This phrase always provokes a look of fear and concern from pet owners. More than once I have seen it produce tears. But I am quick to point out that a heart murmur is not necessarily
the sign of a major health concern.
A heart murmur is an abnormal heart sound that can be heard with a stethoscope. Instead of the normal “lub-dub lub-dub” we hear something like “lub-woosh”. That woosh sound means that blood flow in the heart is abnormally turbulent, either due to blood flowing in the wrong direction or through too small of an opening. Sometimes the underlying cause of a murmur is very serious, sometimes it is benign, but mostly it is somewhere in the middle – a problem that needs to be monitored, but isn’t an emergency.
This abnormal blood flow is caused by changes to the normal structure of the heart, and can either be congenital (something the pet was born with) or acquired (something that has occurred over time).
Heart murmurs are graded on how loud they are. A grade 1 murmur is very soft, while a grade 5 or 6 is so pronounced that the animal’s chest will actually vibrate with each heart beat. Some of the time the loudness of the murmur correlates with severity of disease, but we can’t reliably use loudness to predict whether or not a murmur is the sign of something more serious.
The only way to have a heart murmur adequately evaluated is to have an ultrasound, or echosonography done of the heart. This test is great because it is noninvasive and gives us a great deal of information about the inner workings of the heart. I personally try to refer my clients to a veterinary cardiologist to have a heart murmur evaluated. These veterinarians have devoted their careers to understanding the heart, and I am most comfortable consulting them for a diagnosis and treatment plan.
So…if your veterinarian someday says to you “I hear a heart murmur,” don’t panic. Take a deep breath, and ask any questions you may have, have it further evaluated, and take heart (I couldn’t resist the pun – sorry!), it most likely isn’t as scary as it sounds.