Since the early 1980s, the use of ultrasound has revolutionized our understanding of mare reproductive physiology, and with it stud management. Ultrasound allows the practitioner to diagnose problems and monitor reproductive activity with considerable accuracy. Additionally, the non-invasive nature of the technique reduces the risks of harming the mare or her fetus, and allows sequential monitoring. Today, ultrasound is regularly used to monitor ovarian activity, and to diagnose and monitor pregnancy and reproductive abnormalities.

The Principles of Ultrasound

There are many different types of ultrasonic scanners available that are tailored to specific uses, but they all work the same way. A transducer emits high-frequency sound waves and receives the low-level returning echoes bounced back by tissues. The intensity and location of reflected echoes of high-frequency sound waves transmitted into the body are recorded, then translated into an image that is displayed on a monitor.

The two-dimensional image produced is black and white with intermediate shades of gray. The strength of the sound echoes depends on the density of the tissues it hits; in general, high-density tissue (such as bone) appears white, and low-density tissue (such as fluid) appears black