Physiologic responses of acclimatized or non-acclimatized mature reininghorses to heat stress: I. Heart rate, respiration rate, lactate, rectaltemperature, cortisol and packed cell volume

摘要

An experiment was conducted utilizing twenty mature Quarter Horses to establish physiologic responses to reining training under conditions conducive to heat stress. Ten of the horses were acclimatized to ambient conditions [30 degreesC, 80% relative humidity (RH)] for 28 days while the other ten were acclimatized simultaneously to 20 degreesC and 50% RH in an air-conditioned facility. On day 28 standard exercise testing (SET)(1) was conducted in ambient conditions (30 degreesC, 80% RH) for both groups of horses and was repeated on day 30 and day 32 of the protocol. Heart rate and plasma lactate concentration revealed that galloping circles, spinning and stopping were more taxing maneuvers for the unacclimatized horses on day 28. However, these differences were less significant on day 30 and were not observed on day 32 indicating that it took the horses approximately five days to become acclimatized to ambient conditions.