Are mammary tumours common in cats?

Mammary tumours do occur in adult female cats, with intact (unspayed) females at higher risk. If you notice a mammary nodule, have it evaluated by a vet and arrange appropriate tests.

How does the vet confirm a mammary tumour diagnosis?

Your vet will begin with a physical exam and cytology, then proceed to tissue biopsy or imaging (X-ray, ultrasound, CT) as needed. The definitive diagnosis is based on the histopathology report.

What treatment options are available?

Surgical excision is the primary treatment. Chemotherapy or other adjuvant therapies may be discussed based on histopathology and staging. Regular post-operative check-ups and imaging follow-up are required.

How is the prognosis assessed after surgery?

Prognosis varies depending on whether the tumour is benign or malignant, its size, and whether metastasis has occurred. Early detection and complete excision are generally favourable. Discuss your cat's individual risk and follow-up plan with your vet.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Cat Mammary Tumours: Lumps, Diagnosis & Treatment Guide [2025]

Around 85–90% of feline mammary tumours are malignant. Wide surgical excision is recommended, and early desexing significantly reduces the risk.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: ISFM, AVMA

When to See a Vet

Seek emergency care immediately

•Persistent rapid breathing or wheezing
•Ulcerated mammary gland with heavy bloody discharge
•Sudden lethargy, stupor, or unresponsiveness

Schedule a clinic visit soon (within 24–72 hours)

•A mammary lump growing rapidly within a short period
•Noticeable change in nodule mobility or fixation on palpation
•Significant loss of appetite with continued weight loss

01What symptoms indicate something is wrong?

Mammary tumours typically cause a localised lump in the breast tissue and may be accompanied by systemic changes in appetite, activity, or breathing.

A hard lump or noticeable swelling in the mammary glands, which may change in size or texture
A palpable nodule that may feel mobile or fixed in place
Lethargy, reduced energy levels, and less interest in jumping or playing
Decreased appetite or gradual weight loss
Skin breakdown, ulceration, or discharge from the mammary area
Rapid or laboured breathing if pulmonary metastasis has occurred

Seek emergency care immediately if you notice the following symptoms:

⚠️ Difficulty breathing or pronounced respiratory distress requires immediate assessment
⚠️ Mammary ulceration with heavy bleeding warrants urgent veterinary attention
⚠️ Sudden collapse or unresponsiveness is a medical emergency

02How can I assess the situation at home? Key observations and when to go to emergency

Keeping a home record of changes helps your vet quickly understand the condition and plan the appropriate tests.

Note when the lump was first discovered, its size, and how quickly it has changed
Monitor and document trends in appetite and water intake
Take dated close-up photos of the lump daily for comparison
Record short videos of your cat at rest and while moving to show energy and gait
Track urination, defecation frequency, and body weight over time
Organise your records and photos to bring to the oncology specialist or veterinary hospital

03How will the vet diagnose this? Common diagnostic tests

Your vet will use physical examination and imaging to assess tumour extent, possible metastasis, and surgical risk.

Physical examination

palpation of the mammary chain and assessment of regional lymph node size

Blood tests

evaluation of overall health and anaesthetic risk

Cytology (fine-needle aspiration or impression smear) for preliminary cell morphology assessment

Ultrasound

assessment of peri-mammary tissue and possible abdominal metastasis

Radiography

chest X-rays to check for pulmonary metastasis or other thoracic abnormalities

Advanced imaging (e.g. CT scan) for more precise staging and surgical planning

Consider referral to a veterinary oncology hospital equipped for complete imaging and surgery

04What treatment and aftercare are needed? Medications, diet, and home care guide

Treatment must be tailored individually; surgery is usually the primary approach, with adjuvant therapy discussed based on histopathology results. Regular follow-up is essential.

Surgical excision: the extent of resection is determined by tumour size and location
Chemotherapy or other adjuvant therapies: considered based on histopathology and staging
Pain management and anti-infective treatment to improve recovery quality
Regular post-operative check-ups with repeat imaging and blood tests
Wound care and restricted activity — prevent licking or vigorous exercise
Discuss long-term monitoring and management of potential complications with your oncologist

05What should I prepare before the vet visit? Key steps to help your vet work efficiently

Write down when symptoms first appeared and any subsequent changes

Bring a record of appetite, water intake, and litter box habits from the past few days

List all current medications, supplements, and vaccination records

Have close-up photos and activity videos of the lump ready on your phone for the vet to review

Bring any previous test reports or imaging files if available

Book an appointment in advance at a veterinary hospital with oncology capabilities

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.

Related Symptoms (You May Also Be Looking For)

Loss of appetite

Difficulty breathing

Tissue swelling

Skin redness

Limping

Decreased activity