Cardiovascular diseases

Heart Murmur in Dogs

Josie F. Turner
By Josie F. Turner, Journalist specialized in Animal Welfare. Updated: February 22, 2018
Heart Murmur in Dogs

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The average life of our animal companions has increased significantly thanks to the care we provide and advances in veterinary medicine. However, with the increase in life expectancy, we will have to learn to coexist with conditions that usually appear in geriatric animals.

Whether the vet has detected a heart problem in your dog, or you have just welcomed a dog to the family, we want you to be prepared to detect an irregularity as soon as possible. For this reason, AnimalWised proposes the following article on heart murmurs in dogs. We will detail the symptoms and treatment and what to expect after diagnosis.

You may also be interested in: Signs and Symptom of Heart Failure in Dogs


  1. What is a heart murmur?
  2. Chronic valvular disease (endocardiosis)
  3. Symptoms of chronic valvular disease
  4. Diagnosing chronic valvular disease
  5. Treatment of chronic valvular disease
  6. Non-pharmacological treatment

What is a heart murmur?

When we speak of murmur, we mean an abnormal sound detected in cardiac auscultation. Consider the heart and the great vessels that enter and leave it as a system of pipes. The murmur refers to the strange noise that is generated when the conduction of the blood through some of those pipes and keys of passage, finds some difficulty.

The veins and arteries in this case would be pipes, and the heart valves the stopcocks. Thus, if any of these pipes are obstructed (for example, if there is a clot in them), or one of the valves does not open or close properly, we will detect a non-physiological sound that is generally called a "murmur".

So when they tell us that our dog has a murmur, they are not making a diagnosis: the vet is saying that something is happening in the normal conduction of blood, some alteration that can be due to multiple causes and we have to undergo several studies to know what it is and which is the best treatment to follow.

Since it is impossible to cover all possible causes of murmurs without writing a cardiology treaty, we will focus on the type of murmurs that are most commonly detected in a veterinary clinic, almost always, during routine pre-vaccination annual examinations.

Heart Murmur in Dogs - What is a heart murmur?

Chronic valvular disease (endocardiosis)

The literal translation of these three words means chronic degeneration of the heart valves (mitral, triscuspid, aortic and pulmonary). These valves are formed by several components and the degeneration can affect all of them, or just a specific one in a special way.

For example, the valves, the part that could be called the valve door, may be affected by the formation of myxomas, cauliflower-like nodules, which prevent them from opening normally.

The valve is set on a fibrous ring. We could say that this is the frame of the door, which can also degenerate and there are many components that can suffer the same fate, although for different reasons. For example, the papillary muscles, which are inserted at the edge of the valves by tendon cords, when contracted and relaxed, open and close these valves.

When the valves cannot be closed properly, it is called "insufficiency". The blood projected to another chamber of the heart experiences a reflux when the gate does not close properly by which it goes through and this is what the stethoscope will detect. In the case of chronic valvular disease, that is precisely what happens. All the components of the valves, or some in particular, are not able to fulfill their mission, not allowing to seal a valve after the blood has been ejected through it.

Breeds prone to suffer chronic valvular disease

There are several dog breeds that are prone to suffer chronic valvular disease or endocardiosis in one of their valves (perhaps the most common in the mitral), but that does not mean that it is exclusive to them. The proportion of patients of these affected breeds is just higher than in any other. Some of these breeds are:

The average age when this disease occurs is 7-8 years of age, except in the King charles cavalier, that can be diagnosed from the age of 5 with relative frequency.

There has been much speculation as to the reason for this higher incidence in these breeds and it is believed that dyscolagenosis, a failure in the correct synthesis of genetic collagen, may be behind it. The collagen matrix is ​​fundamental throughout the valvular structure and these breeds are predisposed to severe periodontal diseases and alterations of their knee ligaments. These alterations, have a common denominator - collagen.

In general, if a murmur is detected when examining a dog that is more than 7 years old, that is small size (less than 10 kg or 22.04 lbs), a provisional diagnosis of chronic valvular endocardiosis can be made until the appropriate tests say otherwise. It is not frequent in cardiac pathologies, and many other factors have to be taken into account and some tests performed to confirm it.

Symptoms of chronic valvular disease

It is very common to be asymptomatic for months or years due to the compensatory capacity of the heart. It is said that the patient has a "compensated heart murmur": an anomaly has been detected, has been auscultated, but the patient shows a normal clinical picture and has a normal daily life.

During their annual check-up, before the vaccine, or due to any circumstance that makes us take our pet to the veterinarian, it will be detected. However, after some time without noticing that there are problems, or after many stable months, the pathology will worsen and symptoms begin to appear:

  • Intense panting, it seems that our dog is "laughing" when they undergo the same amount of exercise as they used to.
  • Exercise reluctance: they refuse to climb stairs, or lie down before finishing their daily walk.
  • Coughs, especially lying down.
  • Heaving and vomiting of white foam.
  • We can see a strange turbulence in their chest, nothing like the normal beat.

Do all chronic valve disease cases worsen?

It is clear that after years in this condition, the most common result is a worsening of their situation, but many dogs can live a perfectly normal and long life with this condition with constant care. Our dog may die from natural causes before this type of valvular insufficiency worsens, or any other unrelated illness.

The deterioration is usually progressive, not acute, so being observant and alert will help detect it. However, a small percentage of cases can suffer an acute and fatal deterioration, if the tendinous cords are broken, for example, something that happens in very few cases.

Heart Murmur in Dogs - Symptoms of chronic valvular disease

Diagnosing chronic valvular disease

Our veterinarian will suggest a series of tests, such as x-rays and an ultrasound scan of the heart (echocardiography), where the degree of valvular lesion can be known and, in the case of x-rays, heart size and possible pulmonary involvement. A complete blood analysis is also necessary.

When the heart is unable to fulfill its mission, the first area affected is the lungs, which suffer flooding known as pulmonary edema of cardiogenic origin, which qualifies as an emergency. In this case, our dog will show symptoms of severe dyspnea, literally, drowning.

Treatment of chronic valvular disease

Some veterinarians choose not to treat the condition at first sight because of the heart's ability to control the situation as long as our dog is perfectly normal and healthy.

Others, however, advocate prevention by providing the heart with relief measures. It is not a treatment in itself, as valvular degeneration cannot be reversed, but it is support so that the heart can continue to work at full capacity as long as possible. Some of these support measures are:

  • Drugs that inhibit the angiotensin converting enzyme: Explained in a simpler way, they are drugs that cause blood pressure to be reduced, which in humans we know as "blood pressure pills." The most used is bencepril once a day, for life, and can be combined later with other drugs. If the heart finds less resistance in the vessels when ejecting the blood, its operation will be better, and therefore the use of this drug is recommended from early stages.
  • Diuretics: Spironolactone, for example, is a potassium-sparing diuretic drug (others get rid of it, eventually causing problems). Although it may be diuretic, for this disease it's used for another more complicated purpose, because no drug has just one single function (just like the famous aspirin). It is said that it reduces tension and prevents fluid retention, relieving the burden on the heart.
  • Positive inotropic drugs: They increase the power of the heart's contraction. It is usually prescribed during late stages, combined with any of the above, to increase an already weakened strength of the heart muscle. Ex: pimobendan.
  • Specific diets: From a certain stage, almost never at the beginning, feeding with formulated feeds made by cardiologists may be beneficial. They base their formulation on high levels of omega 3 fatty acids, which are great protectors of the cardiac function and with a low salt content. However, an excessively early administration does not benefit the patient, so it is inadvisable to start giving it to our dog according to our own criteria. There are also oils as an independent nutritional supplement, with high omega 3 content, which could be used in both initial and final stages.
Heart Murmur in Dogs - Treatment of chronic valvular disease

Non-pharmacological treatment

In addition, we can help our dog with chronic valvular endocardiosis, with a series of healthy habits, in terms of food and care:

  • Maintain an optimum weight, according to their age and breed.
  • Short walks with regular breaks.
  • Eliminate salty treats, or fatty foods that we may be giving regularly (for example, when our dog "eats and dines" with us).
  • Give them a harness and not a collar. The trachea is moveable when the heart enlarges due to valvular insufficiency, and a harness does not compress the neck area.
  • Check-ups every 6 months or every year, as directed by our veterinarian.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Heart Murmur in Dogs, we recommend you visit our Cardiovascular diseases category.

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1 comment
Dogs name is Buddy
Can 4/6 heart murmur cause rapid weightless in my 8 year old min-pin?
He has gone from 16 lbs. To 11 in a little over two and a half months.
Just found out about heart murmur on Valentine's day?
Administrador AnimalWised

Heart problems can decrease your dog's appetite, but this is not necessarily the problem. Appetite loss is a generalized symptom with many causes, so you should go to the veterinarian for a checkup to diagnose the issue.
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Heart Murmur in Dogs