PHYSIOLOGICAL RESPONSES ASSOCIATED TO THERMAL VARIATIONS DIAGNOSED BY INFRARED THERMOGRAM IN EQUINES SUBMITTED TO INTENSE PHYSICAL EFFORT

Abstract

The objective was to use infrared thermography to evaluate physiological responses in equines submitted to intense physical effort. The study was conducted in Santarém (02º 26 '35 "S and 54º 42' 30" W), in Pará, using four (4) adult equines. We performed the imaging of the head and croup with infrared thermograph before and after training. The heart rate (HR; beat.min-1) and respiratory rate (RR; mov.min-1) were monitored. The Comfort Index (CI) and the Temperature and Humidity Index (THI) were calculated. The analysis of variance and Tukey's test were performed, with a significance level of 5%. Mean, extreme and thermal amplitude data were analyzed and the correlation with the physiological variables was evaluated. We observed a THI of 79.2, indicating a challenging thermal environment for the animals. There was no significant difference (P> 0.05) in the surface temperature of the head and croup before and after training. However, we observed difference (P <0.01) in the thermal amplitude in the head region in white pattern, being higher after training and in the rump in white and yellow patterns, indicating that this variable was sensitive to detect thermal differences after training. The HR and RR were elevated after training (P <0.05). The thermal amplitude responds to the respiratory frequency of equines and can be described by a polynomial model with 70% confidence, indicating that animals with thermal amplitude higher than 1.2 ° C are already panting. We conclude that infrared thermography is recommended to detect levels of thermal stress in equines subjected to intense stress. KEYWORDS: Equines, Infrared thermography, Thermal amplitude.