Tricuspid Valve Dysplasia

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.

How is tricuspid dysplasia inherited?

The mode of inheritance is undefined.

What breeds are affected by tricuspid dysplasia?

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.

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a general consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What does tricuspid dysplasia mean to your dog & you?

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.

How is tricuspid dysplasia diagnosed?

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.

FOR THE VETERINARIAN

MURMUR: soft to loud holosystolic murmur over the tricuspid valve and right apex area (fourth intercostal space at costochondral junction).

ELECTOCARDIOGRAM: right atrial and ventricular enlargement. Atrial arrhythmias, especially atrial fibrillation, are common. Ventricular conduction disturbances may be seen as well.

RADIOGRAPHS: right atrial and ventricular enlargement, may see under-perfusion of lungs.

ECHOCARDIOGRAPHY: may see abnormal location, shape, motion or attachment of the valve apparatus. Doppler assessment will show an abnormal flow - regurgitant jet or valvular stenosis or both.

OTHER: With right-sided heart failure, you may see jugular distension and jugular pulses, cool limbs, hepatomegaly and ascites.

How is tricuspid dysplasia treated?

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.

Breeding advice

Affected individuals and their parents should not be used for breeding. Siblings should only be used after careful screening.

One obstacle to controlling tricuspid valve disease is that clinical signs associated with the disorder are generally not evident until after a dog has reached breeding age. However a heart murmur can often be detected long before the onset of clinical signs. Breeders are encouraged to select mature rather than young dogs for breeding, that have been certified free of murmurs.

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FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Resources: Patterson, D.F. 1996. The genetics of canine congenital heart disease. ACVIM-Proceedings of the 14th Annual Veterinary Medical Forum: 225-226. This reference has good information for breeders and veterinarians regarding screening and genetic counseling for congenital heart defects.

Copyright © 1998 Canine Inherited Disorders Database.
All rights reserved. Revised: August 06, 2003.
Reprinted with permission

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