Dog Heart Murmur: Grades, Symptoms & Treatment Options

A heart murmur in a dog is an abnormal whooshing sound heard during a heartbeat, typically detected with a stethoscope. It indicates turbulent blood flow within the heart. The severity of the murmur is graded on a scale of 1 to 6, with 1 being the least severe and 6 being the most severe.

Heart Murmur Grades:

• Grade 1: Soft murmur, difficult to hear, and only audible in a quiet room. Often considered innocent, especially in young puppies.
• Grade 2: Soft murmur but easily heard with a stethoscope. May still be innocent or indicate a mild underlying issue.
• Grade 3: Moderate murmur, readily heard and louder than a Grade 2. Further investigation is usually recommended.
• Grade 4: Loud murmur that can be heard on either side of the chest. Usually associated with significant heart abnormalities.
• Grade 5: Very loud murmur that can be felt as a vibration (thrill) through the chest wall. Indicates severe heart disease.
• Grade 6: Extremely loud murmur, audible even without a stethoscope directly on the chest wall. Represents critical heart dysfunction.

Symptoms:

While some dogs with heart murmurs, especially low-grade ones, may show no symptoms, others can exhibit a range of signs depending on the severity of the underlying heart condition. Common symptoms include:

• Coughing, especially at night or after exercise
• Difficulty breathing or shortness of breath
• Exercise intolerance or fatigue
• Weakness or fainting spells (syncope)
• Bluish tinge to the gums or tongue (cyanosis)
• Swollen abdomen (ascites) due to fluid buildup
• Weight loss

It’s important to note that the absence of symptoms doesn’t necessarily mean the heart murmur is harmless. Some heart conditions can progress slowly without noticeable signs until the disease is advanced.

Diagnosis:

If your veterinarian detects a heart murmur, they will likely recommend further diagnostic tests to determine the cause and severity. These tests may include:

• Echocardiogram (ultrasound of the heart): Provides detailed images of the heart’s structure and function.
• Electrocardiogram (ECG): Records the electrical activity of the heart.
• Chest X-rays: Help assess the size and shape of the heart and lungs.
• Blood tests: Can rule out other medical conditions and assess kidney and liver function.

Treatment Options:

Treatment for a heart murmur depends on the underlying cause and severity of the condition. Some dogs with mild murmurs may not require any treatment, while others with more severe conditions may need medication and lifestyle adjustments. Treatment options can include:

• Medications: Such as diuretics (to reduce fluid buildup), ACE inhibitors (to lower blood pressure), and positive inotropes (to improve heart muscle contractility).
• Dietary changes: A low-sodium diet can help manage fluid retention.
• Exercise restriction: Limiting strenuous activity can reduce stress on the heart.
• Surgery: In some cases, surgery may be an option to correct heart defects.

Regular veterinary checkups and monitoring are crucial for dogs with heart murmurs to track the progression of the disease and adjust treatment as needed. Early diagnosis and appropriate management can help improve the dog’s quality of life and potentially prolong their lifespan.