Heart Murmurs and Your Pets

September 11th 2015

What is a heart murmur?

A heart consists of four chambers (atrium and ventricles) separated by valves.

Blood enters the heart through the vein into the right atrium. From there, it goes through the tricuspid valve into the right ventricle. The right ventricle pumps the blood through the pulmonary artery and semilunar valves into the lungs. From there, oxygenated blood comes back to the heart into the left atrium. It goes through the mitral valve into the left ventricle, and is pumped into the aorta and through the semilunar valves, providing the body with oxygenated blood (see Figure below).

The closing of the valves creates the heart sounds we can hear while examining your pet using a stethoscope. When valves are not fully closing, or there is a defect in one of the chambers, blood keeps flowing even when the valves are closed and creates a squirting, turbulent sound, or a murmur. There are also diseases associated with the heart muscle that can cause these murmurs.

Heart murmur symptoms in your pet

Most of the time, you'll not notice anything, but your veterinarian can identify a murmur during the annual physical exam.

Physiologically, a heart can compensate for a leak and no further symptoms are present. Over time, the heart might not be able to compensate anymore and this will result in congestive heart failure and fluid will start to build up in the lungs or in some cases in the abdomen, creating a swollen belly.

Depending on the location and severity of the leak, a variety of symptoms can be observed. Most typically, one of the first symptoms is exercise intolerance. Your dog may not be able to keep up on walks anymore or go for as long of a walk as usual. This may be accompanied by difficulty breathing, coughing and eventually fainting due to shortness of breath. In cats, these symptoms occur as well but, tend to be more subtle.

Diagnosing a heart murmer in a cat or dog

The first diagnostic step is to take a radiograph of the chest to evaluate the heart and vessel size and the lungs.

Secondly, bloodwork can be done to ensure your dog or cat’s kidney and liver are fit for long term use of medication.

Next, an ultrasound by a veterinary cardiologist can provide more detailed information about the location of the valve leak, process and stage of disease. This is usually combined with an electrocardiogram as well to evaluate the electrical activity in the heart.

Natural and medical treatments of a heart murmer

In the first situation, when only a murmur is present and your dog or cat are doing well and has no signs of congestive heart failure, generally no treatment is indicated.

Avoidance of strenuous exercise (more than your normal day-to-day activities) and regular follow-up exams by your vet are the way to go.

In the second situation, where your pet has a harder time keeping up during walks or has difficulty breathing/coughing, medical treatment is indicated.

The medications and doses used will depend on the symptoms in your pet. Some drugs will improve the contractions of the heart muscle or regulate the blood pressure and others will reduce the amount of fluid in the lungs to improve breathing and keep your pet comfortable.

Ideally, you would feed your dog or cat a low-salt diet to help optimize their blood pressure.

Additionally, your dog or cat should get lots of rest!

If you require more information please do not hesitate to contact us at 403-615-8016.

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