An investigation into factors influencing basal eye temperature in the domestic horse (Equus caballus) when measured using infrared thermography in field conditions

Infrared thermography (IRT) is a popular technology used for the detection of thermal changes given its non-invasive nature and lack direct contact with individual. Accordingly, maximal eye temperature (MaxET) measured IRT has been extensively applied in equine research. However, there little information available about potential limitations MaxET field studies. Thus, aims this study were to 1) quantify individual variation conditions effects individual, breed, body size (height at withers), side, sex age, 2) determine environment operator, 3) explore relationship between rectal (RT) rest. To accomplish these aims, 791 measures from 32 horses collected Sweden five different months farms over period 12 months. There was an effect on (P < .05) varied 29.4 37.6 °C. also affected by breed (maximal difference 1.1 °C 0.3 °C, respectively) but not age height withers. significant month farm differences; 2.4 2.3 respectively), outdoor indoor measurements (0.8 °C) operators (0.2 °C). no correlations RT. These results demonstrate that observed rest their home environment, endogenous (sex breed) environmental factors (farm, location year) shows We strongly suggest should be great caution studies only under where can accurately accounted for.