Plasmatic levels of carnosine and l-histidine in horses under treadmill standardised exercise

The aim of this study was to detect the variations of Carnosine (Carn) and l-Histidine (l-Hist) concentrations in horse blood plasma as a potential indicator of muscle status during 2 treadmill standardised exercise test (SET) executed at 48 hours one to the other. The concentrations of both molecules increased during all SET; l-Hist concentrations were alwayshigher than Carn ones. Significant increases were found between the values of Carn and of l-Hist during the second SET and in the first versus the second SET (p<0.05) and Carn during thefirst SET (p<0.005). A positive correlation was found in each horse between Carn and l-Hist values (p<0.05). The higher basal values observed during the second SET could be due to the absence in plasma of carnosinase and/or to subclinical muscle damages in untrained horse. Plasma concentrations of these molecules can be useful as clinical indicators of muscle damageand could be utilized to plan SET.