Association between Cardiac Auscultation and Echocardiographic Findings in Warmblood Horses

Simple Summary In our study, we retrospectively analyzed cardiac examinations in a large number of warmblood horses conducted over a period of almost 20 years. We compared the results of the cardiac auscultation as the character and grade of a heart murmur with the results of the echocardiographic examination. We found that auscultation works very well to identify the valve affected, if following the general clinical guidelines on which kind of murmur is usually caused by specific valvular regurgitations. Auscultation is less specific in determining the grade of the regurgitation based on the loudness of the murmur. Only low-grade murmurs are usually caused by mild regurgitations, while differentiation between moderate and severe regurgitations based on the loudness of the murmur is not reliable. Moreover, we could not find that enlargement of one or more compartments of the heart generally leads to a higher-grade murmur. Heart murmurs are detected frequently when auscultating horses and certain murmurs can usually be linked to specific valvular regurgitations. Limited information exists about the accuracy of these broad rules in warmblood horses and the influence of grade of the regurgitation and dimensional changes on murmur intensity. This study aims to clarify the accuracy of cardiac auscultation in warmblood horses and the influence of the grade of regurgitation and dimensional changes on the loudness of the murmur. In this retrospective study, 822 warmblood horses presented for cardiac examination in a large equine referral center in northern Germany underwent a thorough cardiac auscultation. In total, 653 of these revealed one or more heart murmurs. Most common auscultatory findings were left-sided systolic murmurs (68%) or left-sided diastolic murmurs (15%). On 635 of these horses, an echocardiographic examination was performed, revealing regurgitations of the mitral valve as the most common valvular regurgitation (77%) followed by regurgitations of the aortic valve (23%). Thirty-one percent of horses that underwent echocardiographic examination displayed dimensional changes of one or more compartments of the heart, with the left atrium being most affected (21%), followed by the left ventricle (13%). The main goal of this study was to link certain auscultatory findings with results of the echocardiographic examinations, trying to determine whether auscultation and echocardiography agreed on the valve affected, as well as to find out if loudness of