A heart murmur is an abnormal heart sound that is heard when listening to the heart with a stethoscope. It is caused by abnormal turbulent blood flow. Abnormal turbulent blood flow can occur when blood passes across abnormal heart valves or across abnormal structures within the heart. It can also occur when blood flows very fast across normal structures (such as when an animal is excited).
Your veterinarian will grade the heart murmur out of 6, with 6/6 being the loudest murmur. In some instances, the louder the murmur, the more significant the abnormality within the heart. The loudness of a heart murmur does not correlate to the severity of heart disease. It is only an alarm bell that something has changed within the heart. An echocardiogram (ultrasound of the heart) is a non-invasive test that is performed to determine the cause of the murmur.
