Heart Murmur in Dogs

A heart murmur in dogs can be an alarming discovery for pet owners, especially if it is diagnosed during a routine checkup. While the term “heart murmur” might sound serious, it is essential to understand what it means for your dog’s health. Heart murmurs are abnormal sounds heard during a heartbeat and can indicate underlying heart conditions or be harmless variations in blood flow. If your veterinarian has detected a heart murmur in your dog, you may have many questions about what this means and what steps to take next. Understanding the causes, symptoms, and potential implications of a heart murmur in dogs can help you feel more informed and prepared to support your pet’s health.

 

 

What is a Heart Murmur in Dogs?

A heart murmur in dogs is an abnormal sound that your veterinarian may hear when listening to a dog’s heartbeat with a stethoscope. The murmur is caused by turbulent blood flow within the heart or surrounding blood vessels. This can result from structural abnormalities, congenital heart defects, or other underlying health conditions. Heart murmurs are classified based on their intensity, location, and timing during the cardiac cycle.

Grades of Heart Murmurs

Veterinarians grade heart murmurs in dogs on a scale from I to VI, with grade I being the least severe and grade VI being the most pronounced.

• Grade I: Soft, intermittent heart murmur (not heard with every beat).
• Grade II: Soft heart murmur that is heard with every beat.
• Grade III: Moderately loud and commonly detected.
• Grade IV: Loud heart murmur that can be heard on both sides of the chest.
• Grade V: Very loud with a palpable vibration (thrill).

The severity of the heart murmur does not always indicate the severity of the underlying heart disease, so further testing is often needed.

What Causes a Heart Murmur in Dogs?

There are several potential causes of a heart murmur in dogs, ranging from benign conditions to serious heart diseases. Identifying the cause is crucial for determining the best course of action.

Innocent or Physiologic Murmurs

Some heart murmurs in dogs are considered “innocent” or “physiologic” and do not indicate heart disease. These murmurs are common in puppies and often resolve as they grow older. In some cases, adult dogs may have benign murmurs due to mild changes in blood flow that do not impact their overall health.

Congenital Heart Defects

Dogs can be born with congenital heart defects that cause murmurs. Some of the most common congenital conditions include:

• Patent Ductus Arteriosus (PDA): A blood vessel that remains open after birth.
• Pulmonic Stenosis: Narrowing of the pulmonary valve, restricting blood flow to the lungs.
• Subaortic Stenosis: Fibromuscular narrowing below the aortic valve, making it harder for blood to leave the heart.

Acquired Heart Conditions

Heart murmurs in dogs can also develop later in life due to acquired heart disease, including:

• Mitral Valve Disease (MVD): A degenerative condition affecting the mitral valve, commonly seen in small breed dogs.
• Dilated Cardiomyopathy (DCM): A disease that affects the heart muscle, leading to an enlarged heart and poor contraction ability.
• Heartworm Disease: A parasitic infection that can cause damage to the heart and lungs, leading to murmurs.

Diagnosing a Heart Murmur in Dogs

When your veterinarian detects a heart murmur in dogs, they will typically recommend further testing to determine the underlying cause and severity. Diagnostic tests may include:

• Echocardiogram: An ultrasound of the heart that provides detailed images of heart structure and function.
• X-rays: Chest radiographs can show the size and shape of the heart and detect fluid buildup in the lungs.
• Electrocardiogram (ECG): Measures the electrical activity of the heart to identify arrhythmias.
• Blood Tests: Can help detect infections, heartworm disease, or other systemic conditions that may affect heart function.
• Blood Pressure Measurement: High blood pressure can contribute to heart disease and requires monitoring.

Addressing Heart Murmurs in Dogs

The treatment for a heart murmur in dogs depends on its underlying cause. In cases of innocent murmurs, no treatment may be necessary, but regular checkups will help monitor any changes.

Medication

If a heart murmur is linked to heart disease, medications may be prescribed to manage symptoms and improve heart function. Common medications include:

• Diuretics to reduce fluid buildup in the lungs.
• ACE inhibitors to lower blood pressure and ease the heart’s workload.
• Beta-blockers to help regulate heart rate and rhythm.
• Pimobendan to strengthen the heart muscle and improve circulation.

Many of these medications are used to treat heart failure. There are times when medication may be recommended before heart failure and this is why it is important to determine the underlying cause of the disease.

Surgery or Interventions

For congenital heart defects like PDA or pulmonic stenosis, surgical procedures or catheter-based interventions may be recommended to correct the issue. There are a few surgical and palliative procedures that may be available and can be discussed with the cardiologist.

Lifestyle Management

Dogs with heart murmurs may benefit from certain lifestyle changes, such as maintaining a normal weight and regular exercise to maintain fitness without overexertion.

Is It Time to Call Your Veterinarian?

If your dog has been diagnosed with a heart murmur, it is important to work closely with your veterinarian to monitor their condition. At Pinnacle Veterinary Specialists, we provide advanced diagnostics and expert care for heart conditions in dogs. If you have concerns about a heart murmur in dogs or notice any worrisome symptoms, call (610) 477-8797 to schedule an appointment today. Early detection and professional care can make all the difference in maintaining your dog’s health and quality of life.