Echocardiographic evaluation of cardiac structure and function in broiler and Leghorn chickens

This study was conducted to validate echocardiography in chickens, and to compare cardiac structure and function between broiler and Leghorn chickens. Diameters of the right and left ventricles, and thicknesses of the left ventricular free wall and the interventricular septum were measured echocardiographically in 5- and 7-wk-old chickens from both lines. Images were obtained from minimally restrained, standing birds using a 7.5 MHz probe placed in a parasternal position. End-systolic and end-diastolic echocardiographic measurements were compared with post-mortem measurements of the same variables. Comparisons resulted in correlation coefficients greater than 0.70 between in vivo (echocardiographic) and post-mortem measurements of the same variables, with post-mortem measurements more closely resembling end-diastolic echocardiographic measurements. After being normalized to body weight, post-mortem myocardial thicknesses, aortic and left ventricular diameters, heart weight at 5 wk of age, and left ventricular weight at 7 wk of age were smaller in broiler than in Leghorn chickens. Echocardiographic parameters, including ventricular wall thicknesses, ventricular diameters, and left ventricular fractional shortening, were also smaller in the broiler chicken. Right ventricular fractional shortening did not differ between the chicken lines. These results indicate that echocardiography is a useful noninvasive technique for in vivo evaluation of cardiac structure and function in the chicken, and that broiler chickens have a relatively smaller structural and functional heart than Leghorn chickens.