When your dog is diagnosed with a heart murmur, it's natural to feel concerned. 

 But before panic sets in, it’s worth knowing that not all murmurs are a cause for alarm. Some are mild and manageable with the right support — and in many cases, natural supplementation can make a meaningful difference.

Let’s explore what a heart murmur in dogs really means, what causes it, and how you can support your pup’s heart naturally.

What is a Heart Murmur in Dogs?

A heart murmur is essentially an unusual sound your vet hears when listening to your dog’s heartbeat. Instead of the familiar “lub-dub”, a murmur creates a whooshing sound — a sign that blood is flowing abnormally within the heart.

It’s important to understand that a heart murmur in dogs isn’t a disease in itself, but a symptom. It can signal anything from a harmless quirk in circulation to a more serious underlying heart condition. Sometimes, puppies are born with murmurs that disappear as they grow. Other times, murmurs develop later in life as the heart ages or weakens.

Heart Murmur in Dogs Stages

Veterinarians use a grading system — from Grade I (barely audible) to Grade VI (very loud) — to describe how pronounced a murmur is.

Grade I–II: Soft murmurs often detected only during routine check-ups.

Grade III–IV: Moderate murmurs, possibly linked to mild or moderate heart disease.

Grade V–VI: Loud murmurs typically associated with more advanced heart issues.

Beyond sound, your vet may also stage your dog’s heart condition — from Stage A (at risk but no symptoms) to Stage D (advanced heart disease). Knowing the stage helps guide treatment and lifestyle adjustments, ensuring your dog receives the right care at the right time.

Heart Murmur in Dog Symptoms

In early stages, your dog may show no symptoms at all — which is why regular vet check-ups are so crucial. As a heart murmur dog condition progresses, you might start noticing subtle signs that the heart is working harder than it should.

Common symptoms include:

Lethargy or reduced stamina on walks

Coughing, especially at night or after activity

Rapid or laboured breathing

Fainting spells or collapsing

Loss of appetite or gradual weight loss

Restlessness, especially during sleep

If your dog displays any of these signs, don’t delay a visit to your vet. Early detection and supportive care can dramatically slow progression and improve quality of life.

Heart Murmur in Dog Causes

There’s no single cause for heart murmurs — they’re a result of how blood moves through the heart. But some underlying issues are more common than others:

Congenital defects: Heart abnormalities present from birth.

Valve disease: Especially mitral valve degeneration, common in small and older breeds.

Cardiomyopathy: A weakening of the heart muscle.

Infections or inflammation: Such as bacterial endocarditis.

Anaemia or thyroid imbalance: Which can alter blood flow and heart rhythm.

Certain breeds — including Cavalier King Charles Spaniels, Poodles, and Dachshunds — are more genetically prone to heart murmurs. Awareness and proactive monitoring are key for these dogs.

Heart Murmur in Older Dogs

A heart murmur in older dogs is most often linked to degenerative mitral valve disease (DMVD). Over time, the valve between the heart’s chambers thickens and leaks, allowing blood to flow backwards and creating that telltale murmur.

While this condition can’t be reversed, it can be managed. Senior dogs with heart murmurs benefit from a calm lifestyle, regular vet monitoring, and a heart-conscious diet — low in sodium and rich in antioxidants. Supplements that support cardiac muscle and circulation can also be a valuable part of long-term care.

Natural Supplements to Support a Dog with a Heart Murmur

At Petmima, we believe that holistic wellbeing comes from both medical and natural care. When it comes to supporting a heart murmur dog, supplements that nourish the cardiovascular system can help reduce oxidative stress and support healthy blood flow.

Cardio Care is our premium heart health formula designed to naturally support dogs with heart murmurs or early-stage heart disease. It combines vital nutrients and antioxidants that work together to strengthen cardiac function and promote healthy circulation.

Key Ingredients & Benefits:

Coenzyme Q10 (CoQ10) – A powerful antioxidant that helps the heart produce energy and protects against free radical damage.

L-Carnitine – Supports energy metabolism in heart cells, helping maintain optimal cardiac performance.

Omega-3 Fatty Acids (from fish oil) – Helps reduce inflammation, supports healthy blood flow, and promotes overall cardiovascular health.

Vitamin E & Selenium – Antioxidants that protect heart tissue from oxidative stress and age-related damage.

Final Thoughts

Hearing that your dog has a heart murmur can be confronting, but it’s not a reason to lose hope. With early detection, consistent vet care, and natural support, many dogs live full, joyful lives well into their senior years.

By combining veterinary guidance with natural supplements — you’re taking a proactive step toward supporting your dog’s heart health from the inside out. Because love, after all, beats strongest in a healthy heart.