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Issue Description
The atrioventricular (AV) valves in the heart ensure that the blood flows from the atria to the ventricles when the heart beats. Malformation (dysplasia) of the right atrioventricular (tricuspid) valve causes backflow of blood into the right atrium, or tricuspid regurgitation. There may also be narrowing (stenosis) of the valve.

Due to the dysplastic valve, the heart works less efficiently.

Other Names
Tricuspid Valve Dysplasia

The mode of inheritance is undefined.

Often animals will live for several years without developing heart disease. More severely affected animals with a greater degree of regurgitation and/or stenosis across the defective valve, will develop right-sided heart failure. Signs may include cool limbs and a distended abdomen due to an enlarged liver or build-up of fluid. Your dog may also have a reduced tolerance for exercise and may experience fainting or collapse due to an abnormal heart rhythm.

Your veterinarian may detect a heart murmur long before your dog is showing any signs associated with a tricuspid defect. Further investigation by radiographs and electrocardiogram may reveal some of the changes that occur in the heart over time, as it works harder to compensate for the insufficiency of the tricuspid valve. Some of the changes that may be seen include enlargement of the right side of the heart and abnormal heart rhythms.

It may be many years before heart disease develops. If and when it does, your veterinarian can recommend several medical therapies to ease life for your dog. Depending on the stage of heart disease, these may include a special sodium-restricted diet, exercise restriction, diuretics to reduce fluid build-up, and medication to support the failing heart. The defective valve itself can not be replaced surgically at this time.

Survival of dogs with TVD is dependent on the extent to which the normal function of the valve is compromised. The more severe the condition, the greater the amount of blood regurgitation and the resulting enlargement of the right side. Surprisingly, however, many dogs with severe TVD exhibit no symptoms until they are in congestive heart failure. Once symptoms of congestive heart failure occur, the affected dog usually succumbs rapidly to the condition. Treatment is limited to controlling symptoms secondary to the failing heart. Exercise should be restricted to avoid overtaxing the already burdened heart. Diuretics can be administered to control fluid retention and digoxin can be administered to regulate atrial arrythmia, if present. Despite clinical intervention, the average life expectancy for dogs with TVD is 1-3 years.

Breeds Most Affected
This is mostly seen in larger breeds, especially the Borzoi, Boxer, German Shepherd, Great Dane, Great Pyrenees, Irish Setter, Labrador Retriever, Newfoundland, Old English Sheepdog, and Weimaraner. Tricuspid dysplasia is more common in males than females.

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