A heart murmur is a sound that is made when a heart beat is abnormal.

It is a swishing sound that can occur during certain parts of the heart beat (systolic or diastolic) or can be constant throughout the beat (continuous). Murmurs can also occur on one side of the heart or the other, and can be louder at certain areas of the heart. Heart murmurs are graded on a scale of either 5 or 6. The higher the number, the louder the heart murmur. Some heart murmurs can be so severe that you can actually "feel" the murmur with your hand against the side of your pet's chest. The loudness of the murmur does not necessarily correlate with the severity of the problem causing the murmur.

Types of Murmurs

A murmur is a relatively generic description which can mean a multitude of different heart problems. Some murmurs may never cause problems, and some can be serious and life-threatening at the time of detection.

The swishing sound of a murmur comes from blood not going the right way. There can be a hole in the heart, there can be growths that get in the way of blood flow, or the heart can be enlarged causing the abnormal blood flow.

Puppies can have "innocent" murmurs which go away as they grow up, but some murmurs in puppies are the result of very serious congenital defects which can stunt growth and not allow them to reach even 1 year of age. Small breed dogs commonly develop heart murmurs as they age due to disease of the heart valves which does not allow them to close correctly. Some dogs live with murmurs for many years without any complications. Large dogs more commonly develop heart disease as a results of heart muscle issues.

Diagnosing the Cause

There are two steps you should take when you find out your dog has a murmur. These steps are finding out what the murmur is being caused by, and seeing if it is causing any other problems for your pet.

The first step is a veterinarian examining your animal and listening to the murmur. The differences mentioned above (location of the murmur, type of murmur) can tell your veterinarian a lot about what possible causes are. In addition, a few different tests your veterinarian may recommend include a chest x-ray, EKG, blood pressure, and cardiac ultrasound.

A chest x-ray will show if your pet has any heart enlargement or lung problems. This can help determine medications for your pet. An EKG can help determine the cause of heart problems. It can indicate certain parts of the heart that are having problems, but it can also be very non-specific for some problems.

The best way to diagnose heart problems is by cardiac ultrasound or echocardiogram. This is doing an ultrasound of the heart and actually watching it beat and looking at all the structures of the heart. Your veterinarian may recommend you see a specialist for this procedure, or they may perform it and send the results to a specialist for evaluation.


There are a few different ways of treating heart problems. Some problems can be fixed with surgery - often these are congenital problems. Usually surgery on the heart requires going to a specialist. Some problems can be treated medically. Cardiac drugs are a very important part of extending the life of an animal with heart problems. These can include medications to decrease fluid in the lungs, help the heart beat stronger, stop arrhythmias (abnormal beats), or lower blood pressure. The medications used depend on the type of problem and the complications your pet is having.

A very important part of treatment involves you monitoring your pet at home. Signs that they are having problems include increased rate of breathing, coughing, exercise intolerance, swelling of the abdomen, swelling of the limbs, and problems breathing. This can be an emergency! See your veterinarian immediately if you notice any of these signs.

Finally, a pet with a heart murmur should be monitored regularly by a veterinarian. Talk to your vet about how often to have tests and check-ups redone. Even if they are on no medications, your pet should be checked at least every six months so that they can be put on medications if heart problems progress.

Heart murmurs can be very serious, but with the right evaluation and treatment, we can still often give your pet a long happy life.


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