Heart murmur is likely controllable

Common ailment can be serious, but not typically

Most heart murmurs are physiological or ‘innocent’ i.e. they do not cause a problem and will eventually resolve on their own.

When we adopted our 12-week-old Labrador retriever puppy, we were told that she had a slight heart murmur but that it was an “innocent” murmur, i.e., not serious. We took her to our own veterinarian who confirmed the existence of the heart murmur but also told us that our puppy was in excellent health and that the murmur was probably not serious. She told us she would recheck the heart prior to her spay operation and, if the murmur was still present, she would do a cardiac evaluation. Should we be concerned about this or is this quite a common occurrence?

Heart murmurs are quite common and usually the result of increased “turbulence” of the blood flow in the heart. Most are innocuous and do not require any treatment but others can be caused by a medical problem such as faulty heart valves or, in puppies, due to congenital heart defects such as a hole in the walls separating the chambers of the heart.

In young dogs, heart murmurs can also occur due to rapid growth or with anemia or dehydration.

In fact, anything that can increase the turbulence of blood flow through the heart chambers can result in a heart murmur.

Heart murmurs are usually rated according to their intensity. A grade 1 or 2 heart murmur is of low intensity and can easily be missed when listening with a stethoscope. No treatment is necessary but the patient is usually monitored regularly for symptoms such as coughing or lethargy.

A grade 3 or 4 heart murmur is considered more serious. This type of murmur is easy to hear with a stethoscope and often leads to a persistent cough and poor exercise tolerance. Medication may be required at this stage to help the patient live comfortably.

A grade 5 or 6 murmur is very serious and patients with this grade of heart murmur need medication daily. These murmurs eventually lead to congestive heart failure. Signs of heart failure include poor exercise tolerance, coughing, weight loss and difficulty breathing.

Should your puppy still have a heart murmur at the next visit to the veterinarian, the cause, type and severity of the murmur will need to be assessed in order to decide your next course of action.

Fortunately, as mentioned, most heart murmurs are physiological or “innocent” i.e. they do not cause a problem and will eventually resolve on their own.

This is why your veterinarian has taken a “wait and see” approach and will recheck your puppy’s heart at the next visit. If the heart murmur is still present, your veterinarian will likely suggest a cardiac workup, which may include an electrocardiogram, chest X-rays, laboratory tests and/or ultrasound. The results will help your veterinarian decide on the next course of action as well as your dog’s prognosis.