Everything you need to know about cat breast cancer

Ginger cat at the vet advice
© Shutterstock

Cat breast cancer is the third most frequently diagnosed feline cancer. This disease normally affects older female cats that haven’t been spayed but male cats are also at risk.

By Dawn Parrish

Updated on the 06/12/2019, 15:22

What is cat breast cancer?

Feline breast cancer is an alarming diagnosis for any pet owners. Many owners won’t even know their cat has a problem unless you pet your cat frequently and feel a mammary lump. Perhaps your cat is chewing or licking at the area affected. Likewise, some tumours are only discovered during routine medical examinations.

Feline breast cancer has many similarities to human breast cancer. It will develop in one or both breasts as a malignant adenocarcinoma tumour. There are other types of cat breast cancer – sarcomas, duct papilloma and adenomas. Both male and female cats are at risk. Survival rates, even after treatment with chemotherapy, radiation and surgery aren’t great.

cat breast cancer
 Female cat mammary glands ©Shutterstock

A female cat has 4 mammary glands on each side of the abdomen, which produce milk for kittens. Lymph nodes in the groin and armpit are most susceptible to cancer. In felines, 85% of breast cancer tumours are found to be malignant.

Likelihood of developing cat breast cancer

First of all, it’s important to note that the age at which you have your female kitten spayed can play a role in cancer prevention. As a result of neutering a female cat before 6 months of age, 91% have a reduced risk of a tumour developing. There is an 86% reduction if the kitten is spayed between 6 and 12 months old. Likewise, for cats between 1-2 years, a, 11% reduction in cancer diagnosis is reported. However, for cats over the age of 2 years, the risk of developing mammary cancer in cats is not reduced at all. Evidence points to a higher reported occurrence in both Siamese and domestic short-haired cats.

Symptoms of breast cancer in cats

By the time the breast cancer is diagnosed, the symptoms are usually well-advanced. Symptoms to look out for include:

  • Swelling of the mammary glands or breast tissue – possible infected areas
  • Ulcers and sores on the skins surrounding the mammary glands
  • Discharge from the nipple area, either milky, bloody or clear
  • Obvious tumours attached to the skin and muscle near the abdomen area
  •  Fever, pain, weakness and weight loss
cat breast cancer
 Symptoms of cat breast cancer ©Shutterstock

Causes of cat breast cancer

There appear to be several influencing factors why feline mammary cancer develops. Not having the cat spayed at a young age or allowing the cat to give birth to kittens in several litters before spaying. Oestrogen medications given to female cats can trigger the disease. As previously mentioned, Oriental, Persian and Siamese breeds are more prone to this condition.

Diagnosis of feline mammary cancer

Because diagnostic procedures depend on the location and size of the tumours, a medical examination is needed. Blood work, urine analysis and chemistry profiles will all be taken. Other medical tests include ultrasound, to ensure cancer hasn’t spread to other organs in the cat’s body. Fine needle biopsy or surgery could be advised to examine the tissue sample for malignancy.

Treatment options for cat breast cancer

After an initial medical consultation when a physical examination will take place, the vet will touch and sense a tumour or mass. The lymph nodes will also be examined. Following diagnosis, the following treatments could be an option:


This form of chemical treatment is an option to treat feline mammary cancer. Clinical trials into the use of various drugs to determine which combinations and doses of medication are ongoing.


cat breast cancer
Cat prepared for breast cancer surgery ©Shutterstock

The main aim when going the surgery route is to remove the mass. In the majority of cases, either a unilateral or bilateral mastectomy will be needed. There are associated risks such as infection and death from the anaesthetic.


This type of radiation treatment is not usually suggested as there is no reported evidence that it improves a cat’s quality of life.

Prognosis after treatment for cat breast cancer

Certainly, the prospects of how long the cat will live after cancer depend on many factors. The extent and recuperation from surgery, the size of a tumour and your cat’s health situation will all have a bearing. However, as a result of medical findings in recent years, following diagnosis and treatment for cat cancer, these assumptions can be made:

A Tumour smaller than 2cm – survival rate up to 3 years
Tumours 2-3cm in size – survival up to 2 years
Larger than 3 cm – the cat may live up to 6 months

Similarly, if early diagnosis and treatment for small tumours occur, the cat might live for up to 3 years. Any cat’s survival chances are greatly increased if the owner takes him to the vet as soon as any breast lumps are noticed. Statistics from The Ohio State University - Veterinary Medical Centre

Probably the most important factor to prevent your cat from getting breast cancer is to have her spayed as a kitten. If you decide not to go this route, inspect her breast area for sores or lumps quite frequently. Certainly, if you discover anything suspicious, taker her for a medical examination. It may not be cancer, but you have nothing to lose except the cost of an appointment. The sooner cat breast cancer is discovered, the more chance for your cat’s long-term survival.