Detecting Symptoms for a Dog's Heart Murmur

Not all dogs with heart murmurs show symptoms.
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A heart murmur in your dog can be anything from completely normal to life-threatening, depending on the cause. While there are not always noticeable symptoms, when symptoms are present, getting your dog prompt veterinary attention will help diagnose the situation and either put your mind at ease or help get him on the road to recovery.

Heart Murmur Symptoms

Sometimes heart murmurs are completely asymptomatic, but you may notice changes. If your pal is coughing, has a loss of appetite, is weak or fatigued, has a bluish tongue or gums, lost his stamina, has an especially fast or slow heartbeat, or is having problems breathing, it's time to take a trip to the vet. These may be signs of a number of different illness, including other heart problems, but they all require medical attention.

Potential Causes

A heart murmur may be physiologic, caused by a genetic defect or physical changes over time, or pathologic, caused by an illness. Genetic heart murmurs may be caused by weakened heart valves, thickened or thinned heart valves, narrowing of large blood vessels, or a hole connecting the chambers of the heart where they shouldn't meet. A heart murmur may develop due to bacterial infection in the heart valves, anemia, hypoproteinemia (insufficient protein in the blood), a weakened heart muscle or a lesion on the heart valve.

Detecting the Murmur

Your vet will use a stethoscope to first detect a heart murmur. Instead of the usual lub dub of the heart, there will be a third sound that indicates a murmur. This sound is ranked from Grade I, barely audible in a quiet room, to Grade VI, still audible when the stethoscope is slightly removed from the chest. Your vet will also determine whether the murmur is systolic, occurring during the lub sound, or dystolic, occuring during the dub, as this will help diagnose the cause. She may also recommend chest X-rays, bloodwork and an electrocardiogran (ECG) to get a full picture of the heart structure and the health of your dog.

How Serious Is It?

The seriousness of a murmur depends entirely on what caused it. Young puppies may have what is considered an innocent murmur, a low-grade murmur that will disappear around four or five months of age. Older dogs may have a genetic murmur that has little impact on their lives, while others will need corrective surgery or medication. If an infection is to blame, the seriousness will depend on how advanced the infection is.