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Heart Murmurs Speak Volumes to Veterinarians

Pet Column for the week of February 15, 2012

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Brittany Way Rose
Information Specialist

"Lub-dub, lub-dub" beats the normal heart over and over. When the heart is making any other sounds, however, further investigation may be needed to determine just what the heart is saying.

According to Dr. Mauria O'Brien, a veterinarian board certified in emergency and critical care at the University of Illinois Veterinary Teaching Hospital in Urbana, one such irregular heart sound, a murmur, has different meanings depending on the age and breed of pet.

A heart murmur indicates turbulence in the flow of blood. Normally, blood flows only forward through the heart's chambers, making a distinct "lub dub." A murmur may indicate that blood is moving backwards or is being pushed through an opening that is narrower than normal.

If your pet has a heart murmur, your veterinarian will grade the murmur on a scale of 1 to 6, depending on how loud the murmur is.

It can be normal for puppies younger than 16 weeks old to have a "baby" murmur. Your veterinarian will to listen to your puppy's heart at its routine puppy wellness appointments (at 8 weeks, 12 weeks, and 16 weeks) in order to determine whether the murmur is a "baby," or "innocent," murmur that will go away as the puppy ages. If a murmur is still heard beyond four months of age, the murmur could be considered a congenital defect, and your veterinarian will likely refer you to a veterinary cardiologist for a complete diagnostic work-up.

Acquired heart murmurs are those arising as your pet ages. In dogs, signs of a heart problem include exercise intolerance and cough, whereas cats often show no early warning signs.

Heart murmurs themselves may indicate a variety of underlying diseases. For example, in cats a murmur may indicate hyperthyroidism or hypertension as well as various heart diseases. The underlying cause of an acquired murmur must be identified in order to determine the correct treatment.

Radiographs (x rays), ECGs, and echocardiograms are among the diagnostic imaging approaches that can help your veterinarian understand what is going on with your pet's heart. In certain cases, examination by a board-certified veterinary cardiologist will be advisable to reach a diagnosis and effective treatment plan.

The best way to catch a heart murmur in its earliest stages is to have regular examinations for young and adult pets so your veterinarian can listen to what your pet's heart has to say. If you have further questions about heart murmurs in pets, contact your local veterinarian.