Agreement between body surface and rectal temperature in cats

Measuring body temperature in cats is an essential part of every clinical examination. Typically, rectal temperature measurement is conducted, but the procedure is poorly tolerated, and it often triggers stress-related changes in physiological parameters like pulse rate and blood pressure. Therefore, non-contact infrared thermometers have been studied on a few body surface measurement sites. However, existing studies included only commercial thermometers, which do not guarantee the correct temperature readings. In this study, we applied a custom-made and calibrated infrared thermometer for measuring feline body surface temperature on easily-accessible measurement sites of the eye, gum, and inguinal region. Results showed that body surface temperature was correlated poorly with rectal temperature, achieving the Spearman correlation coefficient of up to 0.25. Furthermore, the differences between body surface and rectal temperate were high (± 4°C). However, the infrared thermometer-based measurements provoked significantly lower stress response, achieving an average stress score of 2.8 (5 being maximum). On the other hand, rectal measurements resulted in a mean stress score of 3.7. Although the non-contact body surface temperature measurements with an infrared thermometer were tolerated significantly better, the poor agreement with rectal temperature prevents the approach to be endorsed for clinical body temperature measurements in cats.