Heart murmurs in dogs can be a cause for concern among pet owners. These abnormal heart sounds can vary in intensity and may indicate an underlying cardiovascular issue. In this article, we will delve into the world of heart murmurs in dogs, exploring their causes, symptoms, diagnosis, treatment options, and much more. Understanding this condition is vital for ensuring your furry friend's health and happiness.

heart murmurs in dogs

Understanding Heart Murmurs

Heart murmurs in dogs can be puzzling for many pet owners, but they are a critical indicator of underlying cardiac issues. To truly understand heart murmurs, we must delve into their nature and causes.

What is a Heart Murmur?

A heart murmur is an abnormal sound that emanates from your dog's heart during its regular beating cycle. This sound, akin to a whoosh or a swishing noise, can be detected by a trained veterinarian using a stethoscope.

Heart murmurs occur when there is turbulence in the flow of blood through the heart. Typically, blood flows smoothly through the heart's chambers and valves, but when there are irregularities, such as obstructions or leaks, the blood's flow becomes turbulent, resulting in a heart murmur.

These murmurs can range from being faint and benign to loud and indicative of a severe cardiac condition. It's important to note that a heart murmur is not a disease in itself but rather a symptom of an underlying problem.

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Causes of Heart Murmurs

Heart murmurs in dogs can have various origins, and understanding these causes is fundamental in determining the appropriate course of action. Some of the common causes include:

  • Congenital Heart Defects: Some dogs are born with structural abnormalities in their hearts, making them more prone to murmurs.
  • Acquired Heart Diseases: Dogs can develop heart murmurs as they age due to conditions like degenerative valve disease or dilated cardiomyopathy.
  • Anemia: A low red blood cell count can lead to a heart murmur as the blood becomes thinner, resulting in increased turbulence.

Signs and Symptoms

Detecting heart murmurs in dogs often requires a keen eye and an understanding of the common signs and symptoms associated with this condition.

Detecting Heart Murmurs

While your veterinarian is the ultimate authority in diagnosing heart murmurs, there are a few signs you can watch out for at home:

  • Abnormal Heart Sounds: If you notice any unusual sounds when listening to your dog's heartbeat, such as a swishing or whooshing noise, it's essential to seek professional evaluation.
  • Change in Breathing: Rapid or labored breathing, especially during rest or minimal activity, can be a sign of an underlying heart issue.
  • Coughing: Persistent coughing, especially at night or after physical activity, may be an indication of heart trouble.

Common Symptoms

Dogs with heart murmurs may exhibit various symptoms, and these can vary depending on the severity of the condition. Some common signs to be aware of include:

  • Lethargy: A decrease in energy levels or reluctance to engage in physical activities.
  • Loss of Appetite: Reduced interest in dog food or a noticeable decline in eating habits.
  • Weight Loss: Unexplained weight loss can be a red flag.
  • Weakness: Generalized weakness or difficulty in moving.
  • Fainting Spells: In severe cases, dogs with heart murmurs may faint due to insufficient blood flow.

Understanding these signs and symptoms and acting promptly can make a significant difference in your dog's health and well-being. Remember that early detection and intervention are key to managing heart murmurs effectively.

Diagnosis and Evaluation

Diagnosing and evaluating heart murmurs in dogs is a meticulous process that involves a combination of veterinary expertise and advanced diagnostic tools. Proper assessment is crucial to determine the underlying cause and severity of the condition.

Veterinary Examination

The first step in diagnosing a heart murmur involves a comprehensive veterinary examination. During this examination, your veterinarian will:

  • Listen to Heart Sounds: Using a stethoscope, your veterinarian will carefully listen to your dog's heart sounds. They will pay close attention to the rhythm, rate, and any abnormal sounds such as murmurs.
  • Gather Medical History: Your veterinarian will inquire about your dog's medical history, including any previous heart-related issues, medications, and changes in behavior or activity levels.
  • Physical Examination: A thorough physical examination will be conducted to check for any other signs of illness or discomfort.

Diagnostic Tests

While a physical examination can provide essential information, it often necessitates further diagnostic tests to pinpoint the cause and severity of the heart murmur. Some common diagnostic tests include:

  • Echocardiogram: This ultrasound of the heart provides detailed images of the heart's structure and function, helping to identify any structural abnormalities, valve problems, or congenital defects.
  • Chest X-rays: X-rays can reveal the size and shape of the heart and can be useful in assessing potential heart enlargement.
  • Electrocardiogram (ECG or EKG): An ECG records the electrical activity of the heart and can help identify irregular heart rhythms.
  • Blood Tests: These tests can determine if there are any underlying conditions contributing to the heart murmur, such as anemia or infections.

Once the diagnostic process is complete, your veterinarian will be able to grade the heart murmur and provide a clearer picture of its origin and implications for your dog's health.

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Types of Heart Murmurs

Understanding the different types of heart murmurs is essential for both veterinarians and pet owners. Heart murmurs can be classified into two primary categories based on when they occur in the cardiac cycle:

Systolic Murmurs

Systolic heart murmurs are the most commonly encountered in dogs. They occur during the heart's contraction phase, when the left ventricle pumps blood into the aorta and out to the body. These murmurs are typically graded on a scale from I (soft) to VI (loud), with the intensity often correlating with the severity of the underlying condition.

Systolic murmurs can be caused by a variety of factors, including:

  • Valvular Disease: Degenerative changes in the heart valves can lead to regurgitation, causing turbulent blood flow and murmurs.
  • Hypertrophic Cardiomyopathy: This condition involves thickening of the heart muscle, obstructing blood flow and causing murmurs.

Diastolic Murmurs

Diastolic murmurs are less common but often more concerning. They occur during the heart's relaxation phase, when the left ventricle fills with blood. These murmurs can be indicative of severe underlying issues, such as:

  • Aortic Insufficiency: When the aortic valve doesn't close properly, blood flows back into the left ventricle, creating turbulence and a diastolic murmur.
  • Mitral Stenosis: This condition involves narrowing of the mitral valve, obstructing blood flow and leading to diastolic murmurs.

Understanding the type of murmur and its grading is crucial for determining the appropriate treatment and management plan. Your veterinarian will use this information to provide you with the best guidance for your dog's specific condition.

Grading Heart Murmurs

Grading heart murmurs is a precise method used by veterinarians to assess the intensity of the murmur and, consequently, the severity of the underlying heart condition. Understanding the grading system is essential in determining the appropriate course of action for your dog's care.

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How Murmurs are Graded

Heart murmurs are graded on a scale from I to VI, with each grade indicating a different level of loudness and intensity:

  • Grade I: These are soft murmurs, often barely detectable even with a trained ear. They are typically considered benign and may not require immediate treatment.
  • Grade II: Murmurs at this level are soft but more readily heard with a stethoscope. They are still generally considered benign but may warrant closer monitoring.
  • Grade III: Moderate-intensity murmurs that are easily heard with a stethoscope. These murmurs often suggest an underlying heart condition that requires attention and monitoring.
  • Grade IV: These are loud murmurs that can be heard without a stethoscope. They often indicate a significant underlying heart issue that needs prompt evaluation and treatment.
  • Grade V: Very loud murmurs that can be felt as well as heard. Grade V murmurs are indicative of severe heart problems and require immediate intervention.
  • Grade VI: These are the loudest murmurs and are often associated with critical heart conditions that demand emergency care.

Importance of Grading

Grading heart murmurs serves several critical purposes:

  • Assessment: It helps veterinarians assess the severity of the heart condition and its impact on your dog's health.
  • Treatment Guidance: The grade of the murmur guides the choice of treatment and management strategies.
  • Monitoring: Grading allows for ongoing monitoring of your dog's condition, helping veterinarians make informed decisions about treatment adjustments.

Remember that while the grading system provides valuable information, it is just one aspect of evaluating your dog's overall cardiac health. Your veterinarian will consider other factors, such as diagnostic test results and clinical symptoms, to develop a comprehensive treatment plan.

Common Breeds Prone to Heart Murmurs

Certain dog breeds are genetically predisposed to heart murmurs, making it crucial for owners of these breeds to be vigilant about their pets' cardiac health. While heart murmurs can affect any breed, some are more commonly associated with this condition.

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Breeds with Higher Risk

  • Cavalier King Charles Spaniel: This breed is particularly susceptible to mitral valve disease, which often leads to heart murmurs.
  • Boxer: Boxers are known for their increased risk of developing aortic stenosis, a condition associated with diastolic heart murmurs.
  • Dachshund: Dachshunds are prone to aortic valve disorders, which can lead to heart murmurs.
  • Bulldog: Bulldogs are at risk of developing both congenital and acquired heart conditions, resulting in murmurs.
  • Great Dane: Great Danes can suffer from aortic valve issues, contributing to heart murmurs.

Genetic Factors

The genetic makeup of these breeds plays a significant role in their susceptibility to heart murmurs. Responsible breeding practices and regular veterinary check-ups are vital for early detection and management of heart conditions in these high-risk breeds.

Treatment and Management

Treatment and management of heart murmurs in dogs are crucial steps in ensuring your pet's well-being and quality of life. The approach taken depends on the underlying cause and the severity of the murmur.


In many cases, medication can effectively manage heart murmurs and their associated symptoms. Common medications include:

  • Diuretics: These help reduce fluid buildup in the lungs, relieving coughing and breathing difficulties.
  • Ace Inhibitors: These drugs dilate blood vessels, reducing the workload on the heart and improving blood flow.
  • Beta-Blockers: These can help control irregular heart rhythms and decrease the heart's workload.
  • Vasodilators: They relax blood vessels and improve blood flow, reducing strain on the heart.
  • Anticoagulants: These may be prescribed to reduce the risk of blood clots, especially in cases of certain heart conditions.

Lifestyle Changes

Your veterinarian may recommend lifestyle modifications to support your dog's heart health:

  • Diet: A special diet may be prescribed to manage weight and reduce sodium intake, reducing the workload on the heart.
  • Exercise: Tailored exercise plans can help maintain your dog's overall fitness while preventing excessive strain on the heart.
  • Stress Reduction: Reducing stress and anxiety can be beneficial for dogs with heart conditions.
  • Weight Management: Maintaining a healthy weight is crucial, as obesity can exacerbate heart issues.

Surgical Intervention

In severe cases, surgical procedures may be necessary to correct structural defects or improve heart function. These procedures may include valve repair or replacement, as well as pacemaker implantation for certain arrhythmias.

Preventing Heart Murmurs

Preventing heart murmurs in dogs starts with proactive care and awareness. While some factors, like genetics, may be beyond your control, there are steps you can take to minimize the risk:

Healthy Diet and Exercise

A balanced diet and regular exercise are essential for maintaining your dog's overall health. A lean body weight reduces the risk of heart issues, so consult your veterinarian for dietary recommendations.

Regular Veterinary Check-ups

Routine veterinary visits are crucial for early detection of heart murmurs. Your veterinarian can monitor your dog's heart health and recommend appropriate preventive measures.

Living with a Dog with a Heart Murmur

If your beloved pet is diagnosed with a heart murmur, it's important to understand how to provide the best care and support:

Quality of Life

Focus on maintaining your dog's quality of life. This includes ensuring they have a comfortable living environment, a balanced diet, and appropriate exercise.

Support and Care

Emotional support is just as essential as physical care. Spend time with your dog, offer affection, and minimize stressors to enhance their well-being.

Prognosis and Long-Term Outlook

The prognosis for dogs with heart murmurs varies depending on the underlying cause and how early it's detected. With proper treatment and management, many dogs can lead fulfilling lives despite their heart condition.

Life Expectancy

The life expectancy of a dog with a heart murmur depends on factors like the cause, severity, and response to treatment. While some heart conditions are manageable for years, others may have a more limited outlook.

Quality of Life Considerations

Above all, prioritize your dog's quality of life. Regular veterinary check-ups, medication adherence, and a loving, supportive environment can significantly improve their long-term outlook.

When to Seek Immediate Veterinary Attention

Understanding when to seek immediate veterinary attention can be a matter of life or death for dogs with heart murmurs.


In conclusion, heart murmurs in dogs are a complex and potentially serious condition that requires prompt veterinary attention and ongoing care. By understanding the causes, symptoms, and treatment options, you can provide your beloved pet with the best possible chance for a healthy and happy life.

FAQs About Heart Murmurs in Dogs

Q1: What causes heart murmurs in dogs?

Heart murmurs in dogs can be caused by a variety of factors, including congenital heart defects, acquired heart diseases, and anemia.

Q2: Can heart murmurs in dogs be cured?

The cure for heart murmurs depends on the underlying cause and the severity of the condition. While some can be managed with medication and lifestyle changes, others may require surgery.

Q3: Are certain dog breeds more prone to heart murmurs?

Yes, certain breeds, such as Cavalier King Charles Spaniels and Boxers, are more genetically predisposed to heart murmurs.

Q4: How are heart murmurs in dogs diagnosed?

Veterinarians use physical examinations and diagnostic tests like echocardiograms and X-rays to diagnose and grade heart murmurs.

Q5: What can I do to prevent heart murmurs in my dog?

Preventing heart murmurs involves maintaining a healthy lifestyle for your dog, including a balanced diet, regular exercise, and routine veterinary check-ups.

In this comprehensive guide, we've covered everything you need to know about heart murmurs in dogs, from their causes and symptoms to diagnosis, treatment, and prevention. Your furry friend's heart health is essential, and by staying informed, you can ensure a happy and healthy life for your canine companion.