Grade Three Heart Murmur IN a Puppy

Last Updated on January 13, 2022 by Griselda M.

A heart murmur is a worrying term for both humans and dogs, but how serious is a grade three heart murmur in a puppy? Despite the most natural concerns, a heart murmur might be a completely harmless occurrence. It could, however, also be a sign of something serious.

In today’s article, we’ll be taking a very close look at heart murmurs, learning what they mean with both adults and puppies, and defining just how dangerous they really are!

Heart Murmur In Dogs

heart murmurs in puppies

Heart murmur is not only a medical condition common in humans but in dogs as well! However, just like with humans, not all murmurs are cause for concern. There are more serious and more harmless murmurs, with some of them actually being symptoms of something else.

A heart murmur is essentially a noise caused by a disturbance in the blood flow of the heart. When a veterinarian listens to your dog’s heart, they’ll be able to clearly hear the murmur if there is one! If your dog is suffering from a murmur, your vet will define what’s causing it and what grade it is. We’ll be talking about murmur grades later, but now let’s focus on the causes.

Typically, a lot of murmurs can be broken down into harmless murmurs, and they’ll often disappear on their own. These murmurs are often caused by regurgitant flow, obstruction in the blood flow, or abnormal blood vessels. However, there are a lot of other possible reasons behind a heart murmur and you shouldn’t jump to any conclusions.

Canine Heart Murmur Grades And Types

Veterinarians use different grades to define the cause and the seriousness of the murmur. Professionals grade these murmurs from one to six.

Grade I

These murmurs are the least serious out of all murmurs and they’re actually difficult to detect with a stethoscope (because they barely exist).

Grade II

This type of murmur is still very soft, but a vet can hear it through the stethoscope.

Grade III

These murmurs still aren’t too serious, but every murmur that can cause a serious problem is at least a grade III.

Grade IV

A vet can pick these murmurs up easily as they’re loud enough.

Grade V

This type of murmur is so strong, you can feel it with your hand.

Grade VI

The most severe type of heart murmur.

Vets typically differ from three types of heart murmurs in canines: systolic murmurs, diastolic murmurs, and continuous murmurs. Continuous murmurs occur throughout your dog’s whole heartbeat, while systolic murmurs occur when heart muscles contract. Diastolic is the opposite of systolic, as they occur when your dog’s heart muscles relax.

Causes Of Heart Murmurs

Regarding the cause of a heart murmur, it’s best to define it by type. Professionals insist that the most common heart murmurs are systolic murmurs. There are many different conditions that can cause a systolic heart murmur, with the most common ones being pulmonic stenosis and subaortic stenosis. However, anemia, hyperthyroidism, cardiomyopathy, mitral, and tricuspid heart failure also causes a systolic heart murmur.

This means that most heart murmurs are actually just symptoms of something entirely different!

There are also diastolic heart murmurs, but vets insist that they’re not common amongst dogs. It’s possible that there’s an aortic insufficiency if there’s a diastolic murmur, but these murmurs really are rare.

Lastly, there are continuous murmurs. A common cause for them is PDA, with aortic stenosis being another common cause.

Heart Murmur In A Puppy

The good news is if your puppy was recently diagnosed with a murmur – it’s likely nothing to be worried about. Puppies can develop soft heart murmurs (Grade III and lower) with no long-term consequences. These murmurs will usually go away on their own, which is why they’re also called “innocent murmurs”.

These murmurs can appear as early as six weeks of age, and they can last until your pup is half a year old!

However, it’s also possible for your puppy to develop a stronger murmur that lasts for a longer time. If this is the case, you should take your pup to a specialist. If there is a disease, it’s best to start treating it as early as possible.

It is likely, though, that heart murmurs in puppies are nothing to be worried about!

canine heart murmur grades

Diagnosing And Treating A Heart Murmur

The easiest and the simplest way to diagnose a heart murmur is by using a stethoscope. This way, your vet can easily determine the grade and the type of the murmur. This is crucial, as the murmur is most likely just a symptom of another medical issue. After defining exactly what the murmur is, your vet can diagnose the cause and start treating it.

If your dog is still a puppy, the murmur is most likely an innocent one and there’s no reason for worry.

However, if the murmur persists as a symptom of a more serious illness, your vet will need to treat your dog. This treatment depends mostly on the diagnosis, so assuming what the treatment will actually be is pointless.

Assuming that your dog is going to be okay most likely isn’t pointless. Most murmurs aren’t dangerous, especially not with puppies. Even though they can be difficult to understand, know that it’s best to diagnose the illness early on and let the professionals do their job. Most causes for heart murmurs are treatable and your dog will most likely be just fine, especially if it’s still a puppy!


In conclusion, heart murmurs in puppies are usually nothing to be worried about. They appear on their own and they’ll most likely disappear on their own. In adults, heart murmurs of grade III and above can be a symptom of something more serious that needs treatment. Your vet will listen to your dog’s heart to detect and define a heart murmur by its grade and type. The only way to treat a heart murmur is to treat the condition that’s causing it.

Luckily, most heart murmurs are treatable and your dog will likely be fine!

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