Heart murmurs in dogs – signs and what to do

Updated 2026-09-30 · 1 sources

Based on: PDSA

Book a vet visit

Book a vet appointment if you think your dog has this – a vet needs to confirm it and plan the treatment. A heart murmur is a whooshing noise caused by abnormal blood flow inside your dog's heart.

What to do now

What you can do now

Contact your vet.
Note when it started, how often it happens and what else you see.
Take a photo or short video to show the vet.
Let your dog rest somewhere calm.
Keep fresh water available.

Don't

Do not give any human medicine.
Do not wait if it gets worse.

What it is

A heart murmur is a whooshing noise caused by abnormal blood flow inside the heart.^[1] Some murmurs, including innocent flow murmurs, are harmless, while heart disease, anaemia and general illness, and pregnancy can cause heart murmurs in dogs.^[1] Signs that can occur with heart murmurs include coughing, low energy, weakness, breathing trouble, collapse, a swollen abdomen and pale gums.^[1]

Signs

Coughing
Low energy
Weakness
Trouble breathing, fast breathing or breathlessness
Collapse
Swollen abdomen
Pale gums
Breathlessness and mouth breathing
Weight loss
Changes in appetite

Causes and risk factors

Heart disease
Anaemia and general illness
Pregnancy
Innocent flow murmurs

How a vet finds out

Physical examination
Blood tests
X-rays
Ultrasound
ECG
Echocardiogram

How vets treat it

Medication

What the experts say

“Overview. A heart murmur is a whooshing noise caused by abnormal blood flow inside the heart. There are a few different conditions that can cause heart murmurs in dogs. Not all heart murmurs are problematic; some (such as ‘innocent flow murmurs’) are harmless.”
— PDSA [1]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

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Common questions

What is a heart murmur?

It is a whooshing noise caused by abnormal blood flow inside the heart.^[1]

Are all heart murmurs a problem?

No. Some, such as innocent flow murmurs, are harmless.^[1]

What signs can a dog with a heart murmur have?

Signs can include coughing, low energy, weakness, trouble breathing, collapse, a swollen abdomen and pale gums.^[1]

Sources

PDSA

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages

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