• horse;
  • blood;
  • sodium;
  • bicarbonate;
  • pH;
  • exercise


Twelve currently racing Standardbred horses were used to measure effects of pre-race warm-up exercise and racing on blood values for bicarbonate (HCO3), pH, base excess (BE), PCO2, sodium (Na+), calcium (Ca++), chloride (Cl) and potassium (K+). In a switchback study, 12 horses were administered NaHCO3 (454 g) dissolved in 4 litres water via nasogastric tube and 12 were given 4 litres water as a control. Horses were exercised and raced in 3 groups of 4 with 2 horses in each group on each treatment. Mean durations of the 1 mile warm-up and race were 143 and 122 s, respectively. Horses treated with NaHCOj had increased (P < 0.001) blood pH, Na+, HCO3, PCO2 and BE, while decreased (P < 0.001) K+ and Ca++ were found. Mean blood values for pH, HCO3, PCO2, BE, Ca++ and K+ in NaHCO3 treated horses, decreased (P < 0.01) after pre-race warm-up and racing. Blood Na+ increased as a result of NaHCO3 administration independent of exercise level. It is suggested that blood gas testing for the detection of illegal alkalinising agents should not be done immediately after high intensity warm-up exercise.