Real‐Time Monitoring of the Core Body Temperature of Endurance Horses During Field Exercise

Abstract

IntroductionContinuous monitoring of core body temperature may provide useful information about the thermal response to metabolic heat load and environmental challenges. The aim of this study was to evaluate a telemetric gastrointestinal (GI) pill (Equivital®) measuring gastrointestinal temperature (GT) during endurance exercise. It was hypothesised that a temperature and metabolic heat profile could be established.MethodsThe GI pill was administered to 6 horses by nasogastric tube (n = 3) or modified‐drench gun (n = 3), the day before competition. During competition, GT, skin temperature and heart rate (HR) were recorded (by Equivital® belt). Other data collected included body weight and rectal temperature (RT), GPS/HR monitor information, and environmental conditions using a data logger. Metabolic heat production was calculated [1] and GT correlations were explored using simple correlation estimates (P<0.05).ResultsData were collected from 6 horses during 80 km (n = 4 horses) and 100 km (n = 2) competition days with mean data loss of 7.4% (±2.4%). GT profiles showed increasing temperature with cumulative metabolic heat production, and time to reach maximum GT was 2.14–6.29 h (maximum GT range: 38.4–39.5°C). During exercise (7 h 6 min ± 1 h 3 min duration), mean and maximum speeds ranged from 10.1–14.5 km/h and 23.5–30.8 km/h, respectively. No correlation was found between GT and HR, skin, or environment temperature. Maximum GT increased with bodyweight (r = 0.775, P = 0.08). GT was systematically higher than RT (mean difference +0.46°C).ConclusionsGT was recorded successfully during competition with minimal data loss. The GI pill has great potential as a method to further investigate thermoregulation in horses under field conditions.Ethical Animal ResearchAll studies were performed under the Adelaide Animal Ethics Committee, University of Adelaide. Explicit owner informed consent for participation in this study is not stated. Sources of funding: The equipment for the project was funded by the Faculty of Science ‘Grant for minor equipment’, University of Adelaide, Australia. Competing interests: none.