Mammary Cancer in Cats

Mammary cancer in cats is the third most prevalent form of the disease. This form of cancer is most common in older cats and spreads quickly if not caught early.

Symptoms of Mammary Cancer in Cats

Most female cats have eight mammary glands. The majority of cancerous tumors are found in the Thoracic mammary glands. Tumors often feel like a dried pea when first noticed and will grow to more than one-inch in diameter. Other signs that your cat has mammary cancer include:

  • Fever
  • Pain in the mammary glands
  • Swollen mammary glands

Facts about Mammary Cancer in Cats

Approximately 8 out of 10 tumors are classified as malignant adenocarcinomas. These tumors are extremely aggressive and spread quickly to other areas of the body.

Veterinarians use a grading system to categorize tumors:

  • Grade I tumors are usually beatable and most cats go on to live full lives.
  • Grade II tumors come with a 57 percent survival rate after one year following surgery, chemotherapy increases those odds.
  • Grade II tumors are hardest to fight, no cats survive these tumorous growths without surgery and chemotherapy.

Because veins connect the right and left side glands, cancer cells will pass from one mammary gland to another easily before moving to the lymph nodes and then organs. If the cancer has spread to the lymph nodes, the risk of death is much higher.

If left untreated, the cancerous growths will eventually rupture causing skin lesions. These lesions smell horrible. If a tumor reaches this point, most vets feel it is better to humanely euthanize the cat.

Cats die from mammary cancer because the tumors eventually spread to the chest and lungs making it difficult for the cat to breathe. In situations where the tumors reach the lungs, most cats will survive for no more than six weeks.

Preventing Mammary Cancer in Cats

There is one way to reduce the risk of cancer in cat's mammary glands. Have your female cat spayed while she is a kitten. Once a cat reaches two years of age, spaying does not improve the odds of the cat avoiding mammary cancer.

Siamese cats seem to develop cancerous breast tumors earlier than other breeds. While most breeds develop mammary cancer after the age of 12, many Siamese develop the cancer before their 10th birthday.

Cats that are given drugs that contain synthetic hormones have a higher risk for developing mammary cancer. If your vet suggests a drug that acts as progesterone to treat dermatitis or a behavior disorder, it's best to look for alternative solutions.

Perform Regular Chest and Abdomen Examinations

You should stroke your cats belly and chest regularly looking for lumps. If the tumor is less than two centimeters when it is surgically removed, most cats go on to live another 4.5 years. Tumors that are larger than an inch when removed greatly decrease the median survival time to half a year.

Treatment Plans

Surgical removal of the tumor is necessary. In addition to the tumor, your veterinarian will remove tissue from around the tumor and affected mammary gland.

Chemotherapy is often used to prevent the cancer from returning. Even with chemo, 65 percent of these tumors return.