Heart Murmurs in Pets: What Does It Mean?
Your vet detected a heart murmur. Don't panic — learn what it means, what causes it, and what happens next.
A heart murmur is an extra heart sound heard through a stethoscope — it's a 'whooshing' noise caused by turbulent blood flow. Heart murmurs are extremely common in pets and don't always indicate serious heart disease. However, they do warrant further investigation to determine the cause.
- A heart murmur is a sound, not a diagnosis
- Not all murmurs indicate serious heart disease
- Murmurs are graded 1-6 based on loudness
- Common causes: valve disease, anemia, fever, heart defects
- An echocardiogram is needed to determine the cause
- Many murmurs in young puppies are 'innocent' and resolve on their own
Understanding Murmur Grades
Murmurs are graded on a scale of 1-6: Grade 1: Barely audible, only detected in a quiet room. Grade 2: Soft but easily heard. Grade 3: Moderate. Grade 4: Loud with a palpable thrill (vibration). Grade 5: Very loud, heard with stethoscope barely touching the chest. Grade 6: Loudest possible, heard without the stethoscope touching the chest. Higher grades generally indicate more significant turbulence.
Common Causes
In older small-breed dogs: mitral valve disease (the most common cause). In older cats: hypertrophic cardiomyopathy. In puppies: innocent flow murmurs (benign, usually resolve by 4-6 months). Other causes: anemia, fever, hyperthyroidism (cats), congenital heart defects, dilated cardiomyopathy, and infections. Some medications can also cause murmurs.
What Happens Next
Your vet will likely recommend an echocardiogram (heart ultrasound) to visualize the heart and determine the cause of the murmur. This is painless and non-invasive. Chest X-rays may also be recommended to check heart size and lung condition. Blood tests (including NT-proBNP) can help assess heart disease severity. Based on results, your vet will recommend monitoring or treatment.
Living With a Murmur
Many pets with murmurs live completely normal lives for years. If the murmur is due to valve disease, regular monitoring (every 6-12 months) allows your vet to track progression and start medication at the right time. There's no need to restrict activity unless your vet specifically recommends it. Don't panic — a murmur is the beginning of a conversation, not a sentence.
- Your vet detected a murmur for the first time
- Coughing or breathing difficulty
- Exercise intolerance or lethargy
- Fainting
- Your pet's murmur has gotten louder at a follow-up visit
- You have concerns about your pet's heart health
RVC
RVC offers echocardiography, chest X-rays, and cardiac blood tests to evaluate heart murmurs. We'll determine the cause and create a monitoring or treatment plan. Call +853 6677 6611.
+853 6677 6611