What are the common symptoms of mastitis in dogs and cats?

Common symptoms include mammary redness and swelling, pain on touch, abnormal discharge, and often fever or reduced appetite. If symptoms are severe or rapidly worsening, consult your vet promptly.

How can I observe my pet at home and prepare for the vet?

Record the onset time, appetite, and water intake; take photos or videos of the mammary glands and any discharge; note whether the young are nursing — bring all of this information to your vet appointment.

What tests will the vet perform at the clinic?

Common tests include a physical examination, mammary discharge smear, bacterial culture, blood count, and biochemistry panel. Ultrasound or X-ray may be used if needed to assess abscesses or deeper tissue involvement. Treatment is determined from these findings.

When should I take my pet to an emergency vet?

If your pet has a persistent high fever, extreme lethargy, heavy purulent mammary discharge, or is dehydrated and unable to nurse, seek emergency veterinary care immediately.

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

Mastitis in Dogs & Cats: Symptoms, Diagnosis & Care Guide [2025]

Mastitis is a common condition in nursing female dogs and cats, causing mammary gland swelling, redness, heat, and pain. It requires antibiotic treatment and may need surgical drainage in severe cases.

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap Editorial Team

Sources: WSAVA, ISFM, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate veterinary care (emergency)

•Persistent high fever with clearly weakened spirits
•Severe swelling of the mammary glands accompanied by purulent discharge
•Marked dehydration with refusal to eat or inability to nurse

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

•Red, swollen mammary glands that are clearly uncomfortable when touched
•Discharge becoming cloudy or the appearance of bloody discharge
•Abnormal suckling by the young or the mother refusing to nurse

01What symptoms indicate a problem?

Mastitis in dogs and cats can cause both systemic and local mammary symptoms, often accompanied by behavioral or nursing changes.

Lethargy, drowsiness, or a noticeable drop in energy
Reduced appetite or the mother refusing to nurse her young
Fever and elevated body temperature, possibly with chills
Mammary gland redness, swelling, pain, or firmness on touch
Nipple discharge that becomes cloudy, blood-tinged, or purulent

Seek emergency care immediately if you notice the following symptoms:

⚠️ Persistent high fever with significant deterioration in alertness
⚠️ Severe mammary swelling with purulent discharge
⚠️ Evident dehydration with refusal to eat or inability to nurse

02How to assess the situation at home? Key observations and emergency criteria

Observing and recording key information at home helps your vet assess the condition and make decisions quickly.

Note the onset time and the sequence and progression of symptoms
Track daily changes in appetite, water intake, and activity level
Take photos or videos of mammary swelling, redness, and discharge
Monitor whether the young are nursing and if the mother is rejecting them
Observe urination and defecation, and watch for signs of dehydration
If symptoms worsen, arrange a veterinary consultation as soon as possible

03How will the vet diagnose this? Common examinations and tests

The vet will perform a visual inspection and physical exam at the clinic, ordering lab tests and imaging when needed to clarify the diagnosis.

Physical examination

palpating the mammary glands to assess pain, lumps, and local heat

Mammary cytology

smear of discharge to examine inflammatory cells and purulent material

Bacterial culture and sensitivity testing

identifying the causative organism and guiding antibiotic choice

Blood count and biochemistry panel

assessing the systemic infection response and organ function

Ultrasound or X-ray

evaluating for abscess formation or deep tissue involvement

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

Treatment is tailored to the examination findings and may include medication, surgical intervention, follow-up visits, and home care guidance.

The vet will select an appropriate antibiotic and pain management protocol based on test results
If an abscess or necrotic tissue is found, drainage or surgical intervention may be required
Home care essentials: keep the mammary area clean and warm, and ensure adequate hydration
Attend follow-up appointments as directed to review culture results and monitor mammary or wound healing
If symptoms recur or worsen, consider arranging a specialist referral for further evaluation

05What should you prepare before the vet visit? Key information to help your vet quickly identify the cause

Bring a record of when symptoms began and how they have changed day by day

Note recent appetite, water intake, bowel and bladder activity, and energy level

Prepare photos or videos of mammary swelling and discharge for the vet's reference

Bring records of recent medications, vaccination history, and any past medical conditions

If there is any discharge, collect it in a clean container and bring it to the clinic

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.