What Causes Heart Murmurs in Cats and Dogs?


My indoor cat MidgeyGirl was diagnosed three years ago with a heart murmur, she’s six now. Should I be concerned? I haven’t had her checked in some time, since I’ve moved to another state. Does this murmur ever correct itself, is there medication for this? Thank you!

Stuart, FL

A heart murmur is a description of how the heart sounds when a veterinarian listens to it. The presence or absence of a heart murmur does not always correlate with the presence or absence of heart disease.

A heart murmur signifies turbulent flow of blood through the heart. Under normal circumstances blood flows through the heart smoothly and soundlessly. In animals with heart murmurs the blood does not flow as smoothly, and this causes a shushing noise that is called a heart murmur.

Blood flowing through the heart is similar to water flowing through a hose. A kink or irregularity in the hose can lead to a shushing noise as the water flows through. Any irregularity in the structure of the heart or the flow of blood through the heart causes a similar shushing noise.

Heart murmurs come in two broad categories: non-pathological and pathological. Non-pathological heart murmurs are caused by benign hereditary or developmental anomalies and other harmless irregularities in the structure (but not the function) of the heart.

Pathological heart murmurs are caused by leaky valves, irregularities in heart muscle structure, or anatomical irregularities that compromise heart function.

Animals like MidgeyGirl that develop heart murmurs at a young age often have non-pathological murmurs. Animals that develop heart murmurs late in life most often have pathological heart conditions.

However, there is absolutely no way to tell whether a murmur is pathological or non-pathological simply by listening to it. Diagnostic tests are needed to determine whether disease exists and whether medications are necessary.

A combination of chest X-rays and ultrasound of the heart (known as echocardiography) almost always reveals whether heart pathology is present. Basic blood tests (and a special blood test called pro-BNP) also are useful.

I recommend that your vet perform these tests on MidgeyGirl. Hopefully the results will put your mind at ease.

Go to my website for more information on heart disease in pets.
Cats: http://drbarchas.com/feline_heart_disease
Dogs: http://drbarchas.com/canine_heart_disease

Photo: Lola‘s heart looks good!

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