Understanding Heart Murmurs in Dogs and Cats

Hearing that your dog or cat has a heart murmur can be unsettling—but it doesn’t always mean something serious is going on. A heart murmur is an abnormal sound heard during a physical exam with a stethoscope. Instead of the usual “lub-dub” of a healthy heartbeat, a murmur may sound like a whooshing or swishing noise. This happens when there’s turbulent blood flow within the heart.

What causes heart murmurs?
Heart murmurs in pets can be caused by a variety of things. In young puppies and kittens, a murmur may be “innocent” or physiologic, and often disappears as they grow. In adult dogs and cats, murmurs may indicate underlying heart disease, such as valve issues (like mitral valve disease in small-breed dogs), cardiomyopathy (often seen in cats), or congenital defects. Murmurs are graded on a scale of 1 to 6, with grade 1 being the softest and grade 6 being the most severe.

What happens if my pet is diagnosed with a murmur?
The first step is often a follow-up visit with us, your trusted vet clinic in Fargo, ND, to assess the grade of the murmur and check for any symptoms, such as coughing, lethargy, exercise intolerance, or difficulty breathing. Depending on your pet’s age, breed, and health status, we may recommend further diagnostics like chest X-rays, an echocardiogram (heart ultrasound), or bloodwork to evaluate heart function.

At Two Rivers Vet Hospital, we work closely with specialists and offer advanced imaging like abdominal ultrasound and referral for echocardiography, so we can better understand your pet’s condition and plan next steps.

What can be done to help?
Many pets with heart murmurs live long, happy lives with regular monitoring and—when needed—medication. Catching changes early is key. That’s why annual or semi-annual wellness exams are so important, especially for senior pets.

If your dog or cat has recently been diagnosed with a heart murmur, or you’re noticing changes in their breathing or energy levels, don’t wait. Our team at Two Rivers Vet Hospital is here to support your pet’s health with compassion, experience, and the tools to help you navigate every heartbeat.