What’s That Sound? A Hearty Rundown on Heart Murmurs

Hearts are miraculous little things! We’ve all got one, people and pets alike, and they all work hard to keep our blood pumping and our bodies healthy. We’re all familiar with the steady, rhythmic, comforting sound of a heart beat, but what about a heart murmur? What is this unusual sound, what causes it, and is it something to be concerned about? Let’s tackle these cardiac questions one at a time!

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What is a heart murmur?
​A heart murmur describes a type of abnormal sound that may be heard when listening to a heartbeat. A normal, healthy heartbeat has two distinct parts (ba-bump, ba-bump, ba-bump), which you hear as the heart contracts and expands to circulate blood. A heart murmur is an additional sound, typically heard in between these two parts (ba-woosh-bump, ba-woosh-bump).
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In a healthy heart, blood flows in a motion known as laminar flow- Have you ever held a spoon upside down under the sink, and watched as the water runs off in a curtain so smooth, it looks like it’s not moving at all? This is laminar flow, and it is the opposite of turbulent flow, where the water is splashing and spraying every which way. Turbulent flow is louder, in both your sink and your heart, so turbulent blood flow produces a heart murmur. Heart murmurs are graded on a scale of I - VI, with a Grade I being the most mild and a Grade VI being the most severe.

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What causes a heart murmur?
A heart murmur can occur any time the regular flow of blood is interrupted, which can happen for a number of reasons.

​Dogs, cats, and humans all have similarly structured hearts: four distinct chambers, separated by valves meant to keep blood flowing in a single direction. A heart murmur is often caused by a structural issue, such as a leaky valve, an irregularly-sized blood vessel, or a hole between two chambers. These structural defects, like heart murmurs themselves, can be congenital or acquired- congenital meaning they’ve been there since birth, and acquired meaning they appeared later in life. 
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​It’s not always about the structure of the heart, though. Heart murmurs can result from a number of other causes including fever, infection, obesity, pregnancy, or low levels of protein or red blood cells. Temporary heart murmurs are also common in growing puppies, often appearing by six weeks and resolving by five months.

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Is a heart murmur serious?
​Heart murmurs are a symptom rather than a disease, and as such the severity can depend heavily on the underlying cause. As mentioned above, some heart murmurs are benign and resolve with time, while others are an indication of heart disease or other more serious concerns. If treatment is indicated, it is to treat any underlying disease rather than the heart murmur itself.

​Monitoring the progression of a heart murmur is important, and to this end your veterinarian may recommend annual or semi-annual echocardiograms (a non-sedated and non-invasive procedure that can produce high-quality images of the heart), alongside blood work or other lab tests. Based on these results, your veterinarian may recommend treatments including cardiac medication, prescription diets, or surgical correction.

​While the prognosis of a pet diagnosed with a heart murmur can vary greatly depending on the severity and underlying cause, early detection will always give a pet the best chance at a long, comfortable life.

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Should I be very worried about my pet now?
It’s hard to talk about these things without them feeling scary. Fortunately, if your pet is currently happy and healthy, there’s no reason to panic! Annual checkups, as well as sick visits whenever something doesn’t feel right, allow your veterinarian to listen to your pet’s heart and catch any changes in their health early.  Weight also plays an important role in preventing and managing heart disease, so talk to your veterinarian about whether your pet is at a healthy weight and, if not, what steps you can take to get them there.

​If your pet exhibits abdominal swelling, difficulties with breathing or sleeping, rear limb weakness, or bouts of fainting, schedule an appointment promptly, as these can all be signs of heart disease.
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​Got questions we didn’t answer here? Or maybe it’s time to book a sick or well visit? Whatever the reason, drop us a line! We’re always happy to chat, answer any questions you may have, and schedule a visit if necessary.

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