Can Dogs Get Breast Cancer?

Lumps and bumps on your dog’s belly may have you wondering, “Can dogs get breast cancer?”

Early detection can greatly improve success rates in cancer. By: Oskar Vikman

We often hear breast cancer used when describing a condition that affects humans, but can dogs get breast cancer?

We do not refer to female dogs having breasts; instead we call them mammary glands. Dogs can get mammary gland cancer. The bad aspect of this is that it’s cancer. The good news is the range of treatments and successes veterinarians have had in treating this cancer.

Mammary Gland Tumors

These tumors are common in older dogs. Dogs are living longer with dietary improvements, vaccines, regular veterinary care and being kept inside more, away from dangers such as cars. Living longer can reveal conditions such as mammary gland tumors, and the chances increase greatly for female dogs that are not spayed.

Mammary gland tumors can be benign (does not spread) or malignant (cancerous). Rarely is a combination of both found, but it is possible. Dogs with malignant tumors are at a higher risk of developing a second tumor.

Symptoms of mammary gland tumors most often include lumps or bumps near or under the skin in the area of a mammary gland or lymph node. The lumps can be small, smooth, irregular in shape or change in size rapidly. Some other symptoms include bleeding, ulceration, sudden, rapid enlargement of an existing growth or the appearance of additional growths. Cancer cells can be released and travel to other areas of the body, such as lymph nodes or organs.


Lumps, bumps or any new irregularities on your dog need to be examined by your veterinarian as soon as possible. A physical examination, chest X-rays, biopsy or analysis may be performed to determine if the growth requires treatment. The sooner you seek treatment, the higher the chance of eliminating or slowing the cancer becomes.

My brown lab mix starting having lumps in different areas of her body, not just in the mammary gland area. As soon as they were noticed she was whisked off to the vet’s office. After taking samples from the lumps, the vet was able to tell that they were not tumors but rather the fatty deposits (lipomas) that sometimes plague older Labradors. If the growths had shown to be tumors, treatment would have been started immediately.

Treatment options depend on your dog’s age, overall health, the amount of tumors, the type of tumors and their location(s). Surgical removal is typically recommended unless these other factors are present, but your vet will make a suggestion based on your specific dog’s condition.

Surgical removal can be very successful at removing the tumors and helping to prevent recurrence, and recovery time is usually not very long. A chance may remain for additional growths to form depending on the type of tumor removed. The earlier the tumors are removed the better the prognosis in most cases. Spaying may also be done to lower the risk of recurrence, but the relationship between spaying at an older age and reducing cancer risk is a debatable one.

Additional treatments may include chemotherapy and radiation treatment. Chemotherapy is not as likely a treatment as surgery, although drugs designed to treat this way are constantly changing. Radiation therapy and anti-hormonal drugs are still being researched but may be used. Talk to your vet or vet oncologist about what is currently available and best to treat your dog’s specific condition. In very advanced cases or when the cancer has spread to vital organs, euthanization may be recommended.

Bunny after having her first mastectomy. By: Chris Hughes
Bunny after having her first mastectomy. By: Chris Hughes

A cancer diagnosis is not the death sentence it sounds. If you remember reading the article about one of our animal heroes of the month, Chris Hughes, you might remember he adopted a dog from a shelter because she was left in there with multiple mammary gland tumors down both sides of her body. Bunny was able to have a mastectomy down one side of her mammary glands, and a second operation will be performed to treat the other side.


Prevention is difficult without knowing the exact causes of cancers, but spaying a female dog before the first heat cycle substantially reduces the risk of mammary gland cancer. The risk increases with each heat cycle that passes. Regular vet visits biannually or annually can help keep your dog’s care current and give your vet an opportunity to notice any changes. Feed your dog a quality dog food for optimum health.

Exercise can also play a role in mammary gland cancer. dvm360 states that dogs with a healthy body mass index (BMI) at a young age may have a lower risk of mammary gland cancer, and there is less fat to hide the lumps and bumps that may appear. Although exercise alone should not be considered a way to reduce the risk of mammary gland cancer, it should be a consideration in your dog’s overall health.

Regular examinations are also key for finding growths. Use your hands to feel or massage the belly from the front armpits down to the groin area. You can check this area when your dog is standing up or laying down (at the rate my lab loves belly rubs, this is not a problem). If you find a lump, bump, growth or anything that appears new or different, don’t wait to see if it grows or changes.

Early diagnosis and treatment are key to giving your dog the best chance of kicking the cancer and living a longer life.

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