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What is My Dog’s Life Expectancy With a Heart Murmur? A Vet Weighs In

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veterinarian listening to a golden retriever's heart

Heart disease is an extremely common cause of dogs presenting to the emergency room. When older, small breed dogs are rushed in with difficulty breathing I become extremely concerned about congestive heart failure. This is a condition where the heart is pumping ineffectively and fluid will back up into the lungs and pulmonary edema develops. Rapid action must be taken to help the body eliminate the fluid with diuretics while providing oxygen to enhance ease of breathing. 

This article takes a closer look at life expectancy for dogs with heart murmurs. An overview of heart murmurs can be found here

Mitral valve disease is the most common cause of murmurs and heart failure in older dogs which is why it is the focus of this article. This condition is dreaded by owners who have dogs with heart disease. While it’s easy to feel hopeless, some interventions can be provided to help dogs with heart murmurs live a long and happy life. The key is to work closely with your family veterinarian and a veterinary cardiologist. 

How Will a Heart Murmur Affect My Dog’s Quality of Life?

veterinarian inspecting dog

Dogs with heart murmurs can live a long very normal life in the early stages of heart disease. Dogs with early stages of mitral valve disease may have no apparent clinical signs. As dogs progress to advanced stages of the disease, their cardiac function begins to decline. Clinical signs of this include:

  • weakness,
  • lethargy,
  • coughing,
  • exercise intolerance,
  • poor appetite,
  • weight loss, and
  • collapse.

In the end stages of the disease, dogs may develop abdominal distension and fluid build-up in their bellies. Dogs with later stages of disease should be exercise restricted and owners should be diligent to prevent stressful situations. 

How Serious is a Heart Murmur in Older Dogs?

Heart murmurs in dogs should always be taken very seriously as the most common cause is mitral valve disease. This condition is always progressive because it causes degenerative changes to the heart valves.

  • As the valves become more diseased, blood flow is impaired causing the left side of the heart to become larger and larger.
  • Dogs with cardiac enlargement are more likely to develop heart failure if left untreated. 

If your veterinarian has detected a heart murmur in your dog diagnostics should always be performed to determine the stage of heart disease. X-rays taken of the chest will determine if heart enlargement is present. If so, therapy is warranted with pimobendan. If there is no cardiac enlargement present, therapy is not necessary and radiographs should be evaluated every 6 months for screening. 

Impact to Life Expectancy Based on the Cause of Heart Murmurs

Life expectancy of dogs with heart murmurs will greatly depend on the disease causing their murmurs: there are many different causes of heart murmurs in dogs. For example, murmurs may be secondary to a disease of the valves of the heart, a congenital defect of the heart, or a disease of the heart muscle:

  • Mitral valve disease is the most common cardiac disease, especially in small-breed dogs.
  • Dilated cardiomyopathy is common in large breed dogs such as Great Danes or Dobermans.
  • There are also several congenital heart defects that can impact a dog’s life.

The table below summarizes the impact to life expectancy for dogs affected by these diseases:

Type of heart murmursImpact to life expectancy
Innocent heart murmur 
(No disease identified)
Most commonly noted in puppies. Likely little to no impact to life expectancy. Most will disappear by 6 months of age.
Mitral Valve DiseaseStage B1: Months to years without treatment required
Stage B2: Up to 3.3 years with treatment (2.1 years without treatment)
Stage C: Up to a year with treatment
Stage D: Short life expectancy even with treatment
Dilated CardiomyopathyDogs with dilated cardiomyopathy can develop progressive cardiac dilation and heart failure, shortening their lives. Many dogs will live up to 1-2 years. If heart disease is present, median survival time is 6 months. If there are concurrent arrhythmias, the survival time is shorter.
Aortic Stenosis A congenital defect causing narrowing of the aortic outflow tract. Mild disease rarely causes any problems. Moderate to severe aortic stenosis may increase risk of sudden death. Severely affected dogs have a median survival of 19 months.
Pulmonic StenosisA congenital defect causing narrowing of the pulmonic outflow tract. Mild disease rarely causes problems. Severe cases require intervention with balloon valvuloplasty. Dogs with severe disease have potential to pass away suddenly. Survival of dogs with severe disease is dependent on surgical intervention and success of the procedure.
Patent Ductus ArteriosusA heart defect where the vessel that closes at birth fails to do so. If left untreated, puppies will develop heart enlargement and progress to heart failure. Surgical treatment is indicated. Dogs can have a normal life expectancy if surgery is performed early in life before signs of heart failure develop.

What is the Life Expectancy and Survival Rate With and Without a Heart Murmur Treatment?

As we have seen, life expectancy of dogs with heart murmurs will greatly depend on the disease causing their murmurs. Let’s look at life expectancy for dogs with Mitral valve disease, the most common cause of heart murmurs. Life expectancy depends on the stage of the disease:

  • Dogs with stage B1 heart failure can live months to years without treatment.
  • Once the disease has progressed to stage B2, treatment is recommended to promote longevity and delay the progression of heart disease. The EPIC study has found that dogs who were treated with pimobendan lived on average 1,228 days (3.3 years) compared to dogs that received a placebo who only lived 766 days (2.1 years).
  • Dogs who enter Stage C disease will die without treatment. With treatment, these dogs can live for up to a year before succumbing to the disease.
  • Stage D disease is the end stage and many of these dogs may only live a short period with treatment. 

Can Dogs Survive a Heart Murmur Without Treatment?

Dogs can live for a long time without treatment for heart disease in the early stages. Murmurs are most often found incidentally during a routine veterinary visit and many dogs will have no evidence of cardiac enlargement. Treatment is not even indicated at this time. 

Dogs that have evidence of cardiac enlargement should receive treatment to delay the progression of congestive heart failure. If you elect not to begin treatment, your dog may be fine for weeks to months, but the progression of the disease is inevitable. 


WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]


Dogs with congestive heart failure require emergent medical therapy. Without treatment, they will die from pulmonary edema. Humane euthanasia is strongly recommended if owners do not wish to aggressively treat heart failure. 

How Can I Make My Dog’s Life Better When My Dog Has Heart Murmurs?

Dogs with heart murmurs can live happy lives. In the early stages of the disease, they can still have a normal lifestyle. Dogs with more advanced stages of mitral valve disease should only perform light exercise and live as stress-free as possible. Cardiac diets can be used for the extra benefit of reduced sodium intake and appropriate amounts of protein. Omega 3 fatty acids are a great supplement to give dogs with heart disease and have cardiac protective benefits. Otherwise, it is important to be diligent with their medication dosing and ensure dogs are on a strict regimen. 

Owners should develop a close relationship with their family veterinarian and a veterinary cardiologist. This will ensure the best care is provided to dogs with heart disease. Routine echocardiograms should be scheduled as directed by the cardiologist with adjustments made to medications as necessary. 

How Will the Vet Treat a Heart Murmur?

Luckily, there are many treatments for dogs with heart murmurs caused by mitral valve disease. Early in the course of disease, no treatment is needed. Beginning oral medications is not recommended until dogs reach Stage B2 of heart disease. Stage B2 means that there is a murmur present and evidence of heart enlargement on radiographs. Learn more about the stages of heart disease here

Once dogs are diagnosed with Stage B2 disease, the first-line treatment recommended is Pimobendan. This is a medication that is used to help promote heart contractility and is protective of the heart. The use of pimobendan improves clinical signs of heart disease as well as prolongs the lifespan of dogs with this condition. 

Dogs that progress to stage C disease have developed congestive heart failure. Once this condition is apparent, many dogs will need to be hospitalized until they are no longer in heart failure. Veterinarians will administer diuretics and provide oxygen therapy. Many dogs will need to be hospitalized for several days until their condition improves. Once dogs are no longer in heart failure your veterinarian will likely consider starting an ACE inhibitor like benazepril or enalapril for adjunctive therapy. Additional diuretics like spironolactone may also be considered. 

Stage D heart disease is considered the worst and means that these dogs are no longer responding to standard treatment of heart failure. They may require high doses of cardiac medications or changing diuretic therapy. This stage of heart failure is considered end stage. Fluid may begin to develop in other parts of the body and dogs may need routine abdominocentesis performed. This is when a veterinarian uses a needle to empty the abdominal cavity of fluid buildup. This is a palliative treatment used to make dogs more comfortable.

FAQs

Is a Heart Murmur a Death Sentence for a Dog?

A heart murmur is not a ‘death sentence’ but it is often caused by mitral valve disease, which is unfortunately always progressive and irreversible. Many dogs will die from this disease whereas others may pass from other underlying diseases.


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How Serious is a Heart Murmur in an Older Dog?

A heart murmur should always be taken seriously and investigated. Early diagnosis of the cause of the murmur can lead to intervention that may prolong life. I recommend an echocardiogram for any dog I diagnose with a heart murmur. 

How Quickly Does a Heart Murmur Progress in Dogs?

Cardiac disease does not have a set timeline for progression. Many dogs will progress over 6 months to a year which is why biannual echocardiograms are recommended. In later stages, heart disease may progress more quickly. 

Is Exercise Good for Dogs with Heart Murmurs?

Normal exercise is fine for dogs with early stages of disease and is often encouraged to maintain lean body weight. Dogs that have advanced heart disease or have gone into heart failure should not be strenuously exercised. Exercise can put undue strain on the heart and lungs, worsening clinical signs of heart disease. 

Are Heart Murmurs Common in Older Dogs?

Heart murmurs are extremely common in older dogs, especially in small breeds. 10% of dogs presented to veterinarians will have heart disease. 70% of dogs with heart disease will have mitral valve disease. 

Author

  • Dr. Simons is an Emergency and Critical Care resident veterinarian at 'Cornell University Veterinary Specialists', a 24/7 Emergency and Critical Care Facility in Connecticut (Practice Profile). She graduated with a Doctorate in Veterinary Medicine (DVM) from the Ontario Veterinary College in 2019.

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Disclaimer: This website's content is not meant to be a substitute for veterinary care, diagnosis, or treatment. Always consult with your veterinarian to determine the best course of action. Read More.

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