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Breast Cancer in Pets

In honor of Breast Cancer Awareness month, I thought I’d research a topic that many people don’t know a lot about; breast cancer in pets. Most people are aware that pets can get many different types of cancer, as it is the leading cause of death in older pets. lazy cat

Among pets, dogs appear to have the greatest prevalence of breast cancer; it is estimated that 1 in 4 unspayed female dogs will develop a form of breast cancer. Other animals, such as cats, rats and other small mammals can also suffer from breast cancer, known as mammary cancer. About half of dogs who are diagnosed with breast cancer have a malignant form of cancer, but if caught early enough both types of cancer can be treated through removal of the tumor and chemotherapy. Breast cancer can be prevented in most pets simply by having them spayed (and that helps with pet overpopulation too!).


Breast cancer in cats is less common, it occurs in about 1 in 4000 pet cats, however up to 90% of tumors found are malignant. The treatment options remain the same as in dogs, but have been reported as less effective.

It is suggested that unspayed pets develop breast cancer because of the influx of hormones their bodies undergo during and after their heat cycles. After every heat cycle a dog has their bodies undergo what is called a hormonal pregnancy, even if your pet isn’t actually expecting a litter. The hormones produced stimulate the mammary glands during this time period.

Screening and Prevention

Common symptoms of cancer in pets include swelling, abnormal growths or lumps, sores that won’t heal, unexplained weight loss or loss of appetite, and bleeding or abnormal discharge. Sometimes pets afflicted with cancer will also exhibit odd odors, hesitation to exercise, little to no interest in activities that used to excite them, stiffness or difficulty with breathing, urinating, or defecating. If your pet is exhibiting any of these symptoms it is imperative that you see your vet immediately to rule out cancer and other illnesses.

Cone Of ShameLuckily, preventing breast cancer in dogs and cats is pretty easy.  Spaying your pets has been shown as the most effective method for preventing mammary cancer. There is some debate on how early they should be spayed. Most research has demonstrated that spaying your dog or cat before their first heat cycle can reduce their risk significantly, but a reduced risk has been observed in pets spayed before the age of 3. Talk with your vet to determine the best age for your pet to undergo the spaying procedure.

There is also research that suggests that a dog or cat who has given birth to at least one litter of pups or kittens have lower rates of developing mammary cancer. I’m more of an advocate for spaying than suggesting this route because there are so many animals in need of homes in shelters across America (and beyond).

Even if your pet is spayed, you should perform monthly breast exams on pets over the age of 5. Roll the skin and tissue around each nipple gently between your fingertips and feel for lumps. While you are at it, ladies, give yourself an exam too! If you notice any lumps, even a really small one, make an appointment with your veterinarian to have it checked out. Early prevention is the key to increasing your pets’ odds of a successful treatment.

To further reduce the risk of any type of cancer it is important that you help your pets lead a healthy lifestyle. Provide them with nutritious and wholesome food, plenty of exercise and keep their weight in check. A yearly well-check with your veterinarian, or as often as every six months for senior pets, can also be important to catch any potential problems early on.

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About hcrotsley

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Currently an owner of 3 dogs and 2 cats, I’ve gained a plethora of pet-related experience over the years. I strive to provide the best home I can for my little terrors, and you’ll read all about our trials and tribulations as I continue down the rewarding yet rocky road of pet parenthood.

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