What are the early signs of myxomatous mitral valve disease?

Early signs may include panting after activity or reduced stamina, and you may also notice coughing or obvious breathing effort during sleep. If you see these changes, record them and speak with your vet.

What tests do vets usually use to confirm the condition?

Common tests include a physical examination with auscultation, chest X-rays, cardiac ultrasound, and blood tests. Ultrasound helps assess the valve and heart function. Further imaging or specialist assessment may be recommended if needed.

How can I help monitor the condition at home?

You can record body weight, appetite, activity level, and breathing rate each day, and take videos of coughing or panting. This information helps your vet assess changes in the condition and response to treatment.

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

Myxomatous Mitral Valve Disease in Dogs and Cats: Breathing Difficulty, Ultrasound & Home Care [2025]

Myxomatous mitral valve disease is the most common heart disease in small-breed dogs. Valve degeneration causes backflow and may require long-term medication to control heart failure.

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap Editorial Team

Sources: ACVIM, AAHA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek emergency care immediately

•Continuous open-mouth breathing or flared nostrils
•Noticeably blue or pale lips or gums
•Sudden collapse, loss of consciousness, or unresponsiveness

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

•Persistently elevated resting respiratory rate
•Significantly reduced exercise tolerance and easy fatigue
•Recurring cough or increasing frequency of nighttime coughing

01What Symptoms Suggest Something Is Wrong?

This condition often causes clinical signs and warning symptoms related to impaired heart valve function. Early signs may be subtle, so watch for changes in activity level and breathing.

Faster breathing, obvious panting while asleep, or laboured breathing
Reduced exercise tolerance, tiring easily, or reluctance to move
A faster heartbeat or occasional irregular rhythm that you may be able to feel
A swollen abdomen from fluid build-up, or swelling in the lower limbs or hips
Low energy, reduced appetite, or changes in body weight

Seek emergency care immediately if you notice the following symptoms:

⚠️ Rapid breathing with open-mouth breathing or flaring nostrils
⚠️ Lips or gums that look clearly blue-purple or pale
⚠️ Sudden collapse or complete unresponsiveness

02How Can I Assess Abnormal Signs at Home? Key Monitoring Points and Emergency Criteria

Specific observations recorded at home can help your vet assess the condition and monitor treatment response. Photos or videos are especially useful.

Record your pet's breathing rate at rest and after activity, and note whether breathing looks effortful
Take short videos at rest and after activity, showing both breathing and movement
Measure and record body weight and appetite changes every day
Note any coughing, vomiting, toileting changes, and how often they occur
Write down when episodes happen, how often they occur, and all current medicines and supplements
If anything seems abnormal, arrange an appointment early with a clinic that can perform cardiac ultrasound

03How Will the Vet Diagnose It? Common Tests

At the clinic, your vet will combine the medical history and test results to assess heart function and decide whether further treatment is needed.

Physical examination

listening for a heart murmur and assessing breathing and overall condition

Chest X-rays

assessing heart size and checking whether there is fluid or oedema in the lungs

Cardiac ultrasound

detailed assessment of valve function and changes in heart structure

Complete blood count and biochemistry

checking for other internal medicine problems or complications

Blood pressure and heart rhythm monitoring

short-term checks for hypertension or arrhythmias

Further imaging, such as CT, or referral to a specialist if needed

04How Is It Treated and Managed After Diagnosis? Medication, Diet Changes, and Care Guide

Treatment aims to improve symptoms, slow progression, and support quality of life. Long-term follow-up and consistent home monitoring are important.

Medication should be given under veterinary guidance, with regular rechecks and dose adjustments
Continue monitoring breathing and day-to-day activity levels at home
If signs are severe, short-term oxygen therapy or hospital monitoring may be needed
Schedule regular cardiac ultrasounds and blood tests to track the condition
Use diet control and weight management, adjusting food and activity as advised by your vet
If symptoms worsen, return to your vet immediately or seek care at a cardiology referral hospital

05What Should I Prepare Before Seeing the Vet? Key Details That Help Identify the Cause Quickly

Record when symptoms started, how they have changed, and how often episodes occur

Bring short videos showing abnormal breathing, coughing, or activity

List all current medicines and supplements, including names and dosing frequency

Record changes in appetite, water intake, and toileting frequency

Bring any previous imaging or test reports, or keep digital copies ready

Call ahead to book a cardiology appointment and describe the main symptoms

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.