Imaging of the equine abdomen using point of care ultrasound (POCUS): Effects of sedation on intestinal motility in horses

Background: Point of care ultrasonographic (POCUS) assessment of the equine abdomen is now readily available to the equine practitioner using hand-held ultrasound transducers. Commonly used medications may alter the sonographic appearance or function of the small intestine, caecum or colon. Aim: To demonstrate qualitative and quantitative effects of xylazine sedation on intestinal motility of healthy horses using hand-held, wi-fi ultrasound transducers and validate POCUS methodology by determination of intra- and interobserver agreement. Methodology: Double-blind cross-over study of eight healthy horses using hand-held, wi-fi ultrasound transducers to determine the effects of sedation on intestinal motility in comparison with administration of a placebo (saline). Motility was independently assessed by three observers using deidentified videos obtained using hand-held, wi-fi ultrasound transducers. Agreement was assessed by determination of intraclass correlation coefficient (number of duodenal contractions) and weighted kappa statistic for motility grades. Findings: Sedation was associated with fewer duodenal contractions (median 0.5, range 0 to 2) after sedation, compared with administration of saline (median 4, range 3 to 5, p < 0.001). Large colon and composite motility grades were also reduced (median 4.5, range 2 to 6 after sedation; median 10, range 7 to 12, after saline, p = 0.005), and qualitative changes were evident in the sonographic appearance of jejunal loops in six of eight horses. Interobserver agreement was moderate to good, and intraobserver agreement was good to excellent. Conclusion: POCUS proved to be an effective tool to recognise qualitative and quantitative changes associated with sedation.