Mammary tumours in cats
Also known as Breast cancer in female cats, Mammary carcinoma.
In female cats, the great majority of mammary tumours are malignant. Early spaying greatly reduces the risk.
Any lump in a female cat’s mammary glands warrants a vet visit within the week.
- System
- Tumours
- Is it urgent?
- Not usually
- Spreads to other cats
- No
- Spreads to people
- No
- Typical cost in Spain
- Mastectomy, €800–2,500.
Symptoms
- Hard lumps in the mammary glands
- Ulcers or discharge from a nipple
- Enlarged lymph nodes in the groin
- Coughing if it has spread to the lungs
Causes
Sex hormones: the risk is higher in unspayed females and in those that have been given contraceptives to stop heat.
How it is diagnosed
Examination, chest X-rays and biopsy.
Treatment
Removal of the whole mammary chain, sometimes both chains, and chemotherapy in some cases.
No doses, on purpose: any medicine must be prescribed by your vet for your cat.
Prognosis
It depends on size: tumours under 2 cm removed early have a much better outlook.
Prevention
Spay between 6 months and 1 year of age, and do not use pills to stop heat.
Breeds at higher risk
It is described more often in these breeds. That does not mean all of their cats will have it, nor that a moggy is free of it.
Frequently asked questions
What causes mammary tumours?
Sex hormones: the risk is higher in unspayed females and in those that have been given contraceptives to stop heat.
Can mammary tumours be cured?
It depends on size: tumours under 2 cm removed early have a much better outlook. Removal of the whole mammary chain, sometimes both chains, and chemotherapy in some cases.
How much does it cost to treat mammary tumours?
As a guide for Spain in 2026: Mastectomy, €800–2,500. Prices vary a lot between clinics and cities, and out-of-hours emergencies cost more.
Which breeds are most at risk?
It is described more often in Siamese and Oriental Shorthair. That does not mean every cat of those breeds will have it, nor that a moggy is free of it.
More in tumours
Educational content from Michipedia. It does not replace diagnosis or treatment by a vet: if you have any doubt about your cat's health, ask. Costs are a guide for Spain in 2026.