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
Due to the dysplastic valve, the heart works less
efficiently. Other Names TVD
Causes The mode of inheritance is undefined.
Symptoms 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.
Diagnosis 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.
Treatment 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.
Prognosis 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