BaxterBoo Blog
October 8, 2019

Not So Fun Fact: Dogs Can Get Breast Cancer Too

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With it being Breast Cancer Awareness Month, everyone should be aware that dogs too can get breast cancer. Though none of us want to even think about there being something that could hurt our furry best friends, it is better to find out sooner so you can get them to help ASAP. This disease can be successfully treated if caught early on but it is very common in dogs. Here is some background on breast cancer as well as some signs to look out for and possible treatment options.



This horrible disease in dogs is also referred to as mammary tumors. Dogs often develop breast cancer because they were not spayed before their first or second heat period. Unspayed dogs are 7 times more likely to get mammary than those who have been spayed. Sex hormones produced by canine ovaries during their six-month cycle cause a harmful sensitization or pre-programming of the breast tissue. This hormonal influence ultimately causes point mutations in the genes of the breast tissue cells that dictate tumor growth. An intact female dog may develop a tumor in any one of her ten mammary glands and over half will present with more than one tumor. This disease usually strikes approximately one in four unspayed female dogs over the age of two. Half of the mammary tumors found in canines are benign, and of the half that is malignant, most can be successfully treated with surgery if caught early enough. Although it is rare, male dogs may also develop breast cancers. Breast cancer in males tends to metastasize aggressively.


What is a Mammary Gland?

The mammary gland is the milk-producing gland of women and other female mammals.


Signs To Be On The Lookout For

Most of the signs of breast cancer are related to the tumors themselves and are located on one of the eight to ten mammary glands present on most female dogs. The majority of tumors are found near the mammary glands closest to the back legs. Be on the lookout for:

  • Bloody discharge or pus from the nipple

  • Multiple bumps

  • Painful or swollen breasts Singular lumps

  • Ulceration

  • Yellow discharge or pus from the nipple

  • One of the most common breast cancer indicators in your furry child is a mass (lump) in the mammary glands. The fourth and fifth mammary glands (glands closest to the groin) are most commonly affected. The mass may be normal color, red or purple, soft, hard, and in some cases ulcerated.


Other systematic signs to be on the lookout for and may indicate your pup has cancer are:

  • Breathing difficulties

  • Lameness Lethargy

  • Loss of appetite

  • Weakness

  • Weight loss



Surgery is a must treatment for mammary tumors. Usually, one or more of the mammary glands are removed. If the tumor is found in multiple glands, you may be recommended to remove the entire mammary chain.

Chemotherapy may also be recommended by your vet. This is generally given to them every three weeks with an injected by an oncologist for a total of 4-5 treatments.

Unlike humans, most dogs do not lose their hair and usually have only mild side effects from the medication, such as loss of appetite and vomiting.


THESE SIGNS DO NOT 100% MEAN YOUR DOG HAS CANCER. ALWAYS CHECK WITH YOUR VETERINARIAN IF YOU ARE WORRIED! Though this is a hard topic to even consider, it is better to get your dog treatment as soon as possible for a higher chance of success.


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This entry was posted by Rachel.

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