10 Must Know Things About Heart Murmur In Dogs

    Ever saw your dog get agitated and decided to find out what is troubling them and took them to the vet, only to find out about the heart murmur in dogs? Well, you need not worry if you have not heard that term before as this article explains all about this health issue in dogs in detail.

    You should know that a dog’s heart is not very different from a human’s heart. Both of our hearts function in a very similar fashion and that is the reason why dogs sometimes experience health issues related to the heart as well and heart murmur in dogs is just an example of that.

    You as an owner of the dog, might not be able to tell that your dog has heart murmur issues. If you feel something is bothering your pet then you can just take it to the vet and they will tell you what the issue behind your dog’s discomfort actually is. They will also negate any doubts relating to heart murmur in dogs for you if you have any.

    Even if you do not know anything about heart murmur in dogs, I am sure you would know how important hearts are to any living being. So if you find out that your dog has a heart murmur, it is valid for you to be a bit concerned.

    What you should keep in mind under such circumstances is that the heart murmur in dogs is of various types. Some of these types are very treatable as well whereas the others can be severe.

    In this article, I am going to be telling you everything there is to know about heart murmur in dogs, what they are, all their types, their symptoms, the grading system, the causes, their diagnosis and treatment, and a lot of other things. This is going to be a heavy ride, so hold fast and let us get started.

    What Is Heart Murmur In Dogs?

    Heart murmur in dogs is a rare condition. I am sure you know that our bodies use the heart to pump blood in our body and if you try to listen to your own heartbeat or someone else’s heartbeat, you will find that it is a constant rhythm.

    If somehow this rhythm gets disturbed or changes, the change is noticeable in the way the heart makes a sound. This sound is called a murmur and if you use a stethoscope to listen to it, you can easily tell which is the normal heartbeat and which is the murmuring.


    You can even call the heart murmur in dogs an extra vibration of the heart that causes a sound because the blood flow is disturbed.

    You should talk to the vet if your dog has a heart murmuring. They will tell you how to deal with it if it is a cause for panic, what kind of treatment it would require, the causes and all of the things that are relevant to heart murmur in dogs.

    Your vet would also tell you that heart murmur in dogs are classified into types or grades based on what they are. So let us now talk about the types of heart murmurs in dogs or their grade and configuration.

    Types Of Heart Murmur In Dogs


    There are a few different types of heart murmur in dogs. Mainly they are systolic, diastolic, and continuous. They are segregated into different types because of their timings.

    Systolic Murmurs

    The systolic murmurs happen when the heart muscle contracts. Most of the heart murmurs are systolic and they take place during systole which is a heart cycle phase when the heart is contracting to pump the blood out to the body.

    Some of the most common causes of the heart murmur in dogs are pulmonic stenosis or subaortic stenosis, which narrow the blood vessels that obstruct the blood flow or a leaky mitral valve that is the valve between the left upper and left lower chambers of the heart.

    Other causes of Systolic murmurs are:

    • Hyperthyroidism
    • Heartworm disease
    • Anemia
    • Mitral and tricuspid heart failure
    • Endocarditis of the mitral and tricuspid valve
    • Cardiomyopathy
    • Aortic valve insufficiency
    • Systolic anterior mitral motion (SAM)
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    Diastolic Murmurs

    The diastolic murmurs happen when the heart muscle relaxes between the heartbeats. Diastolic murmurs are a lot rarer than systolic murmurs in dogs. They are associated with aortic insufficiency as well which can happen because of the aortic valves leaking because it does not close thoroughly.

    The causes of diastolic murmurs are:

    • The mitral valve stenosis
    • The tricuspid valve stenosis
    • The aortic valve endocarditis
    • The pulmonic valve endocarditis

    Continuous Murmurs

    When it comes to the continuous murmurs, the name explains it all, it happens throughout the dog’s heartbeat cycle. This could be very easily determined.

    The causes of Continuous murmurs are:

    • Patent ductus arteriosus (PDA)
    • Aortic regurgitation caused by a ventricular septal defect
    • Aortic stenosis with aortic regurgitation

    A heart murmur can mostly be caused by the turbulent flow of the blood in the heart. Sometimes, these murmurs can be called innocent or physiological and sometimes they can be pathological or caused by a disease.

    The pathological murmurs can be caused because of cardiac diseases i.e. health issues that are related to the heart or they can be caused by extracardiac diseases, i.e. health issues not related to the heart. We will discuss everything about these things in this article as well, so stick around till then.

    The main types of causes of the heart murmur in dogs can be divided into three categories, which are:

    • Blood flow disturbances caused by abnormal valves or vibrations.
    • Blood flow disturbances caused by a regurgitant flow.
    • Blood flow disturbances caused by obstruction, diseased valves or dilated vessels.

    If the vet can find out what kind of murmur your dog has, it will help in finding out the cause of the heart murmur in dogs. They will determine what the best course of action is based on the age of the dog, its breed, and the results of all the tests that they conduct.

    Innocent Or Physiologic Heart Murmurs

    To put it in simple words, the innocent or physiological heart murmur in dogs are those murmurs that cause no harm to your dogs. These murmurs will have absolutely no impact on your dog’s health conditions.

    Young puppies, especially those of the large breeds tend to get the innocent heart murmurs. This happens because of them growing very rapidly. These murmurs might appear around the age of 6 to 8 weeks for them.

    You should not be concerned about them as these murmurs will go away in just four to five months. The innocent murmurs are named so because they are benign. You might think that anything abnormal about the heart should be the cause of concern but that is not true in this case. You just have to give the innocent murmurs some time, they will go away on their own.

    These murmurs have a very low intensity, i.e. they are below the Grade 3 level of intenseness. The innocent murmurs do not have any signs or symptoms. You might be wondering what these grades are, so let us find out.

    Grades Of Heart Murmur In Dogs


    Apart from the main types depending on the time when the murmuring happens, they are also divided into grades on a scale of 1 to 6. This grading system determines the loudness of the heart murmur in dogs.

    A grade 1 murmur shows the softest murmur whereas a grade 6 murmur denotes the loudest murmuring. Veterinarians determine the grade of the heart murmur in dogs so that it can help them decide what to do and also tells them the cause.

    Let us see what this grading system is.


    Grade 1: As I said, the grade 1 murmur is the softest murmur. These are so soft that they are barely audible. These types of murmurs are not serious at all or the least serious.

    Grade 2: Grade 2 murmurs have a soft sound to them that is just a tiny bit louder than the grade 1 murmurs.

    Grade 3: These have an intermediate murmuring loudness and they can be present in more than one location. Most of the murmurs that are a cause of concern are either grade 3 or higher.

    Grade 4: Grade 4 murmurs range from moderate to intense levels of loudness and they can be heard from both sides of the chest.

    Grade 5: These murmurs are very loud and they can be heard even if the stethoscope barely touches the chest of the dog. If you just put your hand on the chest, you can feel the Grade 5 murmurings.

    Grade 6: These can be felt by just placing your hand on the chest.

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    Another way the heart murmurs in dogs are classified is based on the configurations.

    Heart Murmuring Configuration In Dogs

    The configuration of the heart determines the way a heart murmur is sounding and that is how this classification is done. Basically, there are a total of 4 types of configurations. These are plateau, crescendo-decrescendo, decrescendo and machinery. Configurations are also often called qualities.

    These Configurations are:

    Plateau Murmurs: These murmurs have a uniform or constant loudness and they get associated with any of the aortic valve’s insufficiency.

    Crescendo-Decrescendo Murmurs: These are like a rollercoaster, they’ll be high and then go low, as in their loudness. First, they get loud and then they go quiet and then loud again. These can be connected to the aortic and pulmonic stenosis conditions.

    Decrescendo Murmurs: These murmurs will start loudly but then they will go much quieter and they are commonly seen in the aortic valve insufficiency or ventricular septal defect conditions.

    Machinery Murmurs: These murmurs are also called continuous murmurs and like the type above, these are also constant murmurings. They get associated with the patent ductus arteriosus (PDA). The PDA is a congenital heart defect.

    If you are not a vet, it can get very difficult to keep track of all these things like the types or grades or configurations as there are a lot of names or information associated with everything. So if you feel like you are getting confused or whatever, just ask your vet to clarify everything for you.

    Symptoms Of Heart Murmur In Dogs


    As I said, a heart murmur in dogs is a break of the rhythm of the heartbeats, it can be called an extra vibration which causes a sound to originate, called the murmurs. Although sometimes it could be the cause of concern, most of the dogs who get this, do not need any kind of treatment and they even live long and healthy lives.

    The question arises though, how can you tell if your dog has heart murmurs? Because you are not a vet, you would not tell if they have this issue. Well to help determine whether your dog has heart murmurs, you can keep a lookout for the following symptoms:

    • Irregular heartbeats
    • Lack of energy
    • Lack of appetite
    • Always feeling tired
    • Severe or constant coughs
    • Collapsing or fainting
    • Excessive panting even when they are sleeping or resting
    • Gums or tongue getting bluish tinge to them
    • Severe water retention
    • Racing pulse

    Although all the above things are symptoms of heart murmur in dogs, they can sometimes be indicating something much worse or severe. You must take your dog to the vet as only they can determine what is going on with your dog.

    *(Note: This article is just to help you get information about the heart murmur in dogs, all the things mentioned here should in no way be taken as a way of curing or treating your dog, you should always listen to your vet. This article is being written as just an informative work and not a guide.)

    Cardiac Issues That Cause Heart Murmur In Dogs

    Heart murmur in dogs is caused due to certain issues in the heart. These issues are called cardiac issues. There are four chambers in the heart and valves separate the chambers from each other which circulate the blood flow.

    Certain issues can be formed in the heart valves which can be either the thickening of the valves or the valves becoming thin. It could also be because of a leak in the heart valve. The thickening or thinning of blood vessels could also happen. Sometimes a hole between the chambers or arteries can also form.

    All these things can lead to a heart murmur in dogs. All these issues could either be congenital or acquired, i.e. either they can be since birth or they can form over their lives. Some congenital diseases can be genetic as well in certain breeds.

    These genetic diseases can be subaortic stenosis or pulmonic stenosis and patent ductus arteriosus as well. There are other diseases that might not be hereditary and these include ventricular septal defects, atrial septal defects, tetralogy of Fallot, etc.

    One of the most common causes of acquired heart disease is mitral insufficiency, which is also known as mitral regurgitation, which is when the mitral valves become thick and begin leaking. Mitral insufficiency is more common in dog breeds that are smaller in size.

    There are some other causes of acquired heart diseases as well and these happen in older dogs. These causes are bacterial endocarditis, which is caused by a bacterial infection that localizes on a heart valve as well as because of dilated cardiomyopathy. So all these diseases can be a reason for a heart murmur in dogs.

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    Extracardiac Issues That Cause Heart Murmur In Dogs

    As I already mentioned, besides issues that cause heart murmur in dogs, i.e. the issues that originate from the heart, there are other things that cause these murmurs as well. Issues that are not originating from the heart i.e. extracardiac issues are called functional heart murmurs.

    Functional heart murmurs can happen due to anemia, which is the presence of low levels of red blood cells or hypoproteinemia, which is the low amount of protein in the blood or because of fever or infection or other conditions like obesity or emaciation or even because of pregnancy.

    If murmurs happen because of anemia or hypoproteinemia can be caused because of heavy infestation of parasites like the intestinal worms or blood parasites and fleas and ticks. Adult dogs are more prone to anemia because of blood loss or certain other health issues that are very serious.

    Diagnosing Heart Murmur In Dogs

    Heart murmur in dogs is usually diagnosed using stethoscopes. The vet would listen to the chest of your dog and on the basis of what they hear, they will determine what kind of murmur your dog has. This would be done on the basis of the loudness or the murmur and the location of the murmur. Basically, on the type, grade, and configuration of the murmur.

    After they have determined the type of murmurs, they will then proceed to try and find out the cause of it. They will do this by doing a certain check and asking you questions about your dog’s health and other things. The age and breed of the dog would also help them in the process.


    Some issues and conditions like heartworm diseases can make your dog vulnerable to heart problems. Some dog breeds are also more likely to get heart diseases or abnormalities as well. These things could be genetic. Like I said before, young dogs could have innocent murmurs but adult dogs have an underlying cause for their murmuring and those require medical attention.

    To find out what the underlying cause might be, the vet will carry out more tests like radiographs, echocardiographs, electrocardiographs, etc. More tests could be suggested after that based on their results like blood tests or urine tests. Another thing that could indicate underlying problems are abnormal rhythmic heartbeats or weak or irregular pulses.

    Once all these things get clear, they can go on determined what kind of treatment your dog would require. If your dog is young and it is having the murmuring issue then the vet will just ask you to come back after some time to see whether it was an innocent murmur or not based on the increase or decrease in its intensity.

    The vet will call you back for a reexamination for your adult dog if the dog seems to be agitated but the murmuring is of low intensity. Sometimes it gets difficult to determine the murmuring because the dog is very excited and is panting heavily so it is essential that they remain calm.

    Dogs that have a poor appetite or have experienced weight loss or had a stunted growth as puppies or have difficulty in breathing and other such things are more prone to murmuring as these are some of the symptoms of heart murmur in dogs.

    Treatment Of Heart Murmur In Dogs

    Not all heart murmur in dogs require treatment. Innocent murmurs or physiological murmurs are completely harmless and they go away in some time. If your dog has an innocent murmur, you just need to keep on checking them to make sure no other conditions develop.

    The treatment of murmurs that are caused by underlying problems would be determined by the tests the vet runs. Some of these treatments might include specialized diets, medications, supportive care, etc. Congenital heart issues can be solved by surgery. These would include pulmonic stenosis and patent ductus arteriosus.

    Treatment for different things is different. The heartworm treatment would be completely different from congestive heart failure, so you should just listen to what your vet is advising as they know the best.


    Heart murmur in dogs is a complicated thing. But what you should keep in mind that you should not start panicking the moment you realize what it is. You should just follow all the instructions that your vet is giving you.

    Taking the utmost care of your dog will be very essential to the process of them healing and getting faster. The more you help your dog, the better it will be for them. So just keep that in mind and your dog would be all healthy and happy in no time.


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