What is the most common instrument used to listen to heart sounds in animals?

The most common instrument used to listen to heart sounds in animals is the stethoscope. This tool allows veterinary professionals to assess heart function by amplifying the sounds produced by the heart, such as beats and murmurs, making it easier to evaluate the animal's cardiovascular health. The stethoscope typically consists of a chest piece, which contains a diaphragm and/or bell to capture different sound frequencies, and it is designed for non-invasive examination of internal sounds.

While the other instruments serve important functions in veterinary practice, they do not serve the specific purpose of listening to heart sounds. A sphygmomanometer is used to measure blood pressure, providing data on the circulatory system but not the heart sounds directly. A thermometer is essential for measuring body temperature, which is critical in diagnosing illness but unrelated to heart sound evaluation. An otoscope is utilized to examine the ears, primarily assessing the ear canal and eardrum, rather than the heart. Therefore, the stethoscope is uniquely suited for auscultation of heart sounds, making it the correct choice in this context.