A heart murmur is characterized by abnormal heart sounds. They are common in dogs and are detected during routine checkups when a veterinarian listens to the heartbeat using a stethoscope.
Heart murmurs in dogs can be mild and difficult to detect or strong and loud enough for the veterinarian to feel when placing their hands on your dog’s chest. Various factors—including defective valves, congenital disorders, and anemia—can cause heart murmurs. Depending on the severity and underlying cause, a murmur may be harmless or a sign of heart disease.
In this article, we’ll go over types of heart murmurs, causes, and treatment options to better help you understand this condition.
What Are the Symptoms of Heart Murmurs in Dogs?
Heart murmurs themselves do not cause symptoms. Instead, symptoms arise from the underlying condition responsible for the murmur. These signs are often associated with heart disease or reduced heart function:
- Exercise intolerance
- Coughing
- Heavy breathing while resting
- Weight loss
- Pale or blue gums
- Poor growth
- Poor oral/dental health
- Decreased stamina
- Weakness, collapsing, or fainting
What Causes a Canine Heart Murmur?
Murmurs are caused by turbulent blood flow, which produces a whooshing sound when heart valves or structures are abnormal.
- Obstruction of a valve
- Abnormal valve shape or size
- Blood leaking backward through a valve that does not shut properly
- Abnormal openings between structures
These abnormalities may result from congenital defects, aging, infection, disease, or injury.
Congenital Heart Disorders
Congenital defects develop before birth and can cause structural abnormalities in the heart or blood vessels. Some puppies outgrow mild congenital murmurs, while others may require lifelong monitoring or treatment.
Types of Heart Disease in Dogs
Heart murmurs are categorized by cause and timing:
- Congenital heart murmurs: Present at birth; often soft and may resolve by 6 months.
- Acquired murmurs: Develop later in life from valve disease or cardiac muscle disorders.
- Systolic murmurs: Occur when the heart contracts.
- Diastolic murmurs: Occur when the heart relaxes; rare in dogs.
- Continuous murmurs: Occur throughout the entire heartbeat cycle.
- Innocent murmurs: Mild, harmless murmurs that usually disappear as puppies mature.
Heart Murmur Grades in Dogs
Murmurs are graded based on loudness and intensity:
- Grade I: Very soft; barely detectable.
- Grade II: Soft but easily heard.
- Grade III: Moderately loud; often associated with underlying disease.
- Grade IV: Loud; easily heard on both sides of the chest.
- Grade V: Very loud; vibration can be felt through the chest wall.
- Grade VI: Extremely loud; audible without placing the stethoscope directly on the chest.
After detecting a murmur, veterinarians typically recommend diagnostics such as X-rays, ECG, or echocardiograms to determine the underlying cause.
Veterinarian Treatment of Canine Heart Disorders
Treatment focuses on the underlying condition. Depending on the cause, your veterinarian may recommend:
- Medications to support heart function or reduce fluid buildup
- Specialized low-sodium diets
- Routine monitoring every 6 months
- Supportive care for dogs with advanced heart disease
Innocent murmurs in puppies generally resolve by 6 months but should be monitored regularly until they disappear.
The Bottom Line
Heart murmurs are fairly common in dogs and aren’t always a cause for alarm. However, some murmurs indicate underlying heart disease that requires veterinary care. Monitoring symptoms—such as coughing, fatigue, or trouble breathing—helps ensure your dog receives help early.
Frequently Asked Questions About Heart Murmur in Dogs
What causes a heart murmur in dogs?
Most murmurs are caused by turbulent blood flow, often due to valve issues, congenital defects, or heart disease.
Can puppies outgrow heart murmurs?
Yes. Many puppies with innocent murmurs outgrow them by 5–6 months of age.
Is a heart murmur in dogs serious?
It depends on the cause. Some murmurs are harmless, while others indicate heart disease requiring treatment.
How are heart murmurs diagnosed?
Diagnosis often includes a physical exam, X-rays, echocardiograms, and blood tests to identify the underlying condition.
Can heart murmurs in dogs be treated?
Treatment focuses on managing the underlying issue with medication, monitoring, and dietary adjustments.
