Infrared thermography as a non-invasive tool for quantifying emotional arousal in rats, dogs and elephants: Recent findings and methodological aspects

Infrared thermography is increasingly used in the study of emotions in humans and other animals. It measures subtle changes in superficial temperature, correlating with physiological changes such as sympathetic activation. There still is considerable potential for developing new thermographic methods. In this presentation, we share our recent work on thermography in rats, dogs and elephants. First, we present our solutions on how to design thermographic experiments for freely moving rats. We also present results on detecting two levels of emotional fever in rats, reflecting mild vs. intensive arousal, induced by exposure to ordinary vs. preferred food. We found a significant difference in forehead temperatures, compared to a neutral reference point, during the two levels of arousal (N=6, deviation from reference 2.6°C (SEM 0.2) vs. 3.0°C (SEM 0.2), F=8.4, p<0.01). Second, we present the results of an observational study in captive Asian elephants, indicating the temporal gland as a novel species-specific thermal indicator for arousal. We found a positive correlation between an elevated temporal gland temperature and arthritic knees (N=28, rs=0.73, p<0.001), suggesting arousal caused by pain. We also present pilot observations of elevated temporal gland temperatures in elephants during play. Third, we present our findings on the potential of thermography to detect lateralized nostril use in dogs, yielding information on valence. Fourth, based on our observations, we discuss methods for excluding confounding factors, such as effects of exercise, ambient temperature, air flow, dust and moisture; and address the question in which circumstances is it possible to perform accurate thermography outdoors.