Ebstein's anomaly is a congenital heart defect where the opening of the tricuspid valve on the right side of the heart, between the right atrium and the right ventricle is displaced toward the apex of the right ventricle of the heart. It is accompanied with tricuspid insufficiency or stenosis. An abnormal accessory pathway may lead to rapid heart rhythm. A murmur can be heard with a stethoscope though it can be difficult to hear if there is stenosis. Dogs with mild tricuspid insufficiency or stenosis will be asymptomatic; however those with moderate insufficiency or stenosis may show exercise intolerance. Severe cases may suffer from congestive heart failure (CHF) with fluid in the chest or abdomen. There may be some fatigue or dizziness associated with this condition, due to the increased pressure on the heart to function.