News // 3.2.25

Understanding Heart Murmurs in Pets

Understanding Heart Murmurs in Pets

A heart murmur is a term that often raises concern among pet owners. If your veterinarian has recently detected a heart murmur in your dog or cat, you may wonder what this means and how it could impact your pet’s health. In this article, we’ll explain what heart murmurs are, their potential causes, how they are diagnosed, and what steps you can take to ensure your pet receives the best possible care.

What is a Heart Murmur?

A heart murmur is an abnormal sound heard when listening to the heart with a stethoscope. Normally, a healthy heart makes two distinct sounds—the familiar “lub-dub” created by the closing of the heart valves and an extra sound that has a “whooshing” or “shooshing” quality, which occurs due to turbulent blood flow within the heart.

What Causes a Heart Murmur in Pets?

In a healthy heart, blood flows smoothly and without disruption. However, in pets with certain heart conditions, blood flow becomes turbulent, leading to the development of a murmur.

Degenerative valve disease is one of the most common causes of heart murmurs in older dogs, where the heart valves become thickened and nodular. This prevents them from closing properly, allowing blood to leak backward when the heart contracts. Other causes of heart murmurs include congenital heart defects, heart muscle diseases, and anemia.

What Does a Heart Murmur Mean for My Pet?

A heart murmur indicates that your pet may have an underlying heart condition. However, not all murmurs are cause for immediate concern. Some pets can live with mild murmurs without developing symptoms, while others may progress to more serious heart disease.

One of the challenges with heart disease is that many pets do not show symptoms until the disease is quite advanced. Detecting a heart murmur early provides an opportunity for early diagnosis and management before serious complications arise.

Understanding Murmur Grades

Heart murmurs are classified into six grades based on their intensity or loudness:

  • Grade 1: Very soft, barely audible.
  • Grade 2: Soft but easily heard.
  • Grade 3: Moderately loud.
  • Grade 4: Loud murmur, often heard on both sides of the chest.
  • Grade 5: Very loud murmur, with a vibration that can be felt.
  • Grade 6: Extremely loud murmur, heard even without a stethoscope touching the chest.

While louder murmurs can sometimes indicate more significant disease, this is not always the case—some mild conditions can cause loud murmurs, and some serious conditions can have quieter murmurs.

How is a Heart Murmur Diagnosed?

The gold standard for diagnosing heart disease in pets is an echocardiogram—an ultrasound of the heart. This noninvasive test provides a detailed image of the heart’s structure and function, allowing veterinarians to determine the cause of the murmur, assess disease severity, and develop a treatment plan if necessary.

At Allambie Vet, our experienced veterinarians, Dr Jane Vine and Dr Faon Mudie, perform heart ultrasounds in-house. For more complex cases or pet owners seeking a specialist opinion, we also offer consultations with Specialist Cardiologist Dr. Damon Leeder, who regularly visits our hospital to perform advanced cardiac assessments.

Treatment and Management

A heart murmur itself does not require treatment—what matters is the underlying cause of the murmur. Some heart conditions require no immediate treatment, while others benefit from early intervention. Research has shown that starting heart medication at the right stage (such as when heart enlargement is detected) can delay the progression to congestive heart failure by up to 15 months in dogs.

What Happens if I Don’t Investigate a Heart Murmur?

If a pet with an undiagnosed murmur progresses to congestive heart failure, it may develop severe symptoms that require emergency treatment, including:

  • Shortness of breath or difficulty breathing
  • Lethargy and weakness
  • Persistent coughing
  • Increased respiratory rate and effort
  • Collapse or fainting episodes

In advanced cases, pets may require hospitalisation, oxygen therapy, and intensive care. In some cases, if heart failure is severe, it may not be reversible.

Should I Book a Heart Ultrasound for My Pet?

Choosing to monitor your pet’s heart murmur with an ultrasound can provide peace of mind and allow for early intervention if needed. If you decide not to pursue further diagnostics, it is essential to watch for any changes in your pet’s behaviour and contact your veterinarian if any concerning symptoms arise.

At Allambie Vet, we are here to help you make the best decision for your pet’s health. If you have any questions about heart murmurs or would like to book a heart ultrasound, please don’t hesitate to contact our team.

Contact Us

📍 Allambie Vet – Northern Beaches, Sydney

📞 (02) 9905 0505
📧 nurses@allambievet.com.au
🌐 www.allambievet.com.au

We care about your pet’s heart health and are here to provide compassionate, expert care every step of the way. 

Contact us today to book an appointment or speak with our team.

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