Kingstonist’s Wizard of Paws: Even pets have breasts

Veterinarian Ryan Llera with puppy patient, Enzo.

October is widely known is Breast Cancer Awareness month for people. Well, lately it’s also become a month to raise awareness for the risk of breast cancer in pets too! Yes that’s right, Fluffy and Bella can also get breast cancer. Unlike women though, your pets can’t check themselves for lumps.

Feline mammary tumor.

Cats and dogs have multiple breasts, or mammary glands, that are aligned in two chains. Normal swelling can be noted if pregnant or nursing, but in any other case, a lump may be abnormal. After animals have been spayed, they can accumulate fat in these areas and these would non-concerning lumps. You can feel along the chain for an abnormal lump that would be at least the size of a small marble. This is when you should schedule an appointment with your veterinarian, not waiting to see if it goes away. It can only get worse if you wait until it’s the size of a lemon.

Your veterinarian will start with a general exam, then discuss some diagnostics to further evaluate the lump. Just feeling the lump is often not enough to be able to tell you everything you need to know. No, we don’t have a mammogram machine in our office. Our diagnostic plan can include a fine needle aspirate to try and get some cells to look at under the microscope, but sometimes this is not sufficient.  Alternatively, we can move forward with chest x-rays to assess for spreading of the tumor, and then surgery. Submitting the whole lump to a pathologist will give us a more certain diagnosis to be able to determine future treatment and prognosis.

Canine incision after removal. Surgery was delayed for months.

Surprisingly, we have some good statistics when it comes to breast cancer cases in dogs. It’s a 50-50 chance of the mass being benign. Unfortunately, in cats the numbers are 90% malignant and only 10% benign. Surgery can often involve the removal of the lump and the one next to it, or sometimes the entire mammary chain. Typically, when your veterinarian is talking about breast cancer in your pet, they are focusing on middle aged or senior pets. You can help your pets by making sure to spay them.  Spaying before their first heat cycle greatly reduces the risk of breast cancer.

So do your pets a favor, check them for breast lumps. And if you see a lump, don’t wait to see if it goes away… it won’t!


Dr. Ryan Llera is a small animal veterinarian at the Kingston Veterinary Clinic. Though originally from Florida, he married a Canadian (who is also a vet!) and they share their home with two cats, two dogs, two horses, and a rabbit. Dr. Llera also contributes writing to various other animal and veterinary related blogs. You can find more of his writing at, or see what else he is up to on Facebook, Instagram, or Twitter.


If there’s something you’ve often wondered or have questions about, let us know by email at [email protected].
*Please note that specific medical questions about your pet cannot be addressed and you should speak with your personal veterinarian.


Disclaimer: All columns are personally written and my opinion and may not necessarily reflect those of current or former employers.

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