Basics of ultrasonographic examination in sheep

Abstract Diagnostic ultrasound has become an essential tool in veterinary medicine and is well established in a variety of species. Since its introduction into sheep clinical practice, it has been mainly used in pregnancy diagnosis and identification of litter size, as well as in experimental settings in reproductive medicine. Furthermore, sheep frequently serve as an experimental model in several disciplines and sub-disciplines of human medicine. However, despite of its great potential, ultrasonography does not yet play a major role in general clinical practice. The review focuses on ultrasonography in sheep and provides information in basics of ultrasound imaging. These include physical principles, instrumentation, handling and preparation of animals, imaging modes (amplitude-depth mode, brightness mode, time-motion mode, 3- and 4-dimensional ultrasound, Doppler ultrasonography), and interpretation of ultrasound images and artefacts. Examples of clinical and experimental applications are included with regard to the different imaging modes, to demonstrate how ultrasonography can be used in sheep clinical practice and research. Additionally, animal welfare as well as safety and hygiene aspects are considered.