HEART MURMURS IN CATS

What they mean and why do we need to monitor them?

Being told your pet has a heart murmur can sound worrying, but many pets with heart murmurs feel completely well and live happy, active lives. In fact, heart murmurs are a fairly common finding during routine check-ups. A murmur simply tells us that blood flow through the heart sounds a little different than usual — it does not automatically mean heart failure or that treatment is urgently needed.

Our goal in investigating heart murmurs is to gather more information, so we can make the best decisions for your pet’s long-term health and comfort.

What is a heart murmur?

A heart murmur is an extra sound your veterinarian hears when listening to your pet’s chest with a stethoscope.

Instead of the normal “lub-dub” heartbeat, a murmur sounds like a soft whoosh or swish caused by turbulent blood flow inside the heart or nearby blood vessels.

A murmur is not a diagnosis on its own — it’s a clue that tells us we should look more closely at how your pet’s heart is working.

What causes heart murmurs?

Heart murmurs can occur for several reasons, including:

Changes in heart valves (they may not open or close properly)
Heart muscle disease (the heart walls may be too thick or too weak)
Abnormal blood flow within the heart
Congenital (present from birth) heart defects
Conditions outside the heart, such as anaemia or fever.

How do vets grade heart murmurs?

We grade heart murmurs based on how loud they are, using a scale from Grade 1 to Grade 6.

A higher grade does not always mean more severe disease, but louder murmurs are more likely to be associated with structural heart changes, which can often benefit from medication.

Some murmurs are mild and never cause problems, while others are linked to significant heart disease. The challenge is that we can’t tell the exact cause just by listening, so may recommend an ultrasound of your pet’s heart (echocardiogram).

Why do we recommend a heart ultrasound (echocardiogram)?

A heart ultrasound, also called an echocardiogram, allows us to:

See the heart valves and chambers to hopefully identify the source of a heart murmur.
Measure heart muscle thickness and size of your pet’s heart chambers, checking for evidence of dilation.
Decide whether treatment is needed now or just monitoring

It is non-invasive, painless, and does not involve any radiation. In most cases, the scan can be done conscious but in more anxious pets we may recommend a mild sedation to relax them and ensure we get accurate measurements.

When do we recommend an ultrasound?

In cats, We usually recommend an ultrasound for any heart murmur, even if very quiet.
This helps us detect heart disease early, often before symptoms appear.

What usually happens when my cat comes for an ultrasound of their heart?

Your cat will usually just need to stay with us for a morning or afternoon (and get plenty of cuddles from our team throughout!) The vast majority of scans can be done without sedation but we sometimes need to give a mild sedation to ensure we get accurate measurements and make sure we’re not missing anything. Our vets will always discuss this with you if they feel your cat needs a little sedation.

The vet will be able to discuss the results of the scan on the same day and make a plan for your cat’s heart that suits your lifestyle and budget. So you can go home with the peace of mind that you’ve have done everything to keep your cat’s heart pumping and throat purring for as long as possible.

Watch the video below to see Betty’s heart scan journey with us (though Betty is a dog, your cat will have a very similar day):

Why early detection matters?

Many pets with heart disease:

Feel completely normal at first
Have no cough, breathing issues, or exercise intolerance

Finding heart disease early allows us to:

Start treatment at the right time
Monitor progression
Reduce the risk of heart failure or sudden complications

By grading murmurs and recommending ultrasound scans at appropriate stages, we aim to support your pet’s heart health and quality of life — while avoiding unnecessary tests when they aren’t needed.

If you would like any further information please do get in touch with one of the team, who’d be more than happy to help.

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