One of the most significant advances in equine management in recent years has been the advent of ultrasonography, or ultrasound. Through this technology, which bounces repeating sound waves off tissues and structures in the horse’s body and converts them to a visual image based on the length of time it takes for the wave to return, veterinarians can examine the inner workings of soft tissues such as tendons and ligaments. Perhaps even more exciting, they can finally monitor with accuracy the mare’s reproductive cycle–and literally shed light on a mare’s unborn foal.

Like any other diagnostic tool, ultrasound has its limitations–its sound waves cannot penetrate bones, for example, translating them as white lines. Also, accurately interpreting ultrasound images, as with radiographs (X rays), requires expertise and practice. However, as a soft tissue diagnostic, ultrasound currently has no equal.

Other imaging methods do exist, but none, thus far, are as accessible as ultrasound–or as flexible. Portable ultrasound machines now are part of the regular arsenal of equipment toted by any veterinarian with an interest in reproductive work. In the approximately 15 years that ultrasound has been a part of general veterinary practice, both the level of the technology, and the expertise of the practitioners interpreting the images, have steadily improved.

An ultrasound image appears as a three-dimensional, black-and-white series of shapes, that, with practice, an operator can analyze to identify normal tissue and organs easily, and discern abnormalities. The lighter the object on the imaging screen, the more solid and dense it is, and the slower the sound waves are moving. Dark areas on the screen usually indicate fluid, through which sound waves move faster. Movement also can be detected via ultrasound–as many delighted expectant mothers have discovered upon their own visits to an ultrasound clinic