Heart Murmur in Dogs and Cats

Has your dog or cat has been diagnosed with a heart murmur? If you are concerned and have questions about what a heart murmur is, read on. 

  Veterinary Technician  Nicole Schliemann assists Dr. Sarah Mueller listening for a heart murmur.

Veterinary Technician Nicole Schliemann assists Dr. Sarah Mueller listening for a heart murmur.

Heart murmur is a term used to describe the sound of turbulent blood flow heard when listening to the heart with a stethoscope. There are many causes of heart murmurs: degeneration of the valves, dilating of the heart, infection, pregnancy, anemia, and a variety of congenital abnormalities. Puppies and kittens can have a soft murmur that usually goes away by four months of age. This type is referred to as an “innocent” or “benign” murmur. If a puppy’s murmur is loud, or persists beyond four months of age, or is accompanied by clinical signs, it may be caused by a congenital abnormality. 

Heart murmurs are often noted on physical examination without any clinical signs being noted by the owner. Once a heart murmur is identified, the veterinarian will grade its intensity and note the location of the murmur. An ultrasound of the heart, called an echocardiogram, is used to look at all the chambers of the heart and determine the cause for the murmur. Chest x-rays will assist the veterinarian in determining the size of the heart and if there are any signs of heart failure.  

A pet with a murmur sometimes requires medical therapy depending on the cause of the murmur and if any associated conditions are present. 

The prognosis for a dog or cat with a heart murmur is highly variable due to numerous different disorders associated with the condition.