The alterations in serum concentrations of sodium, potassium, ionized calcium, urea, creatinine, glucose, creatine kinase (CK), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were studied in fifteen equines and five mules, participating in a 76km, 2-day long endurance competition, in the Pantanal of Mato Grosso State - Brazil. The blood samples were collected in the first day, before the beginning of the competition (T1); at the end of the first day, after covering 38km (T2); the second day, before the beginning of the ride (T3); and at the closure of the competition (T4). In the horses a decrease was observed in serum concentration of sodium and LDH in T4 with a return to basal values in T4. Potassium and calcium presented a decrease in concentration in T2. There was an increase of serum concentration of urea and creatinine in T2 and of glucose in T3. The serum values of CK and AST remained similar to T1. In the mules, the serum concentrations of sodium, calcium, urea, glucose and LDH presented a profile similar to the equines, while potassium, creatinine, CK and AST remained near T1 values. A difference was not observed between equines and mules serum biochemistry. It can be concluded that the studied endurance race did not impose duration and/or intensity above the physiological conditions of the participating animals.
horse; mule; endurance ride; serum biochemistry
