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Breast Cancer in Dogs

October is Breast Cancer Awareness Month, but chances are dog owners have no idea that their dogs can actually get breast cancer. The bad news is that breast (mammary) cancer in dogs is common; the good news is that the disease can be treated successfully if caught early.

According to veterinarian Dr. Race Foster, the most common type of tumor in female dogs is the mammary tumor—especially in (unspayed) dogs between the ages of five to 10 years-old. There are male dogs that do develop breast cancer and, sadly, their prognosis is not good because this type of breast cancer is very aggressive.

Signs of Breast Cancer in Dogs
Similar to human breast cancer, mammary tumors in dogs can range in size. Breast tumors in dogs often grow quickly with an irregular shape. These malignant tumors can also cause bleeding and ulceration. However, if your dog’s tumor does not exhibit these signs, that does not mean your dog is free from breast cancer; small tumors that have been present for a while can suddenly grow aggressively as well. As with most other types of cancer, once malignant tumors in dogs start to grow, the cancerous cells can spread to other parts of the body.

If you find a lump on your dog, do not wait to go to the veterinarian. It is always best to play it safe and have your dog examined by a licensed veterinarian who will perform a biopsy. Half of all mammary tumors in dogs are benign, but do you really want to play guessing games when it comes to your dog’s health?

Treatment of Canine Breast Cancer
Treatment of a malignant tumor usually involves surgery. Similar to breast cancer in humans, dogs will either have just the tumor removed or the entire mammary tissue along with lymph nodes. Dogs’ mammary glands are different than humans in that they are outside of the muscle, so the surgery is not as radical. Dr. Race Foster suggests that unlike humans, chemotherapy and radiation in dogs are not successful.

Canine Breast Cancer Prevention
The best way to prevent breast cancer in female dogs is to spay them before they go into heat for the first time—just another benefit of spaying. By doing this, dog owners can practically eliminate the chances of their dog developing mammary cancer.

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Submitted by Anonymous | December 28 2012 |

I find it odd that you don't credit your sources or research on this topic. I imagine it is because you did not do any nor have a basic knowledge of the human anatomy - "Dogs’ mammary glands are different than humans in that they are outside of the muscle, so the surgery is not as radical." Last time I checked, mammary glands are located outside the muscle in humans too. Do you even know what a radical mastectomy is and what it involves? Did you bother to interview any animal oncologists? Radiation and chemo can extend the dog’s life by 1 – 2 yrs depending on the stage of cancer and what kind of cancer. How do you not even bring up Canine Cancer Awareness Month? By the way, you also need to brush up on your grammar.
Shame on BARK for publishing erroneous information on such an important topic.

Submitted by TrishB | February 18 2013 |

To anonymous:

Stating "According to veterinarian Dr. Race Foster..." isn't a good enough source?

Your criticism sounds unnecessarily strident. Many feel that subjecting a dog to harsh chemo and radiation just to buy them a year or two is not a good tradeoff. I've had breast Ca with surgery, chemo and rad and I wouldn't have gone through it myself if it promised me just another couple of years. It's pretty brutal. But to subject a dog to it, well, I love my mutts too much to put them through that.

Submitted by Maxx's Mom | February 4 2013 |

My 14 yr.old Dacshy is undergoing treatment for allergies .. He received most of his shots , used anti-histamine and prednisone but he only got "itchier" and red ..

While nearing th end of the "first" treatment he developed a growth that looked like a pimple under his armpit .. Within a few days it grew larger and redder ..

Went to the vet and discovered that one of his nipples which was always inverted also became inflammed.. I question my decision to put him thru the vaccines.. I am worried now that he has mammary cancer..

Can someone with real knowledge reply ?

Submitted by yvonne wolfe | February 8 2013 |

our misty littlebear was 12 years old our vet told us she had breast cancer but also told us because of her age she would not make it through surgery this was not even 2 months before we took her back to him just to have him say her heart was bad and she was in alot of pain and she needed to be put down out of her missery my husband and i cant understand how it all happenend so fast for two days misty barely ate or drank any water and what she did she brought back up she started having seizers and one lasted for a half an hour she lost partial use of her left hind leg we get her remains back today it was only three days before her passing that we lost her sister cherokee to heart failure two of our children in three days time cherokee was wednesday jan-30-2013 at 9:17 am and misty was saturday feb-2-2013 can someone please help us understand how misty looked so healthy and now shes gone my husband is taking this so very hard

Submitted by Sharon | May 14 2013 |

My heart goes out to you for your loss of two of your precious babies. It is so easy to second guess the vets and yourself. I have been going through the same excruciating heart break. I lost my Fancy Darling 4-13-13. She had a small lump and she was twelve.. We had our mobile vet come out to look at her when we first noticed the small lump and was told to leave it alone and it was nothing to worry about at that time. When I took one of my dogs in for an ear infection to our local hometown vet I was telling her about Fancy having a lump and she suggested we bring her in to have it checked out and that twelve was not too old for a surgical procedure she had removed masses from fifteen year old dogs..and had a high survival rate.So,I agreed and was with good intentions prepared to take her for her exam and not making excuses but, everything that could go wrong did.. My elderly aunt became ill and between taking her to hospital and doctor appointments..we put it off. Then one week I noticed her lump had turned into a huge mass into both front and back legs.. I was distraught and angry with myself!! I took her in the day I noticed it had spread..we went through so much trying to save her. Then her blood woud not clot and we did a blood transfusion at the same time my husband had to have gall bladder surgery. After the blood transfusion she seemd to be doing better but, then died the next morning..while I was at the hospital with my husband.. It was devastating. I am still trying to forgive myself for waiting..Dogs can be so stoic..

Submitted by Shazzy | July 29 2013 |

So.....while cleaning up after dinner having a chat with my husband and brother in law.. My brother in law out of the blue goes... Kara has breast cancer... Feeling numb,since I love this beautiful dog. I asked him what did the doctor say? Can they fix her?.. Holding my breathe.. he says," Nothing they can do. She has 20% chance to live if she has surgery." My heart just fell in a thousand pieces.I am a supporter of breast cancer and to hear this broke my heart. An animal deserves just as a person a day to have awareness!!!!! It will do good to spread the awareness to people who as well who is suffering and the supporters of breast cancer.It is about to spread the awareness.. not that they are canine. I believe.. we treat animal's the way you want or wish god is to you. You love them just as he will you.. It is sad if you do not believe it is the same.. if you do not,then you do not have a heart....Have some compassion..

Submitted by Lisa | October 8 2013 |

A friend of mine's pitbull was diagnosed with breast cancer, fortunately surgery removed the whole tumor and she was not required to have chemo or radiation. She lived about two years after then passed for other reasons. I also had a pitmix that had fibro sarcoma, this was the first I learned that animals can get cancer, after my vet felt he did what he could do I took him to an oncologist. He was diagnosed at 12 and lived for four more years, and he was not a small dog. We were able to get into a study and try a new medication to stop the tumor from growing. Sometimes chemo, radiation or surgery is not always the answer, don't be afraid to ask your vet about alternatives.

Submitted by Debbie | November 11 2013 |

I have a beagle that is 13 years old. She developed a tumor near groin that appeared to grow and double in size about every three months. Had taken her to vet as soon as the lump first appeared and was told she had mammory cancer in more than one spot and probably only has about 6 months to live. Decided at her age that I wasn't going to put her through surgery or chemo. The tumor keeps growing and is now the size of a baseball hanging down from her groin/lower stomach area. She does not appear to be in any pain and acts herself in every way. It has been 2 and half years now since told she only has 6 months. I have been actually making my own medicine. I went into the bush and looked for tumors on a birch tree. Cut it off with an axe and boiled the black pieces in boiling water, until the water turned like dark tea. Then took dog biscuits in pieces and soaked in the homemade tea. This seemed to improve my dogs health, and assisted with any bladder problems she had due to the tumor. I am not a doctor and am now aware she is past the stage spending a ton of money to a vet. Doing anything and everything to just keep her active and happy. Think she just might be around for another couple of years.

Submitted by Rosemary | November 19 2013 |

Can u tell me more. My ten year old beagle is in the same boat. Had a mammary tumor removed 2 weeks ago and another appeared last week. Told she has 5 months. Cancer also in her lymph nodes. She sleeps a lot but still eats well ad gets around. Any suggestions?

Submitted by LUCY | April 22 2014 |

Hi there. Can you please tell me more about this tea you make? Thank you!

Submitted by Jotham Miller | June 6 2014 |

It sounds like the tea is made from a mushroom called Chaga. It's supposed to have powerful cancer fighting abilities and you can make it yourself or get it on Amazon.

Submitted by Patty | May 14 2014 |

My 13 year old golden was diagnosed 6 months ago and has two rapidly growing tumors, one ulcerated. She is eating,drinking and moving around great but the smell and leakage is unbearable. We are so torn as what to do and surgery to remove it has the vet worried she won't come out of it. Any opinions or suggestions? We have a diaper over it with a shirt keeping it on right now

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