Effects of fasting and intraluminal contrast enhancement on ultrasonographic appearance of the equine small intestine.

The equine small intestine is challenging to evaluate ultrasonographically. In humans, hydrosonography has been used to improve ultrasonographic images of the small intestine. We hypothesized that fasting horses for 24 h would enhance the ability to image the small intestine transabdominally by separating intestinal loops and reducing intraluminal gas, and that the administration of intragastric contrast agent would further improve that ability. Ten healthy horses were examined ultrasonographically under three treatment conditions: (a) regular diet, (b) after a 24-h fast, and (c) fasted plus intragastric administration of water and mineral oil. During each phase of the study, 30-s video clips were obtained from four predetermined abdominal windows, and were examined to determine diagnostic quality. Fasting improved the ability to obtain high-quality images of the small intestine significantly. The addition of contrast agent resulted in qualitative improvement in image quality, but differences did not result in statistically significant improvement.