DOGS AND CATS CAN DEVELOP BREAST CANCER TOO!
By Dr. Kerri Suhr, D.V.M.
In women, one in eight or nine will develop
breast, or mammary, cancer. In dogs that have not been spayed, that number
jumps to one in four. In intact female cats, mammary cancer is
the 3rd most common cancer. Most dogs and cats that develop breast
cancer are intact females (have never been spayed), or females spayed after the age of 2-3 years,
and are around 10 years of age at diagnosis. In cats, Siamese cats are
more prone to have tumors show up at a younger age than other breeds.
Male dogs and cats can also develop breast cancer, but it is not very common.
This sounds scary, but there is some good news! In dogs, if a female is spayed before her
first heat cycle ( which usually occurs between 8 months to a year of age)
there is almost no chance of her developing breast cancer. With one heat
cycle, the percentage increases a little - to about 7%. With multiple heat
cycles, the incidence rises to one in four females developing cancer.
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| Small mammary tumor in a dog. |
If female cats are spayed before they
are 6 months old, they have a 91% lower incidence of mammary cancer. They
have an 86% lower rate of cancer if spayed before 1 year of age. Studies also show that there is an 11% reduction of breast cancer if spayed before the
age of 2 years. Spaying after the age of 2 does not seem to lower the risk of
mammary cancer in cats. Having kittens does not seem to affect these numbers one
way or the other.
Spaying your pet early is the best way to help prevent the development of mammary cancer later in life!
Spaying your pet early is the best way to help prevent the development of mammary cancer later in life!
Even though spaying later in life or
after tumors have been detected does not seem to decrease the risks of
developing mammary cancer, most of these cancers are at least early in the
disease responsive to hormones. It is thought by some to be
advantageous to still spay them, as this may help them have a longer survival
time after surgery.
If your pet happens to develop a mammary tumor, there are some important facts that you need to know:
50% of mammary tumors found in dogs are
malignant, which means they are invasive forms of cancer with the potential to spread. About 50% of
malignant tumors of mammary glands have already spread ("metastasized") by the
time they are detected.
The other half of mammary tumors in dogs are benign (noninvasive). In these cases, removing the tumor surgically will cure the problem.
Unfortunately, in cats, about 90% of
mammary tumors are malignant. These tumors in cats have a very aggressive nature, and spread quickly to lymph nodes and
other surrounding mammary glands. They can spread to the lungs and other tissues as
well.
What should you do if you suspect a mammary tumor in your pet?
If you feel a hard lump in the skin
on the underside of your dog or cat, call your veterinary office to schedule an appointment for further diagnostics. Your pet will need to be examined. Tests
are usually run to determine whether cancer has spread
to the lungs and lymph nodes, and to determine the overall
health of the animal. This usually includes x-rays, cytology (looking at the cells under a microscope) and
bloodwork. Fine needle aspirates that show cells under the microscope can help to determine if the mass is indeed arising from breast tissue, but this test is not great at determining a prognosis or continued treatment plan for
mammary cancer. In most cases, a surgical removal ("biopsy") with histopathology is
necessary to determine what type of cells are present and if it is malignant or
benign. This means the mass is removed and is sent to a
laboratory to be evaluated by a veterinary pathologist.
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| Mammary tumor cells under a microscope. |
The biopsy will provide a lot of valuable
information. The pathologist will determine the type of tumor and whether
it is benign or malignant. This gives an idea of prognosis and the
best type of treatment. The biopsy also will determine if the margins of
the skin and tissues around the tumor are clean. (No signs of cancerous cells extending
out to the edge of the removed mass.) This will determine whether a second
surgery is necessary to remove remnants of abnormal cells.
Treatment recommendations depend largely
upon the type of mammary cancer, the size of the mass, whether it has
metastasized, and the overall health of the animal. Removal of the mass
with clear margins is often curative for benign masses. For more
aggressive tumors and tumors removed without clean margins, further surgery, chemotherapy and radiation therapy are adjunct therapies available after the initial
surgery in dogs. In cats, aggressive surgical removal of the mammary
chain can lead to patients being cancer-free for up to a year in 50% of cases.
Every pet with mammary cancer is different, and no two cases are alike! Your veterinarian is your best resource to help guide your decisions for your pet's care. If you are concerned about a lump you have found in your pet, call your favorite Noah's veterinarian to schedule an appointment.
references:
Chemotherapy for Malignant Mammary Carcinoma ACVIM 2013;
Antony S. Moore, BVSc, MVSc, DACVIM(oncology)
VeterinaryPartner.com The Pet Health Care Library, Wendy C.
Brooks, DVM, DipABVP
I had no idea that it was so common in pets. I ended up needing the services of a animal hospital in Kansas City for my dog who was shedding a lot more then usual. Luckily it was nothing major, but now I want to make sure she doesn't have breast cancer. Thanks for sharing this.
ReplyDeleteIts really a nice and knowledgeable post you have posted. which help most of the people. Thanks for sharing.
ReplyDeletedog microchip reader
Sadly, this happened to my golden retriever. I had a great animal clinic in South Colorado Springs, CO. They were so kind and helpful. People, please get your pets checked and make sure you are taking precautions.
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