Abstract

Enterohepatic circulation and prandial influence of plasma bile acids (BA) concentrations in reptiles are unknown, and there is discrepancy in BA diagnostic utility in reptiles. This study determined pre- and post-prandial BA in Krefft's river turtle (Emydura macquarii krefftii; KRT), a representative freshwater chelonian, to investigate digestive influences on plasma concentrations. Seventeen clinically healthy turtles were fasted for 10 days before pre-prandial blood was collected. Then shrimp gruel was gavage fed to all turtles and blood collected over 10 days (0.25, 0.5, 1, 2, 4, 6, 8, 10, 12, 24 h and every 24 h thereafter until 240 h). Plasma BA was determined using a colorimetric assay. A significant change in BA was demonstrated depending on time, sex, and the interaction of sex and time. Compared to other venipuncture time points, BA concentrations were consistently elevated at 24 and 48 h, and we recommend using these time points to sample BA post-prandial in this species. Overall, mean male BA were higher than female BA, and for both sexes, there were multiple elevations in BA throughout the sampling timeline. Median (interquartile range) BA and associated times for maximum values were 3.3 μmol/L (2.7 - 5.45 μmol/L) at 24 h (7.5 h - 48 h) for females and 9.4 μmol/L (4.8 - 20.73 μmol/L) at 11 h (9.5 - 24 h) for males. In conclusion, the digestive timeline of KRT appears to influence BA; however, sex and fasting status should be determined for the best interpretation of BA results in a clinical setting.