INTRODUTIONPhysical exercise is responsible for alterations in various blood parameters (KIENZLE et al., 2006). Biochemical (TOLEDO et al., 2001), hydroelectrolytic (DI FILIPPO et al., 2009;, hormonal and metabolic (NOLETO et al., 2016) changes have been described in horses submitted to exercise of different intensities and durations. These changes occur as the organism attempts to adapt and supply the increased metabolic demand triggered by physical effort (PICCIONE et al., 2007) and are under most circumstances considered beneficial to the animal. However, physical exertion, when overly exhaustive or without proper training, can induce severe organic alterations, especially when the different tissues, organs or systems are not sufficiently adapted to support the different types of overload required of them without causing large changes in homeostasis (OGONOVSZKY et al., 2005