Heart Murmurs in Dogs: Symptoms and Diagnosis

What is It?

A heart murmur is an additional heart vibration produced by a disturbance in blood flow.

What Causes It?

Extra heart beats are measured in intensity Grades I-VI and fall into three categories.

  • Innocent of physiologic – Need no further investigation as they will not affect the life of the dog.
  • Structural problems – By product of heart disease.
    • Structural issues of the heart are a sign of heart disease. These issues affect the regulated blood flow through the 4 chambers of the heart. The abnormality may be a valve not fully closing, a thickening/narrowing of a valve or large blood vessel, or an abnormal hole between the heart chambers or between two arteries that are usually separate. All these issues create an abnormal blood flow, which in turn forces the heart to create more pressure to move the blood through. Structural problems can be hereditary and present from birth. Heart murmurs may present because of heath events such as mitral insufficiency, bacterial infection that localizes on a heart valve and dilated cardiomyopathy.
  • Extracardiac problems – Not a product of heart disease.
    • These issues are known as “functional heart murmurs”. They can result from anemia, hypoproteinemia, blood thinning, fever or infection, pregnancy, obesity, or emaciation.

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What Are The Symptoms?

The symptoms of a heart murmur are simply the abnormal rhythm itself. All other symptoms may point to the root cause of the murmur.

Is it Life Threatening?

Yes but every murmur is different. Life expectancy greatly depends on grade, categorization, and speed of treatment. Aforementioned, some murmurs are completely safe and require no treatment.

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How is It Diagnosed?

Diagnosing a heart murmur will typically happen during a routine vet examination of your dog. The murmur will be detected with a stethoscope. Your vet will use the scope to discern where in the 4 chambers of the heart the murmur is coming from.

If the murmur is rated as a Grade III higher further testing will be required. An ultrasound heart scan, a chest x-ray, or an ECG will be administered to gather more information and classify the condition.

What Are The Treatments?

Grade I-II will not require treatment, but they should be scanned every 6-12 months to ensure the murmur does not worsen. Higher grade murmurs will receive medicine including angiotensin-converting enzyme inhibitors, diuretics, and positive inotropes.

There are other medicines in the clinical stages that have shown promise to extend the life of dogs with murmurs. Be sure to ask your vet about the latest developments.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pup’s condition, please make an appointment with your veterinarian. Or, consult a virtual vet here.