Heart Murmurs

Sometimes during routine consultations, your vet may diagnose a heart murmur. This is often unexpected and stressful to hear – the below will help provide a clear understanding of what this might mean for you and your loved pet.

What is the function of the heart?

First, let’s go back to basics – the heart is essentially a one way pump with 4 chambers. The heart should push blood forwards – the right side of the heart pushes blood into the lungs (to oxygenate the blood) and the left side of the heart pushes oxygenated blood into the body.

In between the chambers of the heart are valves to seal the chambers when the heart contracts. When we hear the “heart beat” we are actually hearing the valves snapping closed.

In horses we can hear all 4 valves, but in smaller animals, it is difficult to distinguish the 4 separate valves by listening alone.

What is a heart murmur?

When we auscultate (listen with a stethoscope) the heart and we hear a whooshing sound showing blood turbulence in the heart, this is usually sign that a valve is leaking. This can be because the heart has enlarged (and the valves are now too small) or, more commonly, that the valves have deteriorated.

We grade murmurs according to their position in the chest (which gives us clues about which valve/s may be leaking) and their loudness (graded from a 0 – no murmur to a maximum level of 6)

Many animals, particularly older dogs, can develop mild murmurs that do not cause them any health issues. Importantly, the loudness of the murmur does not always correlate to clinical disease.

Some murmurs – particularly in cats – can be a result of other disease processes such as Hyperthyroidism and we may recommend a blood test to further assess.

How can we assess the heart function?

The best way to further assess the heart is by Echocardiography – an ultrasound of the heart. This is performed by a specialist, and we are happy to provide a referral as necessary. The scan detects structural changes in the heart, allowing us to start medications at the most appropriate time for individual animals.

We may also ask that you monitor Resting Respiratory Rate at home (breathing rate at rest should be less than 25-30 breaths per minute) as this can be an indicator of more advanced heart disease.

Heart murmurs can remain stable for many years, but some animals go on to develop Congestive Heart Failure. We have medications available that can slow the progression of the disease and deliver a very good quality of life, sometimes for years.