself. Amazingly, the liver can regenerate even when a massive portion of the liver is removed! (7)

Mammary Tumors

Mammary tumors are some of the most aggressive and difficult to treat cancers, however, they are preventable in many cases. Female dogs who are not spayed have a much higher chance of developing a mammary tumor.

It’s estimated that not spayed female dogs have a seven-fold increased chance of getting a mammary tumor when compared to neutered female dogs. Obesity is another contributing factor. Dogs who are obese and unspayed at one year old are three times more likely to develop a mammary tumor during their lifetime. Know more about the costs of spaying and neutering a dog.

There are many benefits of a healthy lifestyle and neutering your pup. For more information on the benefits of spaying and neutering your pup.

The Importance of Prevention and Preparation

You may be asking yourself how you can prevent or help your dog should they get cancer?

The best thing you can do for your dog is to work on preventive measures. Taking your dog to regular veterinary appointments, giving them plenty of time to exercise daily, and keeping them at a healthy weight are all key ways that you can help your pup to be healthier. Regular veterinary appointments allow your veterinarian to run routine tests to scan for common health problems, including cancer so that your dog can be treated as soon as possible should they have anything.

Prevention can do wonders for your dog, but what can you do if the worst still happens?

This is where pet insurance comes into play. Insuring your pet now helps you get reimbursed later in their life if they develop cancer or other chronic conditions. In fact, dog insurance can help cover the costs of cancer treatment.

Don’t wait on this – dogs can develop cancer at any age and the sooner you have your pup covered, the sooner you’ll feel peace of mind that you’ll have support caring for them!


  • National Cancer Institute,

  • American Veterinary Medical Association,

  • Veterinary Centers of America,

  • Flint Animal Cancer Center,

  • American Animal Hospital Association,

  • Canine Cancer,

  • American Kennel Club,

  • American Kennel Club

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