Stethoscopes have been used in medical fields (and non-medical fields) for over 200 years, having been invented in France in the early 19th century. Early stethoscopes consisted of a single wooden tube but by the middle of that century, a binaural (using both ears) version had been designed. Since then stethoscopes have gone through several re-designs, resulting in the modern efficient devices used in practice today.
Identifying the right stethoscope for you can initially be daunting – there is so much choice! Ultimately, a basic model which has both a bell and diaphragm region to the head piece is more than adequate for standard clinical examination. If you plan on working with particularly small animals there are stethoscopes (paediatric and neonatal) which have a smaller head piece enabling finer localisation of sounds you may hear. If you plan on moving into more advanced fields where auscultation becomes more relevant (such as Cardiology) there are more advanced stethoscopes which have improved audibility specifically for these fields. There are now also digital stethoscopes, allowing recording of heart sounds (and playback) and also assisting people with hearing difficulties.