Heart Murmurs in Dogs: What They Mean & Diet Implications

Hearing your veterinarian say, "Your dog has a heart murmur," can be alarming. For many owners, it immediately raises questions:

Is my dog going to be okay?
Is a heart murmur the same as heart disease?
Does my dog need treatment?
Can nutrition make a difference?

The good news is that a heart murmur is not a diagnosis by itself. Some dogs live long, healthy lives with mild heart murmurs that never cause significant problems. Others may require monitoring, medication, or lifestyle adjustments depending on the underlying cause.

Understanding what a heart murmur means—and what it doesn't mean—is the first step toward making informed decisions for your dog's health.

In this guide, we'll cover:

What a heart murmur in dogs actually is
Common heart murmur symptoms
What causes heart murmurs
Treatment and management options
The role nutrition and healthy weight may play in long-term heart health

What Is a Heart Murmur in Dogs?

A heart murmur is an abnormal sound that a veterinarian hears while listening to a dog's heart with a stethoscope.

Normally, blood flows smoothly through the chambers and valves of the heart. A murmur occurs when blood flow becomes turbulent, creating a whooshing or swishing sound between heartbeats.

Quick Answer

A heart murmur in dogs is an abnormal sound caused by turbulent blood flow through the heart or blood vessels. It is a clinical finding, not a disease itself.

This distinction is important because a murmur can have many different causes—some harmless and some more serious.

Is a Heart Murmur the Same as Heart Disease?

No. A heart murmur is simply a finding that may indicate an underlying condition.

Some dogs with heart murmurs have:

Completely normal heart function
Mild age-related valve changes
Temporary physiological changes

Other dogs may have:

Valve disease
Congenital heart defects
Heart muscle disease
Other cardiovascular conditions

The murmur is often the clue that tells a veterinarian to investigate further.

How Veterinarians Grade Heart Murmurs

Veterinarians use a grading system to describe how loud a murmur sounds.

Grade

Description

Grade 1

Very soft, difficult to hear

Grade 2

Soft but consistently audible

Grade 3

Moderate intensity

Grade 4

Loud murmur

Grade 5

Very loud murmur

Grade 6

Extremely loud with a vibration that can often be felt

Important Insight

Many dog owners assume that a louder murmur automatically means more severe heart disease.

In reality, the cause of the murmur matters far more than the grade alone. Some loud murmurs may be associated with manageable conditions, while some softer murmurs can still indicate significant heart abnormalities.

Can Dogs Be Born With Heart Murmurs?

Yes, some puppies are born with congenital heart defects that create murmurs.

However, not every puppy murmur is cause for concern.

Many young puppies develop what's known as an innocent heart murmur, which often disappears as they grow and mature.

Your veterinarian may recommend monitoring or additional testing if a puppy murmur persists.

Heart Murmur in Dogs Symptoms

One of the most surprising things about heart murmurs is that many dogs show no symptoms at all.

In fact, countless heart murmurs are discovered during routine wellness exams long before owners notice anything unusual at home.

When symptoms do occur, they are usually related to the underlying heart condition rather than the murmur itself.

Common Heart Murmur Symptoms in Dogs

Dogs with significant heart disease may experience:

Reduced stamina
Exercise intolerance
Fatigue
Coughing
Rapid breathing
Difficulty breathing
Weakness
Decreased appetite
Fainting episodes

Some dogs develop symptoms gradually over months or even years.

Early Warning Signs Many Owners Miss

Heart disease often progresses slowly.

Before obvious symptoms appear, owners may notice subtle changes such as:

Taking shorter walks
Slowing down during play
Sleeping more frequently
Reluctance to climb stairs
Needing more recovery time after exercise
Less enthusiasm for activities they once enjoyed

These changes are often mistaken for normal aging when they may actually reflect declining cardiovascular function.

Signs That Require Prompt Veterinary Attention

Some symptoms should never be ignored.

Contact your veterinarian immediately if your dog develops:

Labored breathing
Persistent coughing
Collapse or fainting
Blue, gray, or pale gums
Severe weakness
Sudden exercise intolerance

These symptoms may indicate that the underlying heart condition has progressed and requires medical evaluation.

Important Insight Most Owners Don't Realize

Many dogs with early-stage heart disease appear completely normal.

A dog may:

Eat normally
Play normally
Maintain normal energy levels

while still having a detectable heart murmur.

This is one reason routine veterinary examinations are so valuable. Early detection often allows veterinarians to monitor changes before more serious symptoms develop.

Why Symptoms Can Vary So Much

Two dogs can have the same murmur grade but experience completely different outcomes.

Factors that influence symptoms include:

The underlying cause
Heart function
Age
Breed
Overall health
Disease progression

This is why diagnostic testing is often necessary after a murmur is discovered.

What Causes Heart Murmurs in Dogs?

A heart murmur is a symptom, not a disease.

To understand whether a murmur is concerning, veterinarians need to determine what is causing the abnormal blood flow inside the heart.

Some causes are relatively harmless, while others may require ongoing monitoring or treatment.

Mitral Valve Disease

Mitral valve disease is one of the most common causes of heart murmurs in adult and senior dogs.

The mitral valve sits between two chambers on the left side of the heart. Over time, the valve may begin to deteriorate and leak.

When this happens:

Blood flows backward
Turbulence develops
A murmur becomes audible

Small breeds are especially prone to mitral valve disease as they age.

Congenital Heart Defects

Some dogs are born with structural abnormalities of the heart.

Examples include:

Patent ductus arteriosus (PDA)
Pulmonic stenosis
Aortic stenosis
Septal defects

These conditions may create abnormal blood flow patterns that produce murmurs early in life.

Dilated Cardiomyopathy (DCM)

Dilated cardiomyopathy is a disease that affects the heart muscle itself.

As the heart enlarges and weakens, blood flow can become abnormal and murmurs may develop.

DCM is seen more commonly in certain large and giant breeds.

Heartworm Disease

Heartworms can damage the heart and blood vessels, particularly when infections become severe.

While not every dog with heartworms develops a murmur, advanced cases can contribute to cardiovascular abnormalities and heart-related symptoms.

Other Possible Causes

Additional causes of heart murmurs may include:

Anemia
Fever
Infection
High blood pressure
Changes in blood flow during growth
Certain metabolic conditions

These are sometimes referred to as "physiologic" or "functional" murmurs because they are not always caused by structural heart disease.

Not Every Heart Murmur Means Heart Disease

This is one of the biggest misconceptions among dog owners.

Some heart murmurs are:

Mild
Temporary
Clinically insignificant

Others may indicate:

Valve disease
Heart enlargement
Congenital abnormalities
Progressive cardiac conditions

The murmur itself does not determine the prognosis.

The underlying cause is what matters most.

How Do Veterinarians Diagnose the Cause of a Heart Murmur?

After detecting a murmur, your veterinarian may recommend additional testing to determine whether the heart is functioning normally.

This step is important because two dogs with similar murmurs may have completely different underlying conditions.

Physical Examination

The diagnostic process usually starts with a thorough physical exam.

Your veterinarian will evaluate:

Heart rate
Heart rhythm
Breathing patterns
Gum color
Overall cardiovascular health

The location and intensity of the murmur may also provide clues about its cause.

Chest X-Rays

Chest radiographs help veterinarians assess:

Heart size
Heart shape
Fluid buildup
Lung health

X-rays are often used to determine whether heart disease has progressed beyond the earliest stages.

Echocardiogram (Heart Ultrasound)

An echocardiogram is considered the gold standard for evaluating many heart murmurs.

This painless imaging test allows veterinarians to see:

Heart valves
Blood flow patterns
Chamber size
Heart muscle function

An echocardiogram often provides the clearest picture of what is causing the murmur.

Additional Testing

Depending on the situation, your veterinarian may also recommend:

Blood pressure measurement
Blood work
Heartworm testing
Electrocardiogram (ECG)

These tests help build a complete picture of your dog's cardiovascular health.

Important Insight About Diagnosis

One of the most reassuring things owners can hear is that a murmur was detected early.

Many heart conditions progress gradually, which means early identification may allow:

Better monitoring
Earlier intervention
Improved long-term management

Finding a murmur does not automatically mean your dog has serious heart disease, but it does provide an opportunity to learn more about their heart health before symptoms develop.

Heart Murmur in Dogs Treatment

One of the most common questions owners ask is:

"How do you treat a heart murmur in dogs?"

The answer depends entirely on the underlying cause.

Because a heart murmur is a finding rather than a disease itself, veterinarians focus on treating the condition responsible for the abnormal blood flow.

Some Dogs Need No Treatment

Many dogs with mild heart murmurs live normal lives without medication.

In these cases, your veterinarian may simply recommend:

Routine monitoring
Follow-up examinations
Periodic imaging
Tracking symptoms at home

Some murmurs remain stable for years without causing significant health problems.

Dogs With Heart Disease May Need Treatment

When heart disease is present, treatment may include:

Prescription medications
Blood pressure management
Fluid management
Activity recommendations
Ongoing monitoring

The treatment plan depends on the specific diagnosis and stage of disease.

Treatment Goals

The primary goals of treatment are to:

Improve quality of life
Reduce symptoms
Support heart function
Slow disease progression when possible

Many dogs continue to enjoy happy, active lives with proper veterinary care and management.

Important Insight Most Articles Skip

Heart health is not just about medications.

Long-term outcomes are often influenced by:

Weight management
Exercise habits
Nutrition
Early detection
Consistent veterinary care

This broader approach becomes especially important as dogs age or develop chronic cardiovascular conditions.

Can Diet Affect Heart Health in Dogs?

Diet cannot cure a structural heart condition or make a heart murmur disappear.

However, nutrition can play an important role in supporting overall cardiovascular health, maintaining a healthy weight, and helping dogs stay active and comfortable as they age.

This is one area where many dog owners can take a proactive approach after a heart murmur diagnosis.

What Nutrition Can and Cannot Do

It's important to set realistic expectations.

Nutrition cannot:

Reverse congenital heart defects
Repair damaged heart valves
Eliminate a heart murmur

Nutrition may help support:

Healthy body weight
Lean muscle maintenance
Energy levels
Overall cardiovascular wellness
Long-term quality of life

A heart murmur diagnosis often encourages owners to look more closely at their dog's overall health habits, including nutrition.

Why Healthy Weight Matters

Excess weight can place additional demands on the entire body.

Dogs carrying extra weight may experience:

Reduced stamina
Increased joint stress
Higher cardiovascular workload
Reduced mobility

Maintaining a healthy body condition is one of the most effective ways to support long-term wellness in dogs with chronic health conditions.

The Heart-Body Connection

Heart health doesn't exist in isolation.

A dog's cardiovascular system works alongside:

Muscles
Lungs
Metabolism
Immune system
Overall body condition

This is why veterinarians often emphasize a complete wellness approach rather than focusing only on the heart itself.

Important Insight Most Articles Miss

Many owners focus entirely on the murmur and forget about the bigger picture.

For dogs living with heart disease, daily habits often matter just as much as medications.

These habits include:

Maintaining a healthy weight
Regular veterinary monitoring
Consistent exercise recommendations
Balanced nutrition
Managing other chronic health conditions

Supporting overall health may help dogs maintain a better quality of life throughout the aging process.

Why Many Pet Parents Choose Spot & Tango

When owners learn their dog has a heart murmur, they often start paying closer attention to every aspect of their dog's health, especially nutrition.

Spot & Tango was built around the idea that dogs thrive on real food made from recognizable ingredients.

Their approach includes:

Personalized meal plans
Fresh, human-grade ingredients
UnKibble, a less processed dry food alternative
No artificial fillers or unnecessary additives

Many owners appreciate knowing exactly what goes into their dog's bowl, particularly when managing long-term health and wellness goals.

A Whole-Body Wellness Approach

Heart health is only one piece of the puzzle.

Dogs benefit from nutrition that supports:

Healthy weight management
Muscle maintenance
Digestive health
Immune function
Overall vitality

For dogs living with chronic conditions, many pet parents view nutrition as one part of a comprehensive wellness strategy alongside regular veterinary care.

Can Dogs Live a Long Life With a Heart Murmur?

In many cases, yes. A heart murmur diagnosis is not automatically a poor prognosis.

Some dogs live for many years with mild heart murmurs and never develop significant symptoms.

The outlook depends on several factors:

The underlying cause
Severity of the condition
Disease progression
Age
Overall health
Veterinary management

Factors That Influence Prognosis

Dogs tend to do best when:

Heart conditions are identified early
Follow-up monitoring is consistent
Symptoms are addressed promptly
Weight remains healthy
Overall wellness is prioritized

This is why routine veterinary visits remain so important after a murmur is discovered.

The Good News

One of the most reassuring things owners can hear is that many heart murmurs are manageable.

Even dogs with diagnosed heart disease can often enjoy:

Daily walks
Family activities
Playtime
Good quality of life

with appropriate veterinary care and monitoring.

FAQs About Heart Murmurs in Dogs

What is a heart murmur in dogs?

A heart murmur is an abnormal sound caused by turbulent blood flow within the heart or surrounding blood vessels. It is a clinical finding, not a disease itself.

Can a dog live with a heart murmur?

Yes. Many dogs live normal, happy lives with heart murmurs. The outcome depends on the underlying cause and whether heart disease is present.

What causes a heart murmur in dogs?

Common causes include:

Mitral valve disease
Congenital heart defects
Dilated cardiomyopathy
Heartworm disease
Anemia
Other conditions that affect blood flow

Is a heart murmur painful for dogs?

The murmur itself is not painful. However, the condition causing the murmur may eventually lead to symptoms that affect comfort, breathing, or energy levels.

Can diet help dogs with heart murmurs?

Diet cannot cure a heart murmur, but balanced nutrition may help support healthy weight, overall wellness, and quality of life.