My Dog Has a Heart Murmur, Now What?

– by Kathy Kero, DVM –

Hearing that your dog has a heart murmur can be concerning, but it doesn’t always mean they have heart failure. At Walton Gwinnett Animal Hospital in Loganville, GA, we help pet owners understand what a heart murmur means and determine the best next steps for your dog’s heart health.

What is a Heart Murmur in Dogs?

A heart murmur is an abnormal sound that your veterinarian hears when listening to your dog’s heart with a stethoscope during a physical exam. The murmur is caused by turbulent blood flow within your dog’s heart.

The heart is divided into two upper chambers called the atria and two lower chambers called the ventricles. Separating the atria from the ventricles is a one-way valve that allows blood to flow from the atria into the ventricles when the heart contracts.

In many older, small-breed dogs, the murmur your veterinarian hears is due to blood cells moving turbulently across the mitral valve, which separates the upper left atrium from the lower left ventricle. As a dog ages, the mitral valve commonly becomes thickened and develops irregular edges, preventing it from sealing as tightly as it did when your dog was younger.

This condition is known as Myxomatous Mitral Valve Disease (MMVD) and causes the murmur your veterinarian hears on the left side of your dog’s chest.

How Are Heart Murmurs Diagnosed in Dogs?

Heart murmurs are graded on a scale of 1 to 6, with Grade 1 being very soft and Grade 6 being the loudest. When your veterinarian detects a murmur, they will likely recommend one or two diagnostic tests to better evaluate your dog’s heart.

The first test is a chest X-ray (radiograph), which helps evaluate the size of your dog’s heart and determine whether there is any evidence of fluid in the lungs, a condition known as pulmonary edema or congestive heart failure. This X-ray provides a still image of the heart and lungs.

The second test is an echocardiogram, or cardiac ultrasound. This moving image of the heart provides valuable information that allows your veterinarian to determine the exact cause of the murmur, assess how well the heart is functioning, and decide whether your dog would benefit from medication.

Medications for Dogs with Heart Murmurs

There are several medications your veterinarian may prescribe for a dog with a heart murmur. Some medications help the heart pump more effectively, while others have been shown to slow the progression of congestive heart failure. Additional medications may be used to help remove fluid from the lungs if congestive heart failure develops.

Once your dog is prescribed heart medication, they will typically remain on it for the rest of their life, with regular monitoring by your veterinarian.

If your dog has been diagnosed with a heart murmur and you have questions about their diagnosis or treatment options, please contact us at Walton Gwinnett Animal Hospital in Loganville, GA, to schedule a comprehensive physical exam and consultation with one of our veterinarians. Early diagnosis and ongoing monitoring can help your dog maintain the best possible quality of life.