Lithium concentration in biological samples and gender difference in athletic horses

Lithium (Li⁺) represent a substance particularly used for human psychiatric disorders but its therapeutic effect is not well documented for equine specie. For its neurotrophic effect, it may be used as a possible doping substance in horses sports competitions. The purpose of the present study was to determine the different bioaccumulation of lithium concentrations in different biological substrates (blood, serum, mane, and tail), in 30 horses (15 geldings and 15 mares) and hematological parameters as blood biomarkers for lithium bioaccumulation. (RBC, WBC, HGB, HCT, MCV, MCH, MCHC). The lithium concentration in substrates were analyzed by one-way ANOVA. An unpaired t-test was performed between geldings and mares in all substrates. Furthermore, a single regression analysis (Pearson) has been carried out between the lithium concentrations of all biological substrates with each other and between the substrates with the hematological parameters. Our results showed a higher value of lithium concentration in blood and mane in total, and a higher value in mane and tail for mares than geldings. Correlation analysis showed only a significant correlation among blood, serum, and tail. A significates statistical correlation between blood and all hematological parameters except for WBC and MCH was observed. A significant correlation was shown for serum and RBC, HGB and HCT, and between tail and HGB, HCT and MCHC. No significant correlation was observed for mane and hematological parameters. These data could be useful for the evaluation of biodistribution of lithium in an athletic horse in relation to different gender for future use in doping control.