I know what it feels like to be a new pawparent. There’s a high in the joy and excitement of a new furbaby. You can’t believe something this adorable can be real! And then the vet tells you your furbaby has a heart murmur.

Your reaction may run along the lines of: “That sounds terrifying! What’s a heart murmur? Is it fixable? Is my furbaby going to fall apart?”

BUT this is also when we tell you heart murmurs in puppies can be normal although it could be a symptom of a condition which needs to be addressed.

What is a Heart Murmur?

When vets are listening to the heart through a stethoscope, we can hear the rhythmical lub-dub. When there is any turbulence of blood flow, the lub-dub is replaced by a swoosh noise – swoosh-dub, swoosh-swoosh, etc. This is what we call a heart murmur.

A heart murmur is not a name for a disease, but a name for what we hear – and heart murmurs can be caused by many different conditions.

What Causes Heart Murmurs?

Blood flow can become turbulent with changes in blood thickness has changed, blood rushing past abnormal structures, or blood rushing too quickly past a normal structure (in cases of excitement and exercise, for example).

Heart Murmurs in a Young Furbabies

A soft “innocent” murmur in puppies before 14 weeks of age can be quite common. In one study, one in ten puppies were found to have a soft murmur! Puppies have a lower red blood cell concentrating – leading to altered blood viscosity. For that reason, animals with anaemia are also known to have a soft heart murmur.

There are, of course, other causes of murmur in puppies and kittens that are less innocent. They can be born with structural defects of the heart: usually narrowed vessels or unclosed holes in the heart.

Depending on the severity, these conditions need to be addressed for the puppies to have a good quality of life. In severe cases, puppies and kittens with the condition do not make it past the age of one if the condition goes untreated.

Now What?

Depending on what the veterinarian can hear, they are most likely to recommend you one of the two following options: 1) to monitor and recheck to assess the heart murmur again in a few weeks. Remember, an innocent heart murmur is a pretty common finding and they are self-limiting. 2) Further investigation of the heart murmur.

Further Investigation

Referral to a cardiologist or an ultrasonographer for assessment with an echocardiogram is the most reliable way to characterise a congenital heart defect. While listening with a stethoscope is a pretty good way to first catch the disease, figuring out where it is and how much trouble it’s causing is best done with an echocardiogram.


Dogs with innocent heart murmurs do not require treatment – and these heart murmurs tend to disappear in a couple of months. However, dogs with congenital heart disease require surgical intervention by a specialist. Treatment differs depending on each condition – that’s why an accurate diagnosis is so important!

In Summary

Prognosis of the innocent heart murmur is excellent. With a surgical treatment, the prognosis for congenital heart disease is fairly good – about 80%.

A heart murmur can be big news for a new pawparent. But earlier the diagnosis is made, the better the prognosis for the furbaby! Your veterinarian is there to support you through this!

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