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What is a Heart Murmur?

What Does it Mean if My Pet Has a Heart Murmur?


                At Patton Veterinary Hospital, many of our patients have heart murmurs.  Murmurs can be mild and “innocent”, or they can indicate severe underlying heart disease.  But what does it mean when we say your pet has a heart murmur? 

                A murmur is an abnormal heart sound caused by turbulent or abnormal blood flow within the heart.  Normally, we should hear two distinct heart sounds often described as a “lub dub.”  A murmur causes indistinct heart sounds or a “swooshing” sound when we listen to the heart.  The most common reason for a murmur is a leaky valve within the heart. 

Murmurs are graded on how quiet or loud they are.  Though a loud murmur does not necessarily indicate severe underlying disease, it is more common for murmur intensity to increase with more advanced heart disease.  A grade one murmur is very quiet and just barely audible.  A grade six murmur is the loudest murmur and can actually be felt through the chest wall. 

                A heart murmur is not a diagnosis; it is merely a symptom of underlying disease.  The most common reason for a murmur in dogs is mitral valve disease.  The mitral valve sits between two of the four heart chambers: the left atrium and left ventricle.  If the valve does not close tightly, blood can flow back into the atrium causing disrupted blood flow and a murmur.  Other causes may be a hole between the chambers of the heart, a narrowing of a vessel stemming from the heart or a narrowing or thickening of one or more of the chambers.  Any condition causing swirling or back flow of blood within the chambers causes a heart murmur.

                What happens if we hear a heart murmur?  A quiet murmur with no associated symptoms may be something we will just monitor, listening to the heart every 6-12 months.  A louder murmur, or a dog or cat with symptoms such as coughing, exercise intolerance or other signs may necessitate some radiographs to look at the size of the heart and to see how the pet’s lungs look.  Your veterinarian may also recommend an electrocardiogram (ECG/EKG) or referral to a veterinary cardiologist or heart specialist where the heart can evaluated with an echocardiogram in which the heart is imaged with an ultrasound (sonogram) machine.  This allows the doctor to see the heart valves, measure the thickness of heart muscle and walls of the chambers and see the blood flow within the heart.  Essentially, it allows us to see if the heart is pumping blood efficiently.

                While increasing loudness may indicate progression of disease, the murmur itself is not treated and is not expected to disappear with treatment.  However, any abnormalities in heart function may be treated with a variety of medications or, occasionally surgically, to slow and control heart disease. 

                If your dog or cat has a heart murmur, we definitely want to examine your pet at least one to two times a year if not more.  Depending on the intensity of the murmur or  any underlying symptoms, your pet may also need additional tests or even the help of a cardiologist to slow progression of disease and keep your pet’s heart pumping effectively. 

Pictured is Voltron, who has a heart murmur caused by hypertrophic cardiomyopathy.  Voltron is owned by one of our nurses and his heart disease is currently well controlled with several medications.

                This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.

Source: www.veterinarypartner.com

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