Heart Murmur In Dogs: Symptoms, Causes, & Treatments

Vets examining greyhound with stethoscope on table in veterinary surgery

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Heart murmurs in dogs are extra vibrations or sounds in the heart that come from abnormal blood flow. A heart murmur is not a condition on its own, but rather a symptom of an underlying condition.

There is no direct treatment for heart murmurs in dogs, but the causes can often be treated, which may reduce the vibrations in the heart. Your veterinarian will find the cause of the heart murmur and then form a treatment plan.

Vets give heart murmurs in dogs a grade of I to VI. Grade I heart murmurs are barely audible, while grade VI murmurs can often be heard even without a stethoscope.

The grade doesn’t necessarily correlate to the severity of the underlying cause of the heart murmur. Vets also classify them based on the location of strongest intensity and the pattern that the vibrations follow.

These classifications, along with any other symptoms dogs have, help further narrow down the cause of the heart murmur, allowing vets to form a proper diagnosis and treatment plan. You must get to your vet if you see concerning symptoms in your dog.

Here’s what you should know about the symptoms, causes, and treatments associated with heart murmurs.

Symptoms Of Heart Murmur In Dogs

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Not all heart murmurs in dogs result in apparent symptoms. Some are completely benign and disappear with time.

However, many others are associated with heart disease. If you see the signs of heart disease accompanied by a heart murmur, then you must consult your vet immediately.

Here are a few signs of heart disease that may appear along with a heart murmur:

  • Exercise intolerance
  • Lethargy or weakness
  • Panting, coughing, or difficulty breathing
  • Pale gums or mucus
  • Distended abdomen or bloated appearance
  • Fainting or collapse

Causes of Heart Murmur In Dogs

LANDSHUT, GERMANY - MAY 13: Heard investigation of a dog on May 13, 2015 in Landshut, Germany. (Photo by Isa Foltin/Getty Images)

(Picture Credit: Isa Foltin/Getty Images)

Sometimes heart murmurs are benign, and dogs may just grow out of them. Other times, they can result from and indicate more serious medical conditions.

It’s common for young puppies to develop heart murmurs, though these are usually benign and known as physiologic heart murmurs. They occur when puppies, especially large breeds, grow quickly, and generally they disappear on their own after a few months. These cause no symptoms and aren’t a cause for concern.

Heart murmurs in dogs can be also caused by a variety of medical conditions. They can be congenital (present at birth), result from heart defects, or appear with infections, inflammation, or other diseases.

Here are a few of the conditions that can cause a heart murmur:

  • Endocardiosis
  • Endocarditis
  • Dysplasia
  • Cardiomyopathy
  • Atherosclerosis
  • Anemia
  • Heartworm
  • Hyperthyroidism
  • Valvular stenosis
  • Pulmonic stenosis
  • Tetralogy of Fallot
  • Tumors

Treatments For Heart Murmur In Dogs

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Vets don’t treat heart murmurs in dogs directly, as they’re not a condition on their own. But vets will address the underlying causes.

Treatment can vary greatly depending on the cause and severity of the condition. Physiologic heart murmurs in puppies often don’t require treatment, but puppies still need monitoring to make sure another condition doesn’t develop.

Simple dietary changes may treat mild heart murmurs.

Conditions that cause heart murmurs must be addressed by a veterinarian. In the case of heart defects, dogs may need surgery to correct the condition. Tumors may require chemotherapy. Vets may treat other issues with medication.

Your vet will develop a proper treatment plan after forming a diagnosis. It’s important to get regular check-ups, as vets often catch heart murmurs through routine vet visits.

Has your dog ever suffered from a heart murmur? What was the cause? Let us know in the comments below!