<unk>  is a congenital heart defect which affects the aortic, pulmonary, mitral, and tricuspid heart valves.  Pulmonary valve stenosis and aortic valve stenosis are discussed separately.<unk>  of the mitral and tricuspid valves can cause leakage of blood or stenosis.<unk>  of the mitral and tricuspid valves - also known as the atrioventricular (AV) valves - can appear as thickened, shortened, or notched valves.  The chordae tendinae can be fused or thickened.  The papillary muscles can be enlarged or atrophied.  The cause is unknown, but genetics play a large role.  Dogs and cats with tricuspid valve<unk>  often also have an open foramen ovale, an atrial septal defect, or inflammation of the right atrial epicardium.  In dogs, tricuspid valve<unk>  can be similar to Ebstein's anomaly in humans.
Mitral valve stenosis is one of the most common congenital heart defects in cats.  In dogs, it is most commonly found in Great Danes, German Shepherd Dogs, Bull Terriers, Golden Retrievers, Newfoundlands, and Mastiffs.  Tricuspid valve<unk>  is most common in the Old English Sheepdog, German Shepherd Dog, Weimaraner, Labrador Retriever, Great Pyrenees, and sometimes the Papillon.[citation needed] It is inherited in the Labrador Retriever.
The disease and symptoms are similar to progression of acquired valve disease in older dogs.  Valve leakage leads to heart enlargement, arrhythmias, and congestive heart failure.<unk>  can be tolerated for years or progress to heart failure in the first year of life.  Diagnosis is with an echocardiogram.  The prognosis is poor with significant heart enlargement.
Heart valve dysplasia
Aortic arch anomalies
Congenital heart block
Cyanotic heart defect
Tricuspid atresia pathophysiology
Valvular heart disease
Cardiac tumors
Pulmonary valve stenosis