Applicability of thermography as a potential non-invasive technique to assess the body-thermal status of heat-stressed and water-deprived goats (Capra hircus).

To evaluate the use of infrared thermography to assess the thermal status of heat-stressed and water-deprived Capra hircus, full-body surface temperature (T) and six other body-thermal variables [core, rectal (T), and skin (T) temperatures, respiratory and heart rates, and total body-thermal gradient (core-to-ambient, BTG)] were measured after three days of euhydration (EU), dehydration (DE), and rehydration (RE). Results revealed that the combined effect of heat stress and water deprivation had affected all tested variables including the T, and once these animals gained access to water in the RE stage variables returned to their EU levels. Moreover, there were positive correlations between T and all variables with the exception of BTG. From these six variables, only three variables (i.e. the T, T, and BTG) during the DE stage and two variables (i.e. the T and BTG) throughout the experimental stages showed higher constancy (R ≥ 0 75, P < 0 001; agreement intervals ±1 96 95 % CI) with T. However, BTG appeared more closely correlated with T, representing the body-thermal status more realistically than other variables. In effect, the mean and thresholds of the BTG were predicted using the recorded T and were within 0.02 °C of original estimates. Collectively, these findings show that infrared thermography is appropriate for assessing body-thermal status, and thus the welfare, of these animals under the three conditions studied, and conclude that full-body T can be a surrogate proxy for BTG in these animals. Further experiments are needed to adequately examine the reproducibility of these results under biometeorologically-simulated environments and natural habitats.