About Mammary Cancer in Cats

Mammary cancer is the third most-common cancer affecting cats, according to Mar Vista Animal Medical Center, and frequently a serious condition, as 90 percent of such tumors turn out to be malignant. Since cats have eight breasts, they have many places where mammary cancer tumors can occur. Mammary cancer worsens the longer it is left untreated.

  1. Symptoms

    • The first symptoms are small, round lumps under the skin of the cat's breasts that feel as if there are dried peas or large grains of sand under the skin. The pairs of breasts that often get the symptoms first are the pair closest to the head and the pair closest to the tail. If not treated, the lumps will grow in size and number, eventually bursting open to release foul-smelling fluid.

    Treatment

    • The most common treatment is surgical removal of the tumor, which often leads to the removal of the entire mammary gland in the cat. However, if the tumor is thought to be too large to remove surgically, chemotherapy can be used to try to shrink the tumor, then it can be removed surgically.

    Considerations

    • Mammary cancer mostly happens to female cats over 10 years old. Depending on general health, both surgery and chemotherapy may prove to be too strenuous for an aged cat to handle. The vet then may advise euthanasia. Treating mammary cancer in cats can be expensive. Often, a veterinary oncologist needs to administer any chemotherapy drugs because a regular vet will not know how to do this.

    Prognosis

    • The average length of time a cat survives surgical removal of a tumor is two years, but can be as long as three years. If the cancer has spread to the lymph nodes, then the survival time goes down to six months.

    Prevention

    • The best way to prevent mammary cancer in cats is to get the cat spayed before she goes into her first heat. Spaying removes the surges of progesterone thought to be one of the causes of breast tumors in cats. According to Mar Vista Animal Medical Center, early reduces a cat's chance of developing mammary cancer by 91 percent. Spaying in the first and second heats can still reduce a cat's chances to 86 percent. "Cat Owner's Home Veterinary Handbook" advises owners of unspayed female cats over the age of three to check the cat's breasts once a month for lumps or sores.