My Pet Has a Heart Murmur: Now What?

By: Emily Gaugh, DVM

TVMA Member
Houston, TX

Published August 2014

What is a heart murmur?

A heart murmur is an abnormal sound that can be heard when listening to your pet’s heart with a stethoscopeA medical instrument for listening to the action of someone's heart or breathing, typically having a small disk-shaped resonator that is placed against the chest and two tubes connected to earpieces.. The heartbeat normally has two beats, but a murmur is an extra sound that can be heard, often overlapping the normal heartbeats. This is usually the first finding that gives your veterinarian a clue to a possibly underlying heart disease. Based on your pet’s age, breed and other exam findings, your veterinarian can often predict the cause of the abnormal sound. However, further testing is often recommended to confirm the cause and determine the significance of the murmur.

What types of murmurs are there?

Innocent Murmurs: These are often heard in young puppies and cats or sometimes cats of any age and are not associated with underlying heart disease. These have the potential to go away on their own with time. It is usually recommended to listen again to the pet’s heart in the near future (one to three months) to determine if it has gone away. If it is still present, further diagnostics may be recommended.

CongenitalPresent from birth. Murmurs: This type is found in young animals that were born with a heart defect. It is strongly recommended to perform radiographs (X-rays) and cardiacOf or relating to the heart. ultrasound to confirm a diagnosis. Surgical intervention is often necessary.

Acquired Murmurs: An acquired murmur develops over time and is often the result of progressing heart disease in older patients. With this type, the loudness of the sound often correlates with the severity of the heart disease.

Functional Murmurs: A murmur that is a result of abnormalities not directly due to heart disease is termed a functional murmur. There are many disease processes that can cause one but are not related to the heart itself. Examples include low levels of blood (anemia), emaciationThe state of being abnormally thin or weak., low protein levels or infection. These murmurs typically resolve when the underlying disease is treated.

How significant is my pet’s heart murmur?

Your veterinarian may be able to describe the loudness of a murmur by giving it a “grade.” They are graded on a scale of one to six. Grade one is a very soft, almost inaudibleUnable to be heard. murmur. A grade six is a very loud sound and may be felt through the chest wall. The significance of the murmur will also be determined based on individual factors such as your pet’s breed, age and clinical symptoms.

My veterinarian wants to run some tests. Is this necessary?

Your veterinarian may need to perform further testing to help determine the cause and significance of a murmur and the extent of the heart disease. A radiograph or X-ray of the pet’s chest is often the first diagnostic step. Chest radiographs can show enlargement of certain areas of the heart, which may indicate which valve is affected. Radiographs are also helpful for assessing the size of the heart vessels, as well as examining the lungs for fluid accumulation, helping stage the progression of disease.

Often additional visualization of the heart with a cardiac ultrasound is beneficial. An ultrasound can actually see into the heart. This helps to visualize the heart valves, look for blood clots, measure the thickness of the walls of each heart chamber and even measure cardiac output. Your veterinarian may also ask to perform an ultrasound of the heart called an echocardiogram, or an electrocardiogram (ECG), which will show the electrical conduction in the heart to screen for any arrhythmiasA condition in which the heart beats with an irregular or abnormal rhythm.. Many heart diseases will cause an irregular heart rhythm as well as a murmur, and these will need to be treated as well.

How is a murmur treated?

The murmur itself will not be treated, but the underlying cause will determine the steps necessary to keep your pet happy and healthy.

Emily Gaugh, DVM, is a graduate of Kansas State College of Veterinary Medicine who lives in Houston, Texas. Dr. Gaugh practices at Westbury Animal Hospital.

  • Crystal

    Echo (echocardiogram) OR ECG (electrocardiogram)