Equine practitioners use ultrasound machines to help diagnose a number of physical abnormalities. An ultrasound machine generates high-frequency sound waves, which echo an image back to the machine. An ultrasound is noninvasive, does not use radiation or require injecting radioactive isotopes, and provides real-time images. Horses are usually not sedated for an ultrasound examination; however, proper restraint is essential, particularly when imaging hind limbs or the reproductive tract when the images are obtained transrectally.

When viewing a sonogram, bone appears white, fluid appears black, and all other structures lie along a gray scale. Common uses of ultrasonography include reproductive tract, musculoskeletal system, respiratory system, cardiovascular system and GI tract.