Mitral Valve Insufficiency in Dogs
The most important factor with this condition is that you cannot compare a dogs heart to a human heart

Mitral valve insufficiency in dogs can occur at any age, but it is much more common in older dogs. However, this condition also occurs more commonly in smaller breeds.

It is perhaps better known by a much more familiar name; heart failure.

Heart failure in dogs usually means one simple thing; the muscles in their heart have simply given out.

When this does occur, it is usually the result by one chamber or side of your dog’s heart that is forced to do more work that it was designed to do.

In fully understanding what mitral valve insufficiency in dogs is, it is very helpful to understand how your dog’s heart works.


In fully understanding mitral valve insufficiency in dogs, it is very helpful to understand exactly what your dog’s heart does.

Their heart is very similar to a pump and how it works, as it accepts blood on one side of then forces it through the lungs.

Once that is completed, the other half pumps the blood through their entire body.

Your dog’s heart, however, does not change their blood in any way at all.

It simply is the mechanism that moves the blood in the correct directions.

The heart in a dog has no glandular tissues at all, and contrary to some misconception, it does not secret or extract anything from the blood.

To put it very simply, it is extremely complex, but at the same time, very easy to understand. In fact, it is the easiest of all of your dog’s organs to understand if you view it as simply a pump.

When the blood from your dog’s body enters into the right upper chamber, it is entering what is referred to as the right atrium.

From here, your dog’s blood now has two distinctive characteristics; it is low in oxygen but it has very high levels of carbon dioxide.

From the right atrium, your dog’s heart than moves the blood into what is referred to as the right atrioventricular valve.

The right atrioventricular valve is a much larger chamber, and from here their heart physically forces the blood into the lung field through what is called the pulmonary artery.

This artery in your dog is the only artery in their body that carries non-oxygenated blood.

The carbon dioxide that is present in your dog is actually a by-product of their body metabolism, and as a result of this process, it attaches to their bloods red blood cells.

Once the carbon dioxide enters into your dog’s lungs, it is replaced with oxygen.

Beagle dogsMitral valve insufficiency in dogs has one chilling symptom--coughing

Once the blood has been regenerated with oxygen, it than moves through the pulmonary vein where it returns to the heart and enters their left atrium.

This chamber than pumps your dog’s blood through their mitral valve into the left ventricle, which is considered not only the largest chamber of their heart, but also the most muscular.

The other chambers in your dog’s heart will only move their blood short distances at a time, while the left ventricle forces the blood throughout their entire body through the aorta.


There is still one other issue that is very helpful in understanding mitral valve insufficiency in dogs; you cannot compare a human heart to your dog’s heart.

In humans, heart disease and failure can involve several processes.

It can involve the arteries that supply the blood to the heart hardening, losing their elasticity, or the ability to properly respond to blood pressure differences.

These differences usually involve the distribution of blood to the cardiac muscle.

However, there are other instances where these issues may involve an inadequate diet, plaque build up in the arteries, or genetics.

Although some of these issues may develop in your dog, they are considered to be extremely rare. However, what is not rare is the development of mitral valve insufficiency in dogs.

When this occurs in your dog it is a much simpler process; your dog’s heart muscles have worn out.

The reason for this is also usually very simple; one side or one chamber is burdened with the task of doing more than it can handle.

However, there may be some instances where your dog’s heart requires excessive force to pump the blood, but the result is the same; the muscles simply cannot handle this and they wear out.

There is one other major difference between human hearts and your dog’s heart; heart attacks.

As anyone is quite familiar with, human heart attacks usually occur very suddenly and in most cases, unexpectedly.

However, in dogs it is exactly the opposite.

A heart attack in dogs is a very slow and absolutely excruciating process that can last months, or even years in some cases.

Mitral valve insufficiency in dogs usually occurs as they age, but it can affect all breeds at any age.

However, there are some breeds that are at a higher risk of this heart condition. These breeds include any of the smaller breeds, but the reason is not fully understood.

However, what is fully understood is what happens with mitral valve insufficiency in dogs .

As your dog ages, their mitral valve begins to weaken. Once it reaches a certain point, it fails to operate properly.

A heart valve in your dog is designed to prevent any back flow that may occur.

Your dog’s blood can very easily be pumped through the valve, but if the more forward chamber is filled up, the valve will close to prevent the blood from flowing backwards into their atrium.

When these valves are operating properly, they greatly enhance the hearts overall efficiency, as their blood only has to be pumped once.

However, if back spill of blood does occur, it now requires extra effort to move it forward again.

When mitral valve insufficiency in dogs does develop, the values do two things over time; they age and they shrink.

When this becomes a deficiency, they will not close off the area on the left side of the heart between your dog’s two chambers.

From this point on, every heartbeat in your dog forces blood backwards into the left atrium.

If everything was normal in your dog, the pressure is higher in their left ventricle, as its major job is to force blood into their entire body.

But when it flows backward, it elevates the blood pressure in the affected chamber and in some cases, even back into their lung field.

All of this requires one side to work much harder than it is designed to do, and mitral valve insufficiency in dogs, or heart failure, is the result.


Because of this entire process, the symptoms with mitral valve insufficiency in dogs are very easy to identify.

If your dog develops what is referred to as hypertension or high blood pressure, your dog will develop fluid in their lungs.

What is happening is that fluid is leaving your dog’s blood vessels and is entering into their tissues.

This is also referred to as pulmonary edema and the symptoms are very direct and frightening; coughing.

Coughing is the worst sound you will ever hear in your dog, and this is the main reason why it is so dangerous. This coughing will usually occur after exercise or any kind of excitement.

It may also occur when your dog first wakes up. As the condition becomes worse, your dog may also become very weak and may start to faint very easily.


Mitral valve insufficiency in dogs can never be totally prevented; however, it can be slowed and controlled to some extent.

Maintaining your dog’s weight has several advantages, but none bigger then with this condition.

Extra weight will only exasperate the situation. Your dog’s heart valves can also be subject to infections, and the major cause of these infections is by severe dental problems.

If you do have a smaller breed or an older dog, controlling their weight and their dental issues may very well help to extend their life.

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