Calcium propionate is an alkalizing agent in exercising Standardbreds

•An exercise-associated reduction was seen in plasma total CO2, HCO3- and Ca++.•Insulin and glucose were unaltered by calcium propionate (CaProp) treatment.•Strong ion difference was unaltered by CaProp treatment.•Total CO2, Ca++, HCO3- were higher in CaProp-treated horses at certain timepoints.•Calcium propionate was found to be an alkalizing agent in horses. The objective of this study was to determine if calcium propionate is an alkalizing agent in exercising Standardbreds and if it alters plasma glucose and serum insulin concentrations. This study used a randomized crossover design to test the hypotheses that calcium propionate alters total CO2 (tCO2), Ca++, pH, strong ion difference (SID), glucose, and insulin in Standardbreds completing a simulated race test (SRT) on a high-speed equine treadmill. Blood was collected from eight horses (mean age ± SD = 16 ± 2.7 years; range = 13 - 21 years) at 10 and 5 min prior to treatment or control administration, just prior to the subsequent SRT, directly after the SRT, and at 60- and 90-min post SRT. Plasma pH and plasma concentrations of tCO2, glucose, Ca++, and Na+, K+, Cl-, Lac- (for SID calculation) were measured in duplicate by blood gas analyzer and serum insulin by radioimmunoassay. Data were analyzed by two-way repeated-measures ANOVA. For plasma pH, Na+, K+, Cl-, Lac-, SID, insulin and glucose, no effects of treatment or treatment by sampling-timepoint interaction were found (p>0.05). Plasma tCO2, Ca++, pH, Na+, SID, and glucose concentrations were significantly lower, and Lac- was significantly higher, directly after the SRT compared to all other timepoints (p