Understanding Heart Murmurs In Canine Patients: A Complete Guide For Pet Owners

Having a dog enriches our lives in countless ways—from lowering our blood pressure to reducing cardiovascular stress. In return, we owe it to our companions to maintain their heart health. The challenge is that dogs cannot communicate their discomfort, which is why regular veterinary checkups are essential. During these visits, your vet may detect something called a heart murmur, an abnormal sound that develops within the cardiac cycle. While the diagnosis might sound alarming, understanding what it means and how to manage it can ease your worries.

Decoding The Cardiac Sound: What Actually Happens Inside Your Dog’s Chest

Your veterinarian listens for specific heart sounds during an examination—the characteristic “lub-dub” rhythm created by healthy valves closing. But sometimes an unexpected noise appears in between these normal sounds. The University of Missouri Veterinary Health Center identifies these interruptions as heart murmurs, typically resulting from irregular blood flow patterns through the heart chambers.

These abnormal cardiac sounds are classified by three defining features: timing (whether they occur constantly or sporadically), intensity (audibility level), and location (which part of the heart produces the sound). Not all murmurs indicate serious disease; in fact, the Merck Veterinary Manual confirms that healthy puppies under six months may display innocent murmurs that resolve naturally.

According to Dr. Kimberly Nelsen, D.V.M., a veterinary medical director with IndeVets, heart murmurs fall into two categories: congenital (present from birth) or acquired (developing over time). The most prevalent causes include breed predisposition—particularly in Chihuahuas and toy poodles—along with systemic conditions, severe infections like dental disease, mitral valve disease, cardiac structural abnormalities, or chamber narrowing.

When Should You Be Concerned? Recognizing The Clinical Signs

The tricky reality about many heart murmurs is their silence. Most dogs show absolutely no symptoms, and owners remain unaware their pet has any condition whatsoever. Dr. Preston Turano, D.V.M. and Figo Pet Insurance spokesperson, notes these discoveries typically happen during routine wellness appointments.

However, if a murmur progresses into genuine heart disease, pet parents may eventually observe behavioral changes: labored breathing, reluctance during exercise, persistent coughing, reduced appetite, unexplained energy loss, visible weakness, or fainting episodes. The absence of symptoms does not guarantee stability—gradual progression can occur without warning signs.

The Diagnostic Journey: How Veterinarians Identify Heart Murmurs In Dogs

A stethoscope examination remains the gold standard for initial detection. Your veterinarian will carefully listen for abnormal cardiac sounds, and if concerning findings emerge, a referral to a veterinary cardiologist becomes necessary.

The specialist conducts a comprehensive evaluation mirroring human cardiology practices. This may include:

Initial Assessment: A complete health history review combined with physical examination of the mouth, eyes, neck veins, heartbeat quality, and pulse characteristics.

Pressure Monitoring: While less common in dogs than humans, elevated blood pressure can accompany kidney disease, thyroid dysfunction, or adrenal conditions.

Resting Electrical Tracing (ECG/EKG): This test maps the heart’s electrical signals and detects irregular rhythms or abnormal electrical patterns.

Extended Heart Rate Monitoring: A portable recorder captures 24-48 hours of continuous cardiac data, revealing how frequently abnormal beats occur during daily activities.

Ultrasound Imaging (Echocardiography): Detailed sound wave pictures display the heart’s internal structure, valve function, and surrounding blood vessel conditions.

Advanced Catheterization: In complex cases, a thin tube navigates through blood vessels to directly visualize heart chambers and major vessels.

Understanding Heart Murmur In Dogs Stages And Severity Levels

Veterinarians grade murmurs on a numerical scale ranging from 1 to 6, with higher numbers indicating greater severity and clinical significance. This grading system helps determine appropriate monitoring frequency and treatment intensity. Lower-grade murmurs often require only periodic rechecks, while higher grades demand medication and dietary modifications.

Financial Reality: What Treatment Actually Costs

The expenses for managing a canine heart murmur vary based on geographic location, murmur classification, underlying cause, and required intervention intensity. Some murmurs need no treatment whatsoever.

According to Dr. Nelsen, typical costs include:

Veterinary Visits: $40-$85 per appointment (potentially four or more times annually)

Cardiology Consultation: $400-$1,000 per session (usually annually, sometimes quarterly)

Pharmaceutical Management: $50-$150 monthly for lifelong medication in moderate-to-severe cases

Laboratory Testing: $50-$350 for blood work (twice yearly or every 2-3 months for medicated dogs)

Therapeutic Nutrition: Prescription heart-supportive diets vary in price depending on brand and portion requirements

Pet insurance coverage depends entirely on individual policies and enrollment timing. Dr. Dwight Alleyne, D.V.M. at Better Pet, explains that most insurers cover conditions developing after coverage begins, though congenital cases may face exclusions. Some companies do accommodate pre-existing conditions with specific limitations.

Longevity Questions: How Will This Affect My Dog’s Lifespan?

Survival duration depends critically on murmur type, associated diseases, and the dog’s age at diagnosis. According to Dr. Grant Little, D.V.M., a JustAnswer veterinary expert, outcomes vary dramatically. Senior dogs may develop murmurs late in life with no clinical impact before natural death, while severe congenital murmurs left untreated could trigger acute heart failure within 3-6 months.

Dogs diagnosed with mitral valve disease-related murmurs generally have more favorable outlooks. “When identified early with minimal symptoms, most dogs enjoy long, fulfilling lives through consistent monitoring and appropriate care,” states Dr. Turano.

Why Older Dogs Face Higher Murmur Rates

Heart murmurs appear frequently in aging dogs, particularly smaller breeds. Dr. Alleyne explains this occurs because degenerative valve changes naturally accumulate over years, especially affecting the mitral valve. Larger dog breeds frequently develop murmurs related to cardiomyopathy, a progressive weakening of heart muscle tissue itself.

Understanding your dog’s cardiac health through informed conversations with your veterinarian transforms a concerning diagnosis into a manageable condition. Regular monitoring, appropriate medical intervention, and lifestyle adjustments can allow dogs with heart murmurs to continue living quality lives alongside their devoted owners.