Heart Murmurs in Dogs

When a veterinarian uses a stethoscope to listen to your dog’s heart, chances are that the heart will sound normal. However, in some cases, a veterinarian may hear an abnormality such as a heart murmur.

Sonya Wesselowski, a clinical assistant professor of cardiology at the Texas A&M College of Veterinary Medicine & Biomedical Sciences, said heart murmurs are abnormal heart sounds caused by turbulent or rapid blood flow within the heart. In dogs, heart murmurs are usually the result of a leaky or narrowed heart valve.

Heart murmurs are not always a cause for concern. Wesselowski said that some soft heart murmurs could be normal in growing puppies less than 6 months of age. However, most heart murmurs in dogs do indicate that there is an underlying abnormality of the heart. In some cases, the heart murmur could be caused by a congenital heart defect the dog was born with, or due to a heart disease that develops later in life.

How can you know if your dog has a heart murmur? Wesselowski said that regular examinations with your veterinarian are crucial for detection of heart murmurs, as a heart murmur itself does not cause any signs or symptoms. Instead, a heart murmur is a finding that suggests a cardiac problem may be present.

If a heart murmur is detected in your dog, Wesselowski recommended additional testing to investigate for an underlying heart condition.

“A cardiac ultrasound, also known as an echocardiogram, is the definitive test to determine the cause of your dog’s heart murmur and diagnose any underlying heart disease,” Wesselowski said. “Your veterinarian may also choose to perform an X-ray of your dog’s chest as an initial screening test to look for evidence of heart enlargement.”

Even if a dog is not showing signs of heart disease such as lethargy, exercise intolerance, cough, difficulty breathing, or fainting spells, further investigation into the cause of a heart murmur is always a good idea, Wesselowski said. These tests can help to determine if your dog would benefit from starting cardiac medications or if they should have more frequent check-ups to monitor their heart condition.

In general, most heart murmurs are an indication of an underlying heart condition and should be taken seriously. If your veterinarian detects a heart murmur in your dog, be sure to investigate the murmur and determine the best way to protect your dog’s heart health.

Pet Talk is a service of the Texas A&M College of Veterinary Medicine & Biomedical Sciences.