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Chronic Valvular Heart Disease

Randy Walker DVM

About Chronic Valvular Heart Disease...

Chronic Valvular Heart Disease (also called a "heart murmur", a "leaky valve", or "congestive heart disease'') is a condition of dogs (and some cats) in which the valves of the heart become shrunken and "leaky" thereby interfering with proper function of the heart.

Briefly, Describe The Normal Heart And How The Heart Is Different In The Patient With Chronic Valvular Disease?

In the normal heart, unoxygenated blood carrying carton dioxide (a metabolic waste product of the metabolism of cells) returns from the body into the right side of the heart. Then the valve between the veins and the right side of the heart closes tightly, making sure that no blood can back up into the veins. When the heart beats again the unoxygenated blood is moved from the right side of the heart to the lungs where it releases the carbon dioxide (expelled when the dog exhales) and receives oxygen (from the air inhaled). Then, when the heart beats again, the blood is moved into the left side of the heart and a valve shuts off tightly to prevent back flow of blood into the lungs. When the heart beats again the blood with its oxygen is pumped back out to the body tissues. In the patient with chronic valvular disease one or more of these valves becomes shrunken, distorted, and "leaky". This allows some of the blood to backup through this leaky valve instead of all the blood moving in the direction it's supposed to, which eventually leads to serious health problems.

What Are The Clinical Symptoms Of Congestive Heart Disease Secondary To Chronic Valvular Disease?

This depends to a large extent on which heart valves are affected. For example, if the valve between the veins and the right side of the heart is "leaky", blood will back up through this leaky valve and increase the blood pressure in the veins leading to edema, ascites (retention of water in the abdominal cavity), weight loss, unthriftiness, and enlarged abdominal organs. If the valve between the lungs and the left side of the heart is "leaky", blood will back up into the vessels of the lungs leading to pulmonary edema, causing an increase in blood pressure, leading to exercise intolerance (tires easily), weight loss, unthriftiness, coughing, difficult breathing, and poorly oxygenated blood (called cyanosis). A stethoscope can often be used to detect the characteristic murmur of the leaky valve and to help localize which valves are most affected. Sometimes both sides of the heart have leaky valves and when this happens you can see some of each set of clinical symptoms. Both right and left sided congestive heart disease are very serious and can lead to premature death in many cases.

Which Patients Are Most Likely To Get Chronic Valvular Heart Disease?

Most cases of chronic valvular heart disease are acquired and most of them arise secondary to chronic infections. The most common infection that can lead to a heart murmur and chronic valvular disease is chronic tooth and gum infection. Chronic skin, ear, or eye infections can sometimes result in chronic valvular heart disease. Any infection that enters the bloodstream can potentially lodge on the valves of the heart (a condition called valvular endocardiosis) and lead to valvular disease. "Leaky valves" can also be due to birth defects, heartworm disease, and also the age of the valves. The tendency to acquire valvular disease can also be inherited and runs along family lines. Toy poodles, Bichons, and Chihuahuas among others are especially prone to inheriting valve defects.

How Is Chronic Valvular Heart Disease Diagnosed?

Diagnosis is based on history, physical exam, and test results. Usually a heart murmur is detected on physical. exam and this indicates the need for further evaluation. To evaluate the heart function we usually take radiographs and perform an ultrasound exam of the heart. Ultrasound (called echocardiography) is the best way to evaluate the heart function, contractility, valve function, and cardiac output among other things.

How Is Valvular Disease Treated?

Depending on the ultrasound results, the patient is given medications to (1) reduce the volume of blood to be pumped; (2) lower the blood pressure; and (3) strengthen the heart. Similar to people with heart problems, the dog is often placed on a potassium enriched, low-salt diet. Unlike human beings, we do not have valve replacement operations in animals but, with proper medications and diet, we can often extend the life expectancy of these patients significantly.

How Can I Learn More About Chronic Valvular Heart Disease?

Just call your regular veterinarian and they'll be glad to tell you more!

- Randy Walker DVM
Sun Lakes Animal Clinic
May 14,2004

"Until one has loved an animal, a part of one's soul remains unawakened."
- Anatole France, 1921 Nobel Prize Speech -

Titlebar Image: The Gentle Doctor, 1937-38 by Christian Peterson (U84.179) - Iowa State University