LIVER ULTRASONOGRAPHY IN DOLPHINS: USE OF ULTRASONOGRAPHY TO ESTABLISH A TECHNIQUE FOR HEPATOBILIARY IMAGING AND TO EVALUATE METABOLIC DISEASE-ASSOCIATED LIVER CHANGES IN BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS).

The objective of this study was to establish a comprehensive technique for ultrasound examination of the dolphin hepatobiliary system and apply this technique to 30 dolphins to determine what, if any, sonographic changes are associated with blood-based indicators of metabolic syndrome (insulin greater than 14 μIU/ml or glucose greater than 112 mg/dl) and iron overload (transferrin saturation greater than 65%). A prospective study of individuals in a cross-sectional population with and without elevated postprandial insulin levels was performed. Twenty-nine bottlenose dolphins ( Tursiops truncatus ) in a managed collection were included in the final data analysis. An in-water ultrasound technique was developed that included detailed analysis of the liver and pancreas. Dolphins with hyperinsulinemia concentrations had larger livers compared with dolphins with nonelevated concentrations. Using stepwise, multivariate regression including blood-based indicators of metabolic syndrome in dolphins, glucose was the best predictor of and had a positive linear association with liver size (P = 0.007, R2 = 0.24). Bottlenose dolphins are susceptible to metabolic syndrome and associated complications that affect the liver, including fatty liver disease and iron overload. This study facilitated the establishment of a technique for a rapid, diagnostic, and noninvasive ultrasonographic evaluation of the dolphin liver. In addition, the study identified ultrasound-detectable hepatic changes associated primarily with elevated glucose concentration in dolphins. Future investigations will strive to detail the pathophysiological mechanisms for these changes.