Heart Murmur In Dogs Causes Prognosis

Veterinarians can detect anomalous cardiac sounds called heart murmurs by using a stethoscope to listen. Dog heart murmur can have many different origins, and the results might vary from having no effect on your dog’s health to having a more dire prognosis.

Dog owners may have concerns about heart murmurs because they could be signs of underlying medical conditions.

This enlightening article will address the origins of cardiac murmurs in dogs, as well as their symptoms and indicators. It will also offer insights into the diagnosis and various treatments. So, let’s know about heart murmurs in dogs causes prognosis.

What Is Heart Murmur In Dogs?

Dog anatomy is comparable to human anatomy in that blood is circulated throughout the body by the heart. The four chambers of the heart two ventricles and two atria are used for this.

To guarantee that blood flows in the proper direction, a one-way valve between each of these chambers opens and closes as blood fills and then empties out of each one. This is the reason behind the distinctive “lub-dub” sound of the heartbeat.

When the heart’s blood flow is turbulent, a heart murmur happens. Certain murmurs, particularly those heard in small puppies, maybe “physiologic” or “innocent,” meaning they won’t harm your dog’s health in any way. Innocent heart murmur in young puppies typically cause them to outgrow them by approximately five months.

An older dog’s heart murmur is less likely to be considered ‘innocent’ and may usually be classified as extracardiac (not caused by heart disease) or pathologic (caused by heart disease).

Grades Of Heart Murmurs In Dogs:

A similar scale is used to assess dogs heart murmurs, with 1 denoting the softest and hardest to hear and 6 denoting the loudest. When diagnosing the reason for the murmur and, if required, the appropriate course of action, veterinarians employ the number scale.

Here is a summary of the several grades that represent the severity of a dog’s heart murmur condition on a scale from one to six. See below these six grades.

Grade 1 Heart Murmurs:

At this point, murmurs are typically very faint, hardly perceptible. Generally speaking, these murmurs are innocuous and shouldn’t cause too much anxiety. Usually, they don’t need to be treated right away.

Grade 2 Heart Murmurs:

This grade of murmurs is characterized by quieter-than-usual tones and is yet considered reasonably innocuous. In most circumstances, close observation may be sufficient, and immediate treatment may not be required.

Grade 3 Heart Murmurs:

Heart murmurs become more noticeable at this point and can be heard more clearly through the use of a stethoscope. Although Grade 3 murmurs suggest a more obvious problem, not all of them need quick attention. Nonetheless, more research is advised to ascertain the best course of action.

Grade 4 Heart Murmurs:

As you go on, murmurs get louder and more mild. This is frequently an indication of a serious irregularity in the heart’s operation. In order to address the underlying problem and avoid potential complications, veterinary intervention and treatment are often recommended.

Grade 5 Heart Murmurs:

At this point, murmurs are extremely loud and audible even without a stethoscope. For an accurate diagnosis and prompt treatment, a veterinarian should be consulted immediately regarding these sounds. The increased severity points to a more serious cardiac issue.

Grade 6 Heart Murmurs:

Murmurs in degree 6, the most severe degree, are very loud and audible even without a stethoscope. This suggests a serious illness that needs to be treated right now. In order to address the serious impact on the dog’s cardiovascular condition, emergency veterinarian care is required.

What Are The Signs Of Heart Murmur in Dogs?

A heart murmur is an additional heart vibration that occurs when there is an irregularity in blood flow, producing an unusual sound. The noticeable noise is one that a medical professional can hear with a stethoscope and that can be distinguished from a normal heartbeat.

A murmur from your dog does not necessarily mean that you should become alarmed. Consult your veterinarian about heart disease and its potential consequences for your dog in the event of a more serious issue. Numerous dogs with cardiac murmurs go on to lead long, robust lives without ever needing medical intervention. Among the symptoms are:

  • Irregular heartbeat
  • Excessive panting even when resting
  • Collapses or faints
  • Tires easily
  • Hacking, persistent cough
  • Severe water retention
  • Lack of energy
  • Lack of appetite
  • Racing pulse
  • Gums and/or tongue are bluish in color

Not always a heart murmur, these symptoms could also be a sign of a more significant health issue. If your dog is showing any of these symptoms, only your veterinarian can diagnose the precise condition.

Types Of Heart Murmurs in Dogs:

There are three categories of heart murmurs: diastolic, systolic, and continuous. See below about these three types of heart murmur in dogs.

Systolic Murmur:

The majority of heart murmurs are systolic, meaning they happen when the heart is contracting to push blood out during the systole phase of the cardiac cycle. The valve that separates the left upper and lower chambers of the heart, the mitral valve, is most frequently the source of this murmur. Systolic murmurs are less frequently caused by pulmonic stenosis or subaortic stenosis, which are conditions where the blood artery narrows and obstructs blood flow.

Diastolic Murmur:

In dogs, this kind of murmur is unusual. Aortic insufficiency is the most common condition linked to this kind of murmur. It happens when the aortic valve leaks because it doesn’t seal tightly enough.

Continuous Murmur:

The most common cause of this kind of murmur is patent ductus arteriosus (PDA), which is the inability of the ductus arteriosus, a large blood artery, to shut down soon after birth. In dogs, it is the most common congenital abnormality.

What Is The Prognosis Of Heart Murder in Dogs?

Heart murmur prognoses vary from favorable to severe and are primarily dependent on the underlying etiology of the murmur. The prognosis for benign murmurs that don’t need to be treated is typically favorable to excellent. Over time, heart murmurs resulting from extracardiac illness or a treatable functional issue may go away.

Long-term treatment can help prolong or improve the quality of life for dogs with a leaky mitral valve. The prognosis for dogs with dilated cardiomyopathy varies, but it is generally not good if the dog is already exhibiting heart failure symptoms.

The prognosis varies for dogs with congenital cardiac abnormalities, although it is typically extremely excellent if surgery can correct the issue.

What Are The Causes of Heart Murmurs In Dogs?

Dogs may develop a cardiac murmur due to a variety of illnesses and disorders. Small dogs with heart murmurs are typically suffering from a leaky mitral valve, which is the heart valve that sits between the left atrium and left ventricle.

Blood can move from the left atrium to the left ventricle through the mitral valve, but it cannot return the other way. A dog’s valve may occasionally deteriorate with age, allowing blood to seep backward. Endocarditis, degenerative mitral valve disease, and chronic valve disease are some names for this illness.

Heart murmurs in larger breed dogs are sometimes brought on by a condition known as dilated cardiomyopathy, which can lead to a leaking mitral valve. A condition known as dilated cardiomyopathy weakens the muscles in the heart’s pumping chamber, reducing the heart’s ability to contract force.

Although these are frequently the causes of heart murmurs, a variety of other problems can also result in a murmur. In order to correctly examine your pet’s heart and identify the source of the heart murmur, your veterinarian can perform the necessary diagnostic procedures.

Birth Defects:

An abnormal development of the heart and surrounding blood arteries prior to birth may cause a cardiac murmur. These birth defects may result in an additional blood vessel, a cardiac hole, or a blood vessel narrowing.

The Patent Ductus Arteriosus (PDA) represents an extravascular bed. During a puppy’s pregnancy, an artery called the ductus arteriosus bypasses the lungs. Upon the puppy’s birth, the vessel ought to shut. Sometimes, though, it doesn’t.

Pulmonary stenosis, in which the pulmonic valve partially obstructs blood flow from the heart to the lungs, is another instance of a congenital illness. These illnesses have the potential to be fatal if treatment is delayed when they are severe.

Leaky Heart Valve: 

The left and right ventricles, as well as the atria, make up the four chambers of a dog’s heart. There are valves in between these chambers that open and close to allow blood to pass through the heart normally. Dog heart murmurs are most frequently caused by leaking heart valves.


Anywhere in the heart, a tumor can disrupt blood flow and produce a murmur.

Heart Muscle Disease: 

The most common cause of this in dogs is a weakening of the walls of the heart muscle, which causes turbulent blood flow and a murmur. Breeds like Dobermans, Boxers, and Giant Breed Dogs are susceptible to this illness.

Congenital Heart Defects:

Heart murmurs in dogs can be caused by a wide range of congenital cardiac abnormalities. Aortic valve stenosis (narrowing), which may be seen in breeds like Golden Retrievers and Rottweilers, pulmonic valve stenosis (narrowing), which is frequently seen in English Bulldogs, and patent ductus arteries (PDA), which is seen in many breeds including German Shepherds, Maltese, poodles, and Yorkshire Terriers.

Changes In The Size of the Heart:

The blood flow becomes less smooth and more turbulent as the heart enlarges. Though they don’t usually result, murmurs can result from this. Dogs with Dilated Cardiomyopathy (DCM) have enlarged hearts and thinned muscle walls.

Among other breeds, Dobermans and Cocker Spaniels are susceptible to this illness, which is regrettably sometimes fatal.

Recall that DCM does not always result in a cardiac murmur, which is why dog breeds that are predisposed to the illness should have screening for it.

Diagnosing a Heart Murmur in Dogs:

Be ready for further testing if your dog’s veterinarian listens to his heart and detects a murmur. An X-ray of the chest is the most typical test. This may help with a diagnosis by enabling your veterinarian to examine your dog’s heart, lungs, and pulmonary arteries.

However, the source of a heart murmur and the extent of the existing heart disease can only be determined by an echocardiogram or cardiac ultrasound. Depending on your dog’s specific situation, more tests might be suggested.

These include blood testing (heartworm test, complete blood count, and internal organ function screen), blood pressure monitoring, and an electrocardiogram (ECG) to measure your dog’s heart’s electrical activity.

Treating a Heart Murmur in Dogs

The cause of the murmur and whether it is having a detrimental effect on your dog’s life will determine how to treat a dog’s cardiac murmur. In the event that your dog exhibits no symptoms of cardiac disease, medication may not be necessary.

Every few months, your dog’s veterinarian may decide to watch them and only treat them if they see any clinical symptoms.

Surgery will be advised if the cardiac murmur in your dog is the result of a problem that can be fixed surgically, like a PDA. Treatment options include treating anemia and heartworm disease if they are the cause of the cardiac murmur.

Medication is used to treat leaky heart valves so that the heart can pump blood more efficiently. Dogs with various types of heart disease can lead relatively normal lives provided they are aware of the warning symptoms (mentioned above), take their meds as directed, and consult a reliable veterinarian.

It doesn’t have to be frightening to learn that your dog has a heart murmur. Your veterinarian can often handle the problem for you or collaborate with you to optimize your dog’s health and well-being. It is your responsibility as the pet parent to keep up with veterinary care and to keep taking your animal friend in for regular checkups.

Recovery Of Heart Murmurs in Dogs:

There is a connection between a cardiac murmur and an underlying illness. Numerous of those reasons are curable, and the murmur might go away on its own in certain circumstances. The most crucial thing is to identify it early and start treating the illness right away.

Treatment affects the prognosis because a heart murmur is not always a disease. Regular examinations are necessary to assess a dog’s response to therapy and make sure the murmur hasn’t gotten louder or altered.


Heart murmurs can differ in kind and intensity. Some heart murmurs are totally “innocent,” and owners might not even be aware that their dog has one, despite the fact that they are typically brought on by an underlying illness or cardiac abnormality.

It’s best to have your dog examined by a veterinarian if you think it could have a cardiac murmur so you can address the underlying cause and assess the severity of the condition.

Aapt Dubey
Aapt Dubey

Aapt Dubey, a devoted canine enthusiast and experienced dog Owner, brings boundless passion to our team. With a heart full of love for our four-legged friends, Aapt is dedicated to sharing insights on dog care, behavior, and training to make every pup's life happier and healthier at ItsAboutDog.com.

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