Use of the Portable Infrared Thermometer as a Means of Measuring Limb Surface Temperature in the Horse

SUMMARY Evaluation was made of the portable infrared thermometer to measure limb surface temperature in 3 horses—first standing in a stall and then placed in lateral recumbency under general anesthesia. To determine the effect of pigment, black and white targets were examined with the instrument under various clinical conditions. In each horse, thermal gradient measurements were consistent along the extremities. Mean limb surface temperatures were less than rectal temperature and greater than ambient temperature. Limb surface temperatures measured in lateral recumbency under general anesthesia were uniformly higher than those obtained in the standing position in the stall. The average sd of absolute temperature measurements made under general anesthesia was ± 0.1 C, whereas the average sd of those made in standing horses was ± 0.2 C. For practical use, the latter deviation of ± 0.2 C was considered more appropriate as the limit of significance for clinical measurements made with the instrument. When used indoors in the absence of direct sunlight, the influence of pigment on measurements made with the instrument was not significant. Optimal conditions for the clinical use of the portable infrared thermometer are defined and factors which affect limb surface temperature are discussed.