Comparison of post-exercise cooling methods in horses

Comparison of post-exercise cooling methods in horses

Exertional heat illness (EHI) following strenuous exercise un- der hot and humid conditions can be detrimental in horses. Direct cooling after intense exercise is necessary to prevent EHI. There- fore, this study aimed to evaluate the efficacy of 3 cooling meth- ods in horses post treadmill exercise. Five mature geldings were treadmill exercised on 3 consecutive weeks to determine the effect of 3 post-exercise cool-down methods (5 ×3 Latin square design). These methods were (i) no water application (W no ), (ii) cold water application only (W only ; pouring 30 L of cold water (6 °C) every min for 6 min) and (iii) cold water application with scraping (W scraping ; cold water (6 °C) application followed by scraping after each wa- ter application). After 6 min active cool-down phase, the horses were walked in-hand (walking phase) for 4 min and stood (stand- ing phase) for 35 min. Central venous temperature (T CV ) and rec- tal temperature (T R ) were selected and measured simultaneously. The collected temperatures were paired and statistically analyzed by Wilcoxon signed rank test to assess the efficiency of cooling be- tween methods. The room temperature and humidity in the tread- mill room for the treadmill exercise was (mean ±SD) 27.2 ±1.3 °C and 49.9 ±7.2% and in the corridor for cooling down was 30.0 ±2.2 °C and 49.0 ±8.6%. Greater T CV and T R reductions were ob- served when cold water (W only & W scraping ) was applied compared with no water application (W no ) (T CV : −0.91 °C for W only -W no , P < 0.001, −0.84 °C for W scraping -W no , P < 0.001; T R : −0.31 °C for W only - W no , P < 0.001, −0.29 °C for W scraping -W no , P < 0.001), and overall the water application had more cooling down effect on T CV than T R ( −0.57 °C, P < 0.001). Between the 2 applied cold water meth- ods, significantly lower body temperatures (T CV −0.11 °C, P = 0.01; T R −0.03 °C, P = 0.01) were observed with W only than W scraping . This study demonstrates that constant contact with water is more im- portant for heat conduction and more effective than producing and using sweat evaporation to remove heat. Application of wa- ter without scraping may help decrease the core body temperature in horses more effectively in the early stage of EHI.

Keywords: Heat Stress, Exercise, Cool-Down