What Is a Heart Murmur in Dogs? Explained!

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Author: Jeanette Hampton

Penny was once an energetic puppy who loved to run and play fetch.⚽ She would hop around the yard chasing balls and squirrels for hours.

But as Penny grew older, she started getting tired more easily. The vet discovered Penny had a heart murmur which made it harder for her heart to pump blood.

Now Penny moves slower, taking frequent breaks to rest. She can only play fetch for a few minutes before losing her breath. Though she can’t be as active as she used to be, Penny still enjoys her daily walks and quality time with her caring family.✨

What Is a Heart Murmur in Dogs

So, you must be wondering “What is a heart murmur in Dogs?” A heart murmur is an extra or unusual sound heard between heartbeats. 💖

Blood flowing abnormally across the heart valves causes a heart murmur. This produces a whooshing or swishing sound instead of the normal “lub” and “dub” sounds. Let’s understand this phenomenon in detail and how can we help our dogs live a healthy life.

What Is a Heart Murmur in Dogs?

Murmurs are caused by turbulent blood flow within the heart. Most murmurs are harmless, but some can indicate problems with the heart valves or abnormalities in the structure of the heart.

When the heart’s valves do not open or close properly, blood flows unevenly through the heart. This turbulent blood flow creates vibrations and sounds called murmurs. A mild, innocent murmur causes no symptoms and needs no treatment[1].

But more serious murmurs can cause symptoms like fatigue and shortness of breath. Diagnosing the cause and severity of a murmur helps determine which treatment the dog needs. Regular checkups help monitor murmurs.

dog owner loving the dog
"Coughing, Weakness, collapsing, or fainting, Exercise intolerance, Reduced stamina, Heavy breathing while resting, and Weight loss are the common symptoms of heart murmur in dogs", says Malcolm Weir from VCA Hospitals.🩺

Causes of Heart Murmur in Dogs

Let’s look at the causes and understand them:

  • Leaky or abnormal heart valves: This allows blood to flow backwards in the heart, creating a turbulent flow that causes murmurs.
  • Abnormal structure of the heart: Defects present from birth like a hole in the heart wall can cause abnormal blood flow and murmurs.
  • Heart infection: Infections of the heart’s inner lining (endocarditis) can damage valves and cause murmurs. Low red blood cell count makes the blood thinner, flowing more turbulently through the heart.
Dogs at Risk: Toys and small breeds like Chihuahuas, Miniature Pinches, and Pomeranians are genetically prone to heart defects. Heart valves can deteriorate with age, becoming leaky and causing murmurs. Systemic diseases like cancer or hypothyroidism increase the risk.📈
What Is a Heart Murmur in Dogs

Abnormal heart sounds heard through a stethoscope can indicate a heart murmur. Helps identify enlargement or structural abnormalities of the heart.

An ultrasound of the heart shows detailed structure and blood flow to evaluate the murmur. Identify underlying causes like anaemia or infection contributing to the murmur.

Heart Murmur Grades

The higher the grade, the easier the murmur is to hear. Higher-grade murmurs usually mean the problem is more advanced. But even soft murmurs can indicate serious heart disease. Let’s see the grades[2]:

  • Grade I murmurs are very faint and hard to hear even with a stethoscope. The vet really has to listen closely in a quiet room.
  • Grade II murmurs are soft but can be heard with a stethoscope.🩺
  • Grade III murmurs are loud enough to hear easily on one side of the chest with a stethoscope.
  • Grade IV murmurs are loud on both sides of the chest when listening with a stethoscope.
  • Grade V murmurs are very loud. You can feel the vibration if you place your hand on the chest.
  • Grade VI murmurs are the loudest kind. You can feel the vibration through the chest wall without even using a stethoscope.

Treatment of Heart Murmur in Dogs

The treatment for heart murmurs in dogs depends on the cause, the grade, and the clinical signs of the dog. Some heart murmurs may not require any treatment but regular monitoring, while others may need medications,💊 surgery, or supportive care. ❤️‍🩹

small dog breed enjoying in the park

Medications can support how the heart pumps and extend a good quality of life. It is important to keep your dog slim and active and provide them with a high-caloric and tasty diet.

  • Mild, harmless murmurs may just need regular vet checks to monitor them.
  • Drugs that help the heart work more efficiently may be prescribed. Common ones are ACE inhibitors to open up blood vessels, or diuretics to reduce fluid buildup.
  • Low-sodium diets can minimize fluid retention and strain on the heart. Limiting intense activity and exercise helps take pressure off the heart.💖
  • If faulty heart valves or defects are causing the murmur, surgery may repair or replace them. Severe murmurs can lead to heart failure. Additional drugs, oxygen therapy or other care may be needed.

Recovery and Management of Heart Murmur

After diagnosis, dogs need ample rest. Exercise is restricted to let the heart heal and prevent the worsening of the condition. Drugs help to manage fluid buildup and improve heart function. They need that for the long term.

vet checking the dog for heart disease

Regular vet visits to monitor the murmur and adjust meds if needed. Annual exams or biannual senior dog exams. Bloodwork and chest x-rays to monitor heart enlargement and function. An echocardiogram may be done periodically.

Low-sodium nutritional food helps decrease fluid retention and strain on the heart. Excess weight worsens heart disease. Keeping the dog fit helps reduce symptoms. A calm environment and minimizing stressors can help reduce heart demands.


❔How Long Can a Dog Live With a Heart Murmur?

Many dogs live a long time after being diagnosed with a heart murmur, and some can even live years after being diagnosed with heart failure. If you have any questions or concerns about murmurs, please contact your veterinarian.

❔Can a Dog Recover From a Heart Murmur?

The prognosis ranges from excellent to grave, depending on the cause of the murmur. If the murmur is physiologic, no treatment is required and the prognosis is generally good to excellent. If the murmur is caused by extracardiac disease or a functional problem that can be treated, the murmur may resolve over time.

❔What Is a Heart Murmur in Dogs?

A heart murmur adds an extra sound to a heartbeat — introducing a whooshing noise that your veterinarian can hear when they listen to your dog’s heart. A murmur can be mild and barely detectable, or quite loud, and possibly even strong enough that your veterinarian can feel it when they put a hand on your dog’s chest.

❔How Can I Improve My Dog’s Heart Murmur?

There are some ways of treating cardiac disease apart from medical treatment. Some options include surgery, managing a high-caloric and tasty diet that can compensate for the dog’s weight loss and loss of appetite, and exercise.


In conclusion “What is a heart murmur in Dogs?” heart murmur can be a cause of concern to avoid any unfortunate event we must consult with the vet if we notice any sign of the disease.

Just like Penny your dog too can live a healthy and happy life with a heart murmur. With little attention and proper care, we can provide our dogs with a good life. So, go ahead and take that run with your dog while looking after them!💖


  1. Get a jump on heart murmurs. (2023, May 5). Cornell University College of Veterinary Medicine.
  2. Thomas, J., DVM. (2023, January 20). Heart murmurs in dogs. PetMD.
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Jeanette Hampton
Jeanette Hampton is a content writer at WWD and an expert on all things pets. She’s been writing pet blogs for over 5 years and knows everything there is to know about dogs. Jeanette enjoys writing about pet-related topics because she enjoys helping people learn more about their furry friends.

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