Ginger cat at the vet

Cat breast cancer is more commonly known as mammary cancer.

© Shutterstock

Everything you need to know about cat breast cancer

By Dawn Parrish Content Writer

Updated on the

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.

Cat breast cancer is more commonly known as mammary cancer and is a serious and aggressive form of cancer. So, if you find a lump near one of your cat’s nipples, it’s a good idea to get it checked out by a vet swiftly.

Here we will learn all about mammary cancer in cats, and what to look out for.

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 more mammary glands and is often a malignant adenocarcinoma tumour, however, 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 carry a varied, and often poor prognosis.

 Female cat mammary glands © Shutterstock

A female cat has four 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, as these drain the lymph from the mammary glands. 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 
  • 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
 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 influence the risk of developing mammary cancer. Oestrogen medications given to female cats can also 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 and a urinalysis will all be taken to assess your cat’s overall health. Other medical tests may include an ultrasound, to ensure cancer hasn’t spread to other organs in your cat’s body. Fine needle biopsy or surgery of the affected glands and lymph nodes could be advised to examine the tissue sample for malignancy.

Are mammary tumours in cats painful?

Cats are difficult to assess for pain as they are generally stoic creatures. However, cancerous tumours are considered to be painful in humans. So, what does cancer feel like on a cat? We can assume that they are painful for cats too. This is even more reason to ensure your cat receives at least palliative treatment to ensure she is comfortable, and not be left without treatment even if the prognosis is hopeless.

Treatment options for cat breast cancer

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. Chemotherapy is often used in addition to surgery, or when the cancer has progressed too much for surgery


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. This means not only the mammary gland will be removed, but the whole strip of mammary glands on one or both sides.


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, the type of tumour your cat has 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 non-aggressive tumour smaller than 2cm – survival rate up to three years
  • Tumours 2-3cm in size – survival up to two years
  • Larger than 3 cm or aggressive form of tumour – the cat may live up to six months

Any cat’s survival chances are greatly increased if the owner takes him to the vet as soon as any breast lumps are noticed.

Can cats survive breast cancer?

By definition cats can survive breast cancer, however it is always a concern that it might go into remission. However, for the tumours with longer survival rates, such as non-aggressive small tumours, it’s possible that the end cause of death will be unrelated to the mammary cancer.

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 frequently. Certainly, if you discover anything suspicious, take 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.

Reviewed by Dr Jo de Klerk, BVetMed (Hons) MScTAH MRCVS 
More advice on...

What did you think of this advice article?

Thanks for your feedback !

Thanks for your feedback !

Leave a comment
Connect to comment
Want to share this article?