Heart Murmur in Dogs: Stages, Causes, And Diagnosis

heart murmur in dogs

Dogs are regarded as human’s closest pets because of their unique features, adaptation abilities, sensory capabilities, and physical features. They can be taught and modified to act in a particular manner. Like humans, dogs possess a well circulatory system that helps in the effective regulation of blood and nutrient, in which the heart serves as the pivot of the system. The heart in dog bodies helps to supply oxygen and nutrients to the right tissues, remove carbon dioxide and other wastes. But when a deficiency happens, it causes an obstruction in the circulatory process, and one of the most frequent heart problems among dogs is a heart murmur.

What is Heart Murmur?

Heart murmur in the easiest term can be explained as an obstruction in the flow of blood that creates an audible noise. A heart murmur is a recurring sound heard in the heart through a stethoscope. It usually signifies a sign of disease or damage. The noise heard in the heart is produced by a problem in the heart valve. One may be asking, does any sound from blood flow signifies murmur? No, not all sounds signify murmur, we have two types of sounds, “innocent and abnormal sounds”. Innocent sound isn’t dangerous and normally does not require medical intervention. Abnormal sounds signify an underlying problem or damage.

Stages of Heart Murmur

Heart murmurs are classified in grades. It ranks from grade I to grade VI as described below:

Grade I

Murmurs are barely audible. They can’t be detected with a stethoscope. These murmurs are the least serious.

Grade II

Murmurs are faint, but it can be heard with the aid of a stethoscope.

Grade III

The loudness of the murmur ranges between those of grades II and IV. This type of murmur and above can cause serious problems. Murmurs have intermediate loudness.

Grade IV

These murmurs are loud, and they can be heard. They radiate widely, often including opposite sides of the chest.

Grade V

The vibration can be felt by placing your palm on your dog’s chest. These murmurs are very loud and can be heard clearly with a stethoscope.

Grade VI

This is the most severe case of heart murmurs. Similar to grade V murmurs, grade VI murmurs are very loud and the vibration can be felt through the chest.

Life Expectancy of Dog Heart Murmurs

Grade III, IV, V, and VI life expectancy cannot be adequately calculated. Some dogs can live for some months, even years after being diagnosed with heart failure or disease. The life expectancy is dependent on the level of nutrition and treatment provided to your dog. This leads us to the symptoms, causes, and diagnosis of the heart murmur. When discovered early, the life expectancy of the animal may be prolonged.

Symptoms of Heart Murmur in Dogs

Chronic Coughing

The causes of coughing in dogs include infection caused by bacteria, viruses, parasite or heartworms. It’s normal for dogs to cough at times, but when it keeps reoccurring, you need to invite a licensed veterinarian for a checkup. Cough points out an underlying problem.

Difficulty in Breathing

This is also known as Dyspnea. Panting on a hot day, or after some exertion isn’t the same thing as difficulty in breathing. When a dog finds it difficult to breathe, you may notice some anxiety in the animal. You will notice the dog opening his mouth, trying to get some air. You will also notice that breathing might be noisy to some extent. 

Difficulty in breathing is a major indicator of heart murmurs, when you notice it, quickly take your dog to a qualified licensed veterinary for a checkup. 


Fainting in dog occurs when there is a sudden shift in the rhythm and movement of blood flow in the dog’s body. The shift, which can be either too slow or fast, can disrupt the circulatory process. Fainting itself isn’t bad, but it’s an indicator of an underlying problem.

Unusual weakness

The heart is charged with the responsibility of moving blood and vital nutrients to all organs of the body. But if the heart isn’t pumping one, the vital organs will be starved. This leads to the dog getting exhausted always.

Sudden weight gain or swelling

When the blood is not well disposed of by the dog’s body, this could lead to the accumulation of unwanted blood. This could result in swelling or weight gain. It serves as an indicator of a problem in the circulatory system.

Poor appetite

When the dog refuses to eat, and it becomes persistent. A check should be done to ascertain the cause.

Change in color

Skin, fingertips, and toes may appear grey, signifying a shortage of blood in those areas.

What is the Cause of Heart Murmurs in dogs

Having identified the symptoms in your pet dog, and the veterinary confirmed it to be a heart murmur, your question could be, “what caused it? Am I feeding it well? Does he sleep in a comfortable place?

Heart defects and blood flow obstruction can be a contributing factor that causes heart murmurs in dogs. The causes can, however, differ in terms of the breed, age, and health status of the dog. Whatever situation it may be, the causes aren’t far from us. Some of the causes include:

  • Abnormal vibrations that cause agitation
  • Agitation caused by regurgitating flow
  • The agitation that results from obstructed, diseased, or dilated vessels
  • Anemia
  • Aortic valve insufficiency
  • Cardiomyopathy
  • The endocarditis of the mitral and tricuspid valve
  • Hyperthyroidism
  • Mitral and tricuspid heart failure
  • Poisoning, which could be in the form of food Poisoning
  • Systolic anterior mitral motion (SAM)

How Can Heart Murmurs Be Diagnosed?

Usually, heart murmurs are diagnosed using a stethoscope. The veterinarian doctor listens to your dog’s heart. The loudness of the heart, the direction it’s coming from and some other factors will determine the grade of the heart murmur your dog possesses, either grade I, II, III, IV, V, or VI. After identifying the type and grade of the heart murmur, your vet doctor will then go on to diagnose the cause.

One of the ways the doctor pinpoints a probable cause is based on your pet’s age, breed, and overall health. Some particular diseases, like heartworm disease, can be found in some species of dogs. The treatment will be different than the one whose heart murmur was caused by Poisoning. The cause determines the treatment. 

Your veterinarian can assist in diagnosing any hidden cause. With the aid of echocardiograms, radiographs, and an electrocardiogram, the underlying cause can be detected. Depending on the veterinarian’s diagnosis, additional tests may be necessary.

Is there any medicine that helps in treating Heart Murmurs in Dogs?

Heart murmurs cannot be treated; only the symptoms and the causes can be treated. Because heart murmurs signify an underlying problem or defect in the dog’s system, its symptoms when observed, should be given due consideration. For example, Enalapril is a medication effective in treating dogs suffering from serious heart problems, caused by an obstruction in the blood flow resulting in Heart murmurs. It helps supply nutrients that help boost cardiovascular health in Dogs. 

Finally, there is no specific cure for heart murmurs; only symptoms and cause can be prevented and cured.