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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Breast Cancer Signs in Dogs: What to Look For and How to Think About Mammary Cancer

Updated: December 16th, 2019


Finding a lump on your dog’s breast is not good: Learn how to examine your dog for breast cancer and when to head to the veterinarian.

Breast cancer … in dogs? Can dogs even get breast cancer? Yes, they do.  We don’t call it by the same name; in dogs, we call it mammary cancer. But because the mammary gland is the bulk of the breast, and the disease is very similar, mammary cancer is, in fact, dog breast cancer.

Thankfully, breast cancer in dogs is not as aggressive as breast cancer usually is in humans … but it’s serious, nonetheless. For a full discussion of breast cancer, including its warning signs, treatment, and special diet considerations, please see chapter 31, which starts on page 320 of The Dog Cancer Survival Guide.

Signs of Breast Cancer in Dogs

Signs of breast cancer in dogs include the following:

  • small nodules (bumps) within the mammary tissue that feel like little BBs under your fingers
  • larger nodules within the mammary tissue, still under the skin
  • bloody discharge from the nipple
  • straw-colored discharge from the nipple
  • pus-like discharge from the nipple
  • larger, deeper growths in the mammary tissue that protrude visibly and can be seen as lumps

Want to learn more about mammary tumors and how to treat them? Get the Dog Cancer Survival Guide, and flip to Chapter 31

Spaying and Breast Cancer

Veterinarians often advocate early spay for females because it can prevent breast cancer later on. This is usually done before the first heat comes at about six months.

And it’s true: female dogs who have been surgically sterilized before their first heat, which is usually around 6 months of age, usually live essentially free of breast cancer.

As the spay age increases, this protection drops.

Sounds good, right? Well, yes, as far as breast cancer goes. But you should also know this: early spay and neuter before the first heat is associated with increased risks of other types of cancer.  Those other types include the very aggressive osteosarcoma and transitional cell carcinoma.

This is why we debate whether early spays help avoid cancer. The evidence is mixed. Early spays almost completely eliminate breast cancer, which is nice. But early spays INCREASE the risk of more aggressive cancers.

Found a Lump on Your Dog’s Breast? Get It Checked.

The most critical thing to remember is that if you have a female dog who has a bump in the area around the teat (nipple), please get it checked.

Many of these growths are life-threatening.  And if you have a female dog who is not spayed (intact), or was spayed later in life (at more than 6 months of age), examination of the mammary tissue of your dog may be a lifesaver.

How To Give Your Dog a Home Breast Exam

A breast exam in dogs? Yes, you heard it here first.  You should absolutely examine your dog, especially if she is intact or spayed late.

How do you do it?

First, you have to be able to see and feel her belly. Many dogs already like to lay on their sides or back.  If your dog “gives belly,” you can do her exam then … but even dogs who won’t roll over can still be examined.

Whether giving belly or standing up, here’s what you do.

First, find the mammary glands. Dogs normally have ten, two rows of 5 going down the length of the body, one on the left and one on the right. If your dog has an extra teat or a missing teat, or if they are not perfectly aligned from left to right, don’t worry. Variations are normal!

Second, use your fingers to “see” as well as feel, as instructed below. There are two separate techniques to use — so don’t skip these steps.

  • To make sure your dog is comfortable, try doing this with two hands, one on the left chain and the other on the right chain.
  • Keep your fingers flat and use the pads of your fingertips to “fan” through the mammary tissue up and down the torso, from the head to tail. Start on the first teat on both sides and work down toward the last teat on both sides, feeling for “blips” or bumps under your fingertips.
  • Still keeping your fingers flat, fan your fingers left to right, from the first set of teats to the last. You are still looking for those little blips or bumps.
  • Next, use the second technique, which is to gently press the mammary tissue to look for deeper bumps or lumps. On each teat, gently gather the mammary tissue between your thumb on one side and your index and middle finger on the other. Keep in mind that this could be sensitive tissue, so be gentle! Gently roll the tissue with your thumb as your fingers hold the other side. Move your thumb in a circular motion and feel for blips and bumps between your fingers.
  • Remember, you are looking for little lumps and nodules that feel different from the surrounding mammary glands.
  • Any area that is hard or different is worth having a veterinarian take a look at.
  • If you can see pus, blood, or any other abnormality on the mammary tissue, get it looked at.

How often to do an examination like this on your dog?  I suggest every month or so for female dogs above the age of 7 years.

Even if your dog had an early spay, do a breast exam every once in a while for your own peace of mind. It’s well worth the few minutes.

Treating Breast Cancer in Dogs

Breast cancer in dogs is best treated with a combination of different Full Spectrum steps.  In my patients, I use surgery, dietary changes, Apocaps, deliberate efforts to increase life quality, reduction in body fat (a risk factor for mammary cancer), immune-boosting and anti-metastatic supplements, touch therapies, and more.  As a rule, this cancer does not respond very well to chemotherapy.


Dr D

Spay/neuter and the association with cancer in dogs: part one

Discover the Full Spectrum Approach to Dog Cancer

Leave a Comment

  1. lisa angelos on May 17, 2020 at 9:09 am

    I just found a more than swollen gland on my dogs stomachs and she yelped when I picked her update how I found it is this something I should rush her to vet right away????????

    • Molly Jacobson on May 19, 2020 at 12:38 pm

      Aloha Lisa, yes, please call your veterinarian and see what they think about that. Depending upon where you live, they may want to assess a little over the phone before you come in for a socially-distanced vet visit 🙁 Best of luck!

  2. Sandi Davis on February 16, 2019 at 11:58 am

    If it is cancer does the area become hot and red and does it cause them to have a hard time breathing

  3. Sarah Drysdale on February 2, 2019 at 11:43 am

    My Greyhound has started to n6

  4. Nicole on January 16, 2019 at 8:55 pm

    Can you send me a picture of what the discharge from the nipple would look like as far as the puss or the straw color because my dog is lactating and I’m not sure the color difference from that and milk

    • Dog Cancer Vet Team on January 17, 2019 at 7:53 am

      Hello Nicole,

      Thanks for writing! We here at customer support cannot offer you medical advice, because we’re not veterinarians. For something like this, you will have to consult with your vet. They know your dog, and her health situation, and will be able to help you figure out the color difference.

      You could ask the members in the Dog Cancer Support Group on Facebook if they have any information/pictures/experience with regards to your question 🙂 Even though the Dog Cancer Support Group is for the Dog Cancer Survival Guide readers only, the admins will accept your request and grant you provisional membership to talk with members and give you time to get the book. You can find the Facebook Support Group here.

      We hope this helps!

  5. Jonnine Bloss on January 15, 2019 at 11:16 am

    I went To take my 9-year old Frenchie in to get Spayed and found out she has breast cancer. Would you recommend that she gets spayed at this age. I rescued her about 7 years ago and guessing she’s 9 now. I dont Know what to do.

    Please advise.

    • Dog Cancer Vet Team on January 16, 2019 at 8:04 am

      Hello Jonnine,

      Thanks for writing, and we’re sorry to hear about your girl. As we’re not veterinarians here in customer support, we can’t offer you medical advice. We can however, provide you with information based off Dr. Dressler’s writings 🙂

      As Dr. writes in the article above, “It is still debated as to whether spaying once mammary cancer has developed in dogs actually help the problem, and the evidence over the last couple of decades is mixed at this time.” So, talk to your vet, and see if they have any thoughts as to whether this would be a good option for your girl, as each dog, and their health situation is different 🙂

      In the Dog Cancer Survival Guide, Dr. D writes that there are many things that you can do to help your dog with cancer, such as surgery, diet, nutraceuticals, mind-body strategies and immune system boosters and anti-metastatics. Here’s a link to the Dog Cancer Diet PDF that readers of the blog can get for free : He does say in this article that you should reduce your dog’s body fat as this can be a risk for mammary cancer. He also writes that mammary cancer does not respond very well to chemotherapy as a rule.

      If you are interested in Life Quality, there are many things that make a dog’s life great, from their perspective, and Dr. Dressler created a Joys of Life scale to help readers determine their dog’s quality of life. You can find out more on life quality in the articles below :

      If you’d like to try some mind-body strategies, Molly wrote an amazing article on Magical Thinking and Dog Cancer that you may find helpful!

      Check with vet, and see if they have any thoughts as to whether spaying your girl would be a good option with regards to her current health situation. You could also ask about diet, and see if they can help you tailor the Dog Cancer Diet to suit your girl’s dietary needs and health 🙂

      We hope this helps!

  6. Brian Sudderberg on January 10, 2019 at 1:54 pm

    My 4 year old Great Purinease is not fixed and recently while in heat suddenly had a mass on one of her breast. It quickly grew to just under the size of a baseball. Once she was no longer in heat it disappeared as quickly as it came. Our Vet is jumping right to a $2500 surgery. Is there any other explanation other than potential Cancer?

    • Dog Cancer Vet Team on January 11, 2019 at 7:29 am

      Hello Brian,

      Thanks for writing! We’re not veterinarians here in customer support, so we can’t offer you medical advice. However, we can provide you with information based off Dr. Dressler’s writings! 🙂

      Vets aren’t able to tell what a lump is just by feeling them– they either have to do a fine needle aspirate, or a biopsy. In this article, Dr. Sue writes that if a lump has been there for over a month, or is larger than 1cm, get it checked ASAP.

      Talk with your vet, and see if that is an option for your dog. If you are still unsure as to what to do, check our this article on treatment plan analysis. You could also get a second opinion, if you are unsure if surgery is something you want to put your dog through. Here’s an article on where you can look for a second opinion:

      We hope this helps! 🙂

  7. Stephanie Cornell on April 20, 2018 at 8:09 pm

    My girl turned one two weeks ago. A couple weeks ago I noticed small round “lumps” under her nipples. Well they have been getting bigger almost daily. I went to work the other night and when I came home all of her “breasts” we hanging if you will. Definitely a noticeable difference from the night before. I don’t have much extra money for a vet but if need be I will get her there.The first thing I thought was breast cancer of course I’m hoping I’m wrong. What is any other opinions and has anybody else had anything similar. Oh and there is ABSOLUTELY POSITIVELY NO way she’s pregnant.just had to throw that out there.

  8. christine nipple on November 28, 2017 at 8:11 am

    I have a dog that has a small lump by her back tit and clear discharge when gently squeeze her tit. doesnt seem to bother her

  9. margo benjameen on October 20, 2017 at 2:07 am

    Hi , what had happen to her after ? As I have same issue with my dog

  10. Amber Drake on October 9, 2017 at 5:01 pm

    Hello, Rebecca. Please take your dog to your veterinarian and get that lump checked out. It absolutely could be cancer, you want to know for sure!

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