Blood ionized calcium concentrations in horses before and after the cross-country phase of three-day event competition
Geiser, D.R.; Andrews, F.M.; Rohrbach, B.W.; White, S.L.; Maykuth, P.L.; Green, E.M.; Provenza, M.K.
American Journal of Veterinary Research 56(11): 1502-1505
1995
ISSN/ISBN: 0002-9645 PMID: 8585664 Document Number: 451572
Blood ionized calcium (Ca-2+) and pH; plasma lactate concentrations; and total protein, total calcium (Ca-T), albumin, and phosphorus concentrations in serum were determined in 40 healthy horses before (T-1), at the finish line (T-2), and 10 minutes after the finish (T-3) of the cross-country phase of a 3-day-event competition. Mean (+- SEM) Ca-2+ concentrations decreased from 6.22 +- 0.04 mg/dl at T-1 to 5.04 +- 0.07 mg/dl at T-2 (P ltoreq 0.05). This decrease was accompanied by a nonsignificant increase in Ca-T between T-1 and T-2. The mean (+- SEM) percent ionization of calcium decreased significantly (P ltoreq 0.05), from 50.9 +- 2.75% at T-1 to 40.3 +- 3.58% at T-2. Significant increases in mean albumin, total protein, phosphorus, and lactate concentrations and a significant decrease in mean pH were observed at T-2 (P ltoreq 0.05). At T-3, mean Ca-2+ and percent ionization had increased, but remained significantly less than resting values. Mean Ca-T was significantly decreased at T-3, compared with values at T-1 and T-2. Correlation of mean Ca-2+ concentration with all other measured variables at each time was evaluated; correlation coefficients between mean Ca-2+ and all other variables were low (r-2 ltoreq 0.38), indicating low biological significance.