Mammary cancer in cats is the third most common type cancer seen in this species. This type of cancer is very aggressive and hard to treat as it spreads quickly.
Mammary Cancer in Cats Explained
Female cats generally develop mammary cancer—malignant adenocarcinomas—when they are about 10 to 14-years-old. The risk of developing this cancer is twice as high in cats that are not spayed at a very young age, and this condition is seen more in Siamese cats than in any other breed. Adenocarcinoma tumors are very aggressive and are known to spread to a cat's lungs and lymph nodes.
Symptoms of Mammary Cancer in Cats
One of the unfortunate things about mammary cancer in cats is that a cat will not usually display symptoms until the cancer has spread. One of the first symptoms seen in cats with this type of cancer is a hard lump (tumor) that can be moved around under the cat's skin or muscle. The tumors are usually found in the mammary glands located towards the front. They may feel as small as a granule of rice or a pea when the tumors first develop, but they will grow larger if left untreated. It's not unusual to find lumps in multiple mammary ducts. A cat with mammary cancer will not have a big appetite, will lose weight, feel weak, and have hind legs that are inflamed.
A cat can also have a fever, an infection, bruising, swelling in her mammary ducts, and be in a lot of pain. One may also find the ducts to be dilated. In more extreme cases the skin around the ducts may be found to be bleeding, secreting a yellowish fluid, or the skin is necrotic. The skin on the area over which the cancer resides may become red and ulcerated, causing a lack of mobility. As a result, a cat may try to groom herself in that part of her body obsessively and may even have an offensive odor if the ducts are infected or necrotic.
If the cancer has spread to a cat's lungs, she may have difficulties breathing, a cough, may be more lethargic than usual and tire quickly.
Treatment of Mammary Cancer in Cats
When a cat is diagnosed with mammary cancer, a veterinary oncologist will try to surgically remove the growths. If surgery isn't possible or the tumor is too large to remove completely, a cat will receive chemotherapy treatments in an attempt to shrink the growths so they can then be removed. When the cancer is found in its advanced stages or is deemed too difficult or expensive to treat, a veterinarian may recommend comfort care for a cat to help improve her quality of life until she passes.
About 80% of mammary tumors in a cat are malignant and the prognosis for a cat with mammary cancer is poor. With early intervention and treatment, a cat's timeline can be extended.