Guest blog by Louise Murray, DVM DACVIM, Vice President of the ASPCA Animal Hospital and author of “Vet Confidential: An Insider’s Guide to Protecting Your Pet’s Health”
Many pet parents don't realize that pets can also suffer from breast cancer. In veterinary medicine, these tumors are referred to as mammary gland tumors, and are unfortunately one of the most common kinds of cancer in pets.
Cats generally have eight mammary glands, arranged in four pairs. Dogs usually have 10 glands arranged in five pairs, though the number varies with the size of the dog. Mammary gland tumors in dogs and cats can be benign or malignant. In cats, around 90% of mammary gland tumors are malignant. In dogs, approximately 50% are malignant.
How can mammary gland tumors be prevented in dogs and cats?
The most effective way to prevent mammary gland tumors is to have your pet spayed before she ever goes into heat. There is a myth that animals should have one heat cycle (or give birth to one litter) before they are spayed. In fact, dogs who are spayed before their first heat cycle are 2,000 times less likely to develop breast cancer! Cats spayed before their first heat are 91% less likely to develop breast cancer than unspayed cats. After just one heat cycle, the risk rises in both dogs and cats.
Detecting mammary gland tumors
Just like in people, performing mammary exams in dogs and cats is very important. Early detection is key. If your dog or cat allows, perform a mammary exam on her once a month. Gently feel the tissue under and around each nipple, "rolling" the tissue between your fingers. Very small mammary tumors often feel like a little BB pellet under the skin. If you feel even a tiny lump or firm area, bring your pet to the veterinarian immediately.
There is evidence that canine mammary tumors can become malignant over time, so prompt removal is essential.
Treatment of mammary gland tumors in pets
The main treatment at this time is surgical removal. Depending on the situation, your pet may need to have the affected mammary gland, several mammary glands, or all the glands on that side of her body removed. The tumor that is removed will be sent to the lab for a biopsy to tell you if it is benign or malignant. If the tumor is malignant, your veterinarian may refer you to a veterinary oncologist for consultation.
For more information about keeping your pet healthy, please visit the ASPCA Animal Hospital.
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