Ultrasonographic examination of the heart in sheep

In sheep, echocardiography (ultrasonographic examination of the heart) includes two-dimensional examination, with which right or left parasternal images are taken, employed to image the various anatomical structures of the heart, M-mode examination, employed to image one-dimensional views of the heart visualised over time, and conventional Doppler examination, employed to record normal blood flow velocities through the cardiac valves and great vessels and to detect abnormalities of blood flow through these structures and through the interatrial or interventricular septum. Several studies have proposed reference values for the various echocardiographic parametres in healthy sheep; however, differences occur between authors, which may arise from lack of consistency regarding animal age, sex, weight, status of consciousness, breed, as well as technique employed. There is limited scope in clinical use of the methodology, due to the small incidence risk and clinical significance of cardiac disorders in sheep; there are a few case reports of specific heart diseases in sheep investigated by means of echocardiography; these include congenital heart defects, calcinosis, myocardial disease (myocarditis and cardiomyopathy), endocarditis, pericarditis and cardiac tumour. The main application of echocardiography in sheep refers to using the animals as models in human cardiovascular research, where it can be applied in models for development of functional indices, for evaluating systolic and diastolic left ventricular performance, for studying valvular disorders and for investigating effects of intracoronary microembolisation; results of echocardiography applied in sheep have indicated that the model is suitable for extrapolating results in humans.