Cardiac and Pulmonary Auscultation

Auscultation of the heart is the most expedient and useful means by which heart disease in animals can be detected. When an experienced clinician finds the heart normal by auscultation, the likelihood of serious heart disease is very low. Definitive diagnosis can be made using a stethoscope (e.g. patent ductus arteriosus). More often a cardiovascular (CV) problem is identified by auscultation, a tentative diagnosis is developed based on the clinical situation, and a definitive diagnosis requires further studies such as Doppler echocardiography (for valvular disease, pericardial disease, cardiomyopathy, or shunts) or electrocardiography (for arrhythmias). Knowledge of normal and pathologic physiology is essential as auscultatory findings are influenced by electrical events of the heart and by the hemodynamic changes that accompany various congenital and acquired lesions. The essential abnormalities of cardiac auscultation that can be detected include abnormal intensity (loud, soft, or variable) heart sounds, abnormal rate or irregular rhythm of heart sounds (arrhythmia), extra sounds (such as gallops and clicks), split sounds, and cardiac murmurs. Other abnormalities such as friction rubs are uncommon in small animals. Respiratory sounds should be classified as well. These are summarized at the end of these notes.