What is Breast Cancer?
Breast cancers in dogs are often referred to simply as mammary tumors. This disease usually strikes approximately one in four unspayed female dogs. Females spayed before their first estrus cycle reduce the chances from 25% to .05%. If spayed after their first heat, but before the second, the risk of future breast cancer is approximately 8%. Half of the mammary tumors found in canines are benign, and of the half that are 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.
Breast cancer in canines is relatively common, occurring in approximately 25% of unspayed female dogs.
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Symptoms of Breast Cancer in Dogs
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 canines. The majority of tumors are found near the mammary glands closest to the back legs. Signs can include:
- Bloody discharge or pus from nipple
- Multiple bumps
- Painful or swollen breasts
- Singular lumps
- Ulceration
- Yellow discharge or pus from nipple
Systemic symptoms that might indicate cancer could include:
- Breathing difficulties
- Coughing
- Lameness
- Lethargy
- Loss of appetite
- Weakness
- Weight loss
- Enlarged lymph nodes
Types
Several types of cancer can affect the canine breast or mammary gland. These can include:
Adenoma - A benign tumor of glandular origin. Although adenomas are considered to be a benign tumor, they can occasionally develop into malignant tumors.
Carcinoma - Carcinomas are generally malignant growths made up of epithelial cells. Common carcinomas in canine breast cancer include adenocarcinomas and inflammatory carcinomas.
Carcinosarcomas - These are tumors that are made up of both epithelial cells and cells from other tissues.
Fibroadenoma - Benign, painless tumors that are a combination of skin and connective tissues. These tumors tend to be mobile within the breast tissue.
Sarcoma - Malignant tumors made up of bone, cartilage, or fat cells. Sarcomas are an infrequent cause of breast cancer in canines.
Causes of Breast Cancer in Dogs
The causes of cancer are not well understood in either humans or canines. The causes of breast cancer in dogs may have a hormonal component as spaying your female dog before their first heat nearly eliminates the possibility of developing mammary tumors. Genetics also play a factor as certain breeds seem to be predisposed to developing breast cancer. Dog breeds that may have an increased chance of developing mammary tumors include:
- Boston Terrier
- Brittany Spaniel
- Cocker Spaniel
- Dachshunds
- English Setter
- Fox Terrier
- German Shepherd
- Pointer
- Poodle
Although the vast majority of dogs that develop cancer of the breast are unspayed females over the age of 2, this is not always the case. Although it is exceedingly rare, both puppies and male dogs have been known to develop canine breast cancer. When breast cancers arise in either of these demographics, the prognosis is generally grave.
Diagnosis of Breast Cancer in Dogs
Your veterinarian will most likely start your appointment by palpating the mass or masses and collecting data regarding their size, hardness, and mobility. Information about your dog’s health history, including applicable information about your animal’s last heat cycle, current medications your pet is on, and information about pregnancies or pseudo-pregnancies will be collected. X-rays and ultrasound may be used to visualize the spread, but they may not identify any microscopic dissemination of the cancer cells.
The veterinary oncologist will usually recommend a fine needle biopsy of any tumors, and may recommend the same procedure for the lymph nodes. General testing is done to check for any concurrent disorders, and a complete blood count, urinalysis, and blood chemistry profile will be used to evaluate the condition of the patient. This is done to ensure that the animal is healthy enough to undergo surgery and the anesthesia required. A biopsy of the tumor, after surgical removal, is usually necessary for a definitive diagnosis.
Treatment of Breast Cancer in Dogs
The first course of action, in most cases, is the surgical removal of the tumor itself. In some situations, just the tumor and a small area around it require removal, but in many cases, the amount of tissue excised is greater. Many veterinary doctors will recommend the removal of all of the mammary tissue, as well as the lymph nodes that they drain into. This is not as invasive a procedure for canines as it is for humans, as the underlying muscle tissue is unaffected in canines. If your female dog is not already spayed, this may be done at the same time as the excision of any mammary tissue.
Although the role of ovariohysterectomy in reducing further cancers is controversial, it may help prevent related illnesses or infections of the uterus and ovaries and make any new tumor growth more apparent as any remaining mammary tissue shrinks after spaying. Some tumors may be harder to remove than others, and regrowth may appear, particularly with sarcoma type tumors. Surgery itself is generally effective in removing cancer, and chemotherapy and radiation therapies are not generally as effective in canines as in human patients. These treatments are generally reserved for tumors that have metastasized, are inoperable, or have a high chance of spreading.
Inflammatory mammary carcinoma is usually treated differently than the other tumors of the breast. Neither surgery nor chemotherapy treatments are effective in treating this kind of cancer. The prognosis for dogs with inflammatory mammary carcinomas are poor, but radiation therapy and NSAIDs are helpful in relieving the associated pain.
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Recovery of Breast Cancer in Dogs
Recovery from radical surgery is much shorter in canines than it is for humans, with the majority of healing occurring within two weeks from the surgery. It is important to provide the patient with a calm, quiet space to recuperate in when they return home.
Other than spaying your female dog early, the best way to protect your dog from developing breast cancer in the first place is much the same as in humans. Regular tactile examinations of the 8-10 mammary glands, feeling for lumps or bumps with your fingers, are recommended monthly for any dog with risk factors. This would certainly include any unspayed females over the age of 2, as well as any females that were spayed later in life, or who’s early medical history is unknown.
Breast Cancer Average Cost
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Top
Breast Cancer Questions and Advice from Veterinary Professionals
Maltese
Savannah
9 Years
8 found this helpful
8 found this helpful
My pet has the following symptoms:
Bumps
My 9/10 year old Maltese had mammary tumors removed in April 2017, the vet was not able to remove them all at once due to some issues mypet was having with anesthesia and removed the rest in August 2017. She had some more spots appear underneath her fromt right leg, center of her breast bone and then another few at her lower mammary glands. We have been told it was cancerous previously and this time there was a black tar-ish like goo inside of the tumors. Do we assume the cancer has more than likely spread all over?
March 9, 2018
Answered by Dr. Michele K. DVM
8 Recommendations
Thank you for your email. I wouldn't assume the worst, no. Mammary tumors can be benign, or malignant, and may or may not grow or cause problems. It would be a good idea to have chest x-rays to rule out metastasis, but oftentimes, surgical removal of mammary tumors can be curative. If you are noticing new lumps that Savannah is developing, it would be best to have her seen and examined by your veterinarian to determine the best course of action. I hope that she does well.
March 9, 2018
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Maltese
Niki
11 Years
8 found this helpful
8 found this helpful
I recently found a small lump on my 11 year old Maltese it is the size of a pea, what is recomended to have it removed? She doesn't show any signs of slowing down, lost of appetite or has any issues with going out. She is still very bouncy and happy and doesn't seem to be in pain. The lump it self is just a little round bump under her skin close to her breast.
I understand that 70% are not malignant tumors. So is it really wise to operate and have it taken out? or shall we wait and see. Is it true that if it is cancer buy cutting into it, it will cause for the cancer to spread faster? And if we wait what are the pros and cons?
Feb. 26, 2018
Answered by Dr. Michele K. DVM
8 Recommendations
Thank you for your email. It is best to have any mass in the mammary tissue removed as soon as possible. It may be benign, but even benign tumors can grow, ulcerate, and cause problems. It would be best to have her examined by a veterinarian, as they can see her, assess the mass, and give you can idea as to what the best treatment might be. I hope that she is okay.
Feb. 27, 2018
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mix breed of lab and Pomerania
Moni
14 Years
2 found this helpful
2 found this helpful
My pet has the following symptoms:
Swelling
Puss
Hello my dog name is moni, her age is 14yrs, she went under uterus operation because some kind of white liquid was coming out from her urine part, then later vet told this is uterus cancer and vet removed that part, after 2 years we found lump on her breast region, and pus is coming out of that and today we took her to hospital, VET told that is breast cancer, and here is her report, please tell what can be done?
TOTAL WBC COUNT(TC) AND DIFFERENTIAL WBC COUNT(DC)
TOTAL COUNT 14,000 cells/cumm
NEUTROPHILS 95%
LYMPHOCYTES 03%
EOSINOPHILS 01%
MONOCYTES 01%
BASOPHIL 00%
Hb 14.2 GM/DL
INDIRECT BILIRUBIN .10mg/dl
BLOOD UREA 49.0 mg/dl
Jan. 16, 2018
Answered by Dr. Michele K. DVM
2 Recommendations
Thank you for your email. Without more information about the mass, where it is, how big it is, and her general health, I can't make any recommendations for her. Most mammary cancers can be surgically removed, though - it would be best to ask your veterinarian what the next step is, as they have seen her and know more about her specific situation.
Jan. 16, 2018
Hi! I have Yorkshire terriers it’s female she discharging by 3 Naples blood and kind clear liquids. I’m afraid it maybe a cancer?
July 27, 2018
Dahiana M.
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Bull Terrier
Coco
5 Years
0 found this helpful
0 found this helpful
My pet has the following symptoms:
Thirsty
Inflamation
Tires Easily
My dog had a tumor which was surgically removed. Before this she was just tired, after she was very energetic and full of fun. After the surgery, she was energetic and seemed so happy as if it was gone. However, the healing process wasn't successful because she would constantly move, the stitches didn't hold on therefore the vet required us to do water thearpy. Once the wound closed, these lumps started to develop. We went to the vet and was told it was cancer. Months went by we went again and the vet told us whatever she has spreads fast. Now she's showing us symptoms that are having me worry. Are there any treatments for inflammation and these huge lumps that are spreading? Any medication recommended? Any advice?
Nov. 30, 2017
0 Recommendations
Was a biopsy taken from the first surgery? Do we know what type of cancer it was? Was your Veterinarian able to remove a good margin? There are many variables here and without knowing the specific type of tumour initially removed it is difficult to say what the next step is; chemotherapy may have been needed after surgery to prevent recurrence. A biopsy of one of the masses should be done to determine what you’re dealing with. Regards Dr Callum Turner DVM
Nov. 30, 2017
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Irish Wolfhound
Hera
9.5
2 found this helpful
2 found this helpful
Our 9 year old Irish Wolfhound was diagnosed with mammary cancer in July and we decided it was best to just let her live out the rest of her days, instead of putting her through surgery that she may not wake up from. We are noticing one of her larger Mets is leaking a redish pink watery fluid and are wondering what could be causing this, and if maybe taking her into see her vet is required. I'm just always worried she is suffering and we do not realize it because she is so mellow.
Nov. 4, 2017
2 Recommendations
There are various reasons why some pink fluid (most likely blood mixed in) is coming from a mammary mass; this would be something to check in with your Veterinarian about since it may be marking another step in the overall condition. In the meantime just keep cleaning the area until you visit your Veterinarian. Regards Dr Callum Turner DVM
Nov. 5, 2017
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Samoyed
kondi
7 Years
0 found this helpful
0 found this helpful
My pet has the following symptoms:
Swelling Along Breast Area
Hi my dogs name is Kondi and she is 7 years old, my vet informed me that she has breast cancer and i am not sure if he is right, how can i share photos to show you it? Please i need help
Breast Cancer Average Cost
From 367 quotes ranging from $3,000 - $10,000
Average Cost
$8,000
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