Comparison of Rectal and Infrared Thermometry Temperatures in Anesthetized Swine (Sus scrofa)

Infrared thermometry (IRTM) is a noncontact method to measure temperature. The purpose of this study was to compare rectal temperature and IRTM in healthy anesthetized swine, with the hypothesis that IRTM would be an accurate, noninvasive alternative for rectal temperature measurement. Two groups of female Yorkshire-cross swine (n = 14 and n = 12) were sedated with Tiletamine-zolazepam (0.5 mg/kg) for blood collection during a routine physical examination. While sedated, rectal temperatures were measured using a SureTemp Plus 690 (Welch Allyn) and IRTM measurements were taken using a FLIR E5 thermal imaging camera. The 2 anatomic sites used for thermography measurements were the area surrounding the eye and the neck at the base of the ear. The distance from the imaging camera and the animal during IRTM measurements was 24 to 32 inches, a distance that would allow camera access in a standard swine enclosure. The infrared imaging camera's surface temperature measurement exhibited a proportional bias when compared with the rectal temperature. All rectal temperature measurements were between 98.7 °F to 101.3 °F, with a mean temperature of 100.4 °F. IRTM tended to underestimate rectal temperatures at lower values, and overestimate rectal temperatures at higher values by approximately (+) or (-) 0.8 °F of rectal temperature. Infrared thermometry can provide a quick noninvasive assessment of the body surface temperature, without the need for animal handling or restraint, but should not be considered an accurate replacement for rectal temperature measurement.