Heart Murmur

By Dr. Karen Burgess

What is a heart murmur?
The heart is a muscular organ that contains four separate blood holding chambers. The heart muscle functions to push or pump blood held in these chambers through the body’s blood vessels. Between the four chambers of the heart or valves that help compartmentalize the blood within the heart. When a heart murmur is heard by your doctor via a stethoscope it is actually the sound of blood flowing inappropriately through what should be a tightly sealed valve. If the heart chambers are rooms and the valves are doors, this would be similar to wind rushing through a partially closed door. There are six grades that qualify how loud a heart murmur sounds with grade one being the quietest.

What is the significance of a heart murmur?
A heart murmur alone is only a symptom. It may be innocent, meaning of no harm to the patient, or an indicator of extensive heart disease. Neither presence of nor the grade of a heart murmur are reliable indicators of whether relative heart disease is present in a pet. What it signals is that more information should be obtained to ensure overall heart health.

What tests are indicated when a heart murmur is diagnosed?
In some cases the first recommendation may be to simply reauscult the heart in several weeks. Some medical conditions that may be temporary (ex. change in hydration status, fever, infection) can lead to transient murmurs that will self-resolve. Further evaluation of the heart typically involves imaging. Radiographs or x-rays of the chest can help define the size and shape of the heart, the density of the lungs, and look for other anatomical issues. Radiographs do not determine how the heart is functioning. An ultrasound or echocardiogram of the heart allows direct visualization of the heart size, shape, and real time views of the valves and heart muscle. While a more expensive test, and echo is the gold standard for evaluating overall heart health. Laboratory tests, EKG (evaluates the electrical impulses that cause the heart to contract), and blood pressure measurement are also typical diagnostics when evaluating a heart murmur.

a heart murmur be harmless?
Yes, in some cases a heart murmur is innocent. This means that there is no corresponding or detectable heart disease. These are most commonly seen in young puppies less than fifteen weeks old. It is important to ensure these murmurs resolve as puppies can also be born with congenital heart defects which are far more problematic.

What if my pet is found to have heart disease?
There are a variety of specific diseases and treatments that affect the heart. Without an echocardiogram it is impossible to treat a pet for a specific problem and therefore improve chances of success. Treatment may involve medication, diet change, or in some rare cases surgery.