Understanding Heart Murmur in Dogs: Recognition, Diagnosis and Management

Your canine companion provides invaluable emotional support and physical health benefits to your life. Just as you care for your heart health, ensuring proper cardiovascular wellness for your dog is equally important. Dogs cannot verbally communicate discomfort or abnormalities in their bodies, which is why regular veterinary check-ups are crucial for detecting conditions like heart murmurs. Although a heart murmur diagnosis may sound alarming, many cases are manageable and don’t necessarily indicate serious disease. Understanding what heart murmurs are, recognizing potential symptoms, and knowing your treatment options will help you provide the best care for your furry friend.

What Causes Heart Murmurs in Dogs: Identifying Risk Factors

When a veterinarian listens to your dog’s heart using a stethoscope, they are attuned to two distinct sounds: the “lub” and “dub” of a healthy heartbeat. Occasionally, veterinarians detect an abnormal, extra sound occurring between these two normal beats. According to the University of Missouri Veterinary Health Center, this phenomenon is typically caused by turbulent blood flow moving irregularly through the heart chambers or valves.

Heart murmurs are characterized by several distinguishing features, including their timing (whether they occur continuously or intermittently), their intensity (how easily they can be detected), and their specific location within the heart. Not every heart murmur signals an underlying cardiac disorder. The Merck Veterinary Manual notes that “innocent murmurs can be detected in healthy puppies less than 6 months of age,” meaning some murmurs resolve naturally as the dog matures.

According to Dr. Kimberly Nelsen, D.V.M., area medical director for IndeVets, heart murmurs can be classified into two categories: congenital (present at birth) or acquired (developing over time). Multiple factors can contribute to the development of a heart murmur in dogs:

• Breed predisposition (particularly common in Chihuahuas and toy poodles)
• Systemic diseases such as anemia with low red blood cell counts
• Serious infections, including untreated dental disease
• Degenerative valve conditions, especially mitral valve disease
• Structural abnormalities such as a hole or septal defect in the heart
• Chamber narrowing or stenosis

Dr. Nelsen emphasizes that “the most common causes of heart murmurs are, by far, congenital and breed/age related,” highlighting that many murmurs may not require intervention if they remain stable.

Recognizing Symptoms and Warning Signs

In many instances, dogs with heart murmurs show no observable symptoms whatsoever. As Dr. Preston Turano, D.V.M., a spokesperson with Figo Pet Insurance, notes, most cases are identified incidentally during routine wellness examinations rather than through owner observation. Dr. Nelsen adds that “owners will typically not notice many symptoms or behaviors of a dog with a low-grade heart murmur, and these dogs often appear completely normal at home.”

However, if a heart murmur progresses into more serious cardiac disease, pet owners may begin to notice several warning signs:

• Labored or difficult breathing, especially during activity
• Reduced exercise tolerance or reluctance to engage in physical activity
• Persistent coughing or dry cough
• Loss of appetite or decreased interest in food
• Marked changes in energy levels, stamina, or overall vitality
• General weakness or lethargy
• Fainting or collapse episodes

Being vigilant about these symptoms allows for early intervention and better management outcomes.

Diagnostic Methods for Heart Murmur Detection

The only definitive way to diagnose a heart murmur is through a thorough physical examination conducted by a licensed veterinarian. During this examination, the veterinarian carefully listens to the heart with a stethoscope to detect any abnormal or unusual sounds. When abnormal sounds are identified, veterinarians typically refer the dog to a veterinary cardiologist for specialized evaluation and additional diagnostic testing.

A veterinary cardiologist performs a comprehensive assessment similar to a human cardiologist, often utilizing advanced diagnostic tools. The diagnostic workup may include:

Physical Examination and Complete History: The cardiologist reviews the dog’s full medical history and performs a detailed physical examination, potentially including assessment of the mouth, eyes, jugular veins, heartbeat rhythm, and peripheral pulses.

Blood Pressure Measurement: While high blood pressure is uncommon in dogs, it can develop in conjunction with other medical conditions such as kidney disease, thyroid dysfunction, or adrenal gland disorders.

Resting ECG/EKG: This test evaluates the heart’s electrical activity and rhythm, identifying any abnormal heartbeats or electrical disturbances.

Ambulatory ECG Monitoring: A portable ECG recorder monitors the dog’s heart over 24 to 48 hours, capturing the frequency and characteristics of any irregular beats during normal daily activity.

Echocardiography: Ultrasound imaging creates detailed pictures of the heart chambers, valves, and major blood vessels, allowing assessment of the heart’s structure and mechanical function.

Cardiac Catheterization: In complex or severe cases, a thin catheter may be inserted into blood vessels to directly visualize the heart chambers and blood vessels with greater precision.

Treatment Options and Long-term Management

Treatment decisions depend on the severity grade of the murmur, underlying cause, and presence of clinical signs. Some dogs with mild, stable murmurs require no treatment beyond regular monitoring. Others benefit from specific interventions.

For dogs requiring treatment, management typically involves:

• Regular veterinary examinations (potentially multiple times annually)
• Prescribed cardiac medications to support heart function
• Specialized heart-supportive diets formulated for cardiac patients
• Periodic blood work and cardiac imaging to monitor disease progression
• Activity modification to reduce cardiac strain
• Weight management to decrease heart workload

Understanding Prognosis and Life Expectancy for Dogs with Heart Murmur

The long-term outlook for dogs diagnosed with heart murmur varies significantly based on multiple factors. As Dr. Grant Little, D.V.M., an expert at JustAnswer.com, explains, “It depends on what type of heart murmur is present, the diseases associated with it, and the age of the pet.” Some older dogs develop murmurs that cause no clinical symptoms throughout their natural lifespan. Conversely, severe congenital murmurs left untreated can progress to acute heart failure within 3 to 6 months.

Dogs diagnosed with murmurs secondary to mitral valve disease often have a more favorable prognosis. According to Dr. Turano, “If diagnosed early with minimal clinical signs, most dogs can live long, happy lives with proper monitoring and treatment.” Early detection, combined with appropriate medical management and regular veterinary oversight, significantly improves quality of life and longevity.

Why Senior Dogs Are Prone to Heart Murmurs

Heart murmurs are particularly prevalent in senior dogs, particularly in small breed dogs. Dr. Dwight Alleyne, D.V.M., veterinary advisor at Better Pet, notes that “heart murmurs are more common in senior small breed dogs because they are commonly caused by degenerative changes that occur over time.” Cornell University College of Veterinary Medicine research indicates that murmurs often involve progressive degeneration of the mitral valve, one of the heart’s four valves.

Larger breed dogs also frequently develop murmurs, though often through a different mechanism—cardiomyopathy, a disease affecting the heart muscle itself. Age-related cardiovascular degeneration is a natural part of the aging process in dogs, similar to humans, making routine cardiac screening essential for senior pets.

Pet Insurance and Financial Considerations

The overall expense of managing a heart murmur varies significantly depending on geographic location, murmur severity and grade, underlying cause, and the extent of required intervention. In some instances, no treatment is necessary.

Typical costs associated with heart murmur management include:

• Veterinary examinations (potentially four or more annually): $40 to $85 per visit
• Cardiology specialist consultation (typically annually, though sometimes quarterly for complex cases): $400 to $1,000 per visit
• Daily medications (for moderate to high-grade murmurs): $50 to $150 per month
• Periodic blood work (twice yearly or every 2-3 months for medicated dogs): $50 to $350
• Cardiac diet formulations: varies by brand and portion requirements

Whether pet insurance covers heart murmur treatment depends on your specific policy terms and whether the diagnosis occurred before or after coverage inception. According to Dr. Alleyne, “Pet insurance policies tend to cover diseases that develop over time after the patient has been established with the insurance company.” However, some insurers exclude congenital heart conditions. Conversely, certain companies do offer coverage for pre-existing conditions, though typically with limitations. Pet owners should carefully review their specific policy language to understand coverage parameters.

Ultimately, understanding heart murmur in dogs—from initial recognition through long-term management—empowers you to work effectively with your veterinary team to ensure your beloved pet receives optimal cardiac care throughout their life.