Comparison of Microchip Transponder and Noncontact Infrared Thermometry with Rectal Thermometry in Domestic Swine (Sus scrofa domestica).

During disease outbreaks, core temperature is a useful health metric in swine, due to the presence of pyrexia especially during the acute phase of infection. Despite technologic advances in other facets of swine production and health management, rectal thermometry continues to be the 'gold standard' for measuring core body temperature. However, for various reasons, collecting rectal temperatures can be difficult and unsafe depending on the housing modality. In addition, the delay between insertion of the rectal thermometer and obtaining a reading can affect measurement accuracy, especially when the pig requires physical restraint. Clearly safer, faster, and more accurate and precise temperature acquisition methods that necessitate minimal or no handling of swine are needed. We therefore compared rectal thermometers, subcutaneous microchips, and an inexpensive handheld infrared thermometer by measuring the core body temperature of 24 male castrated piglets at random intervals over a 5-wk period. The core body temperature (mean ± 1 SD) was 39.3±0.5 °C by rectal thermometry, 39.0±0.7 °C by microchip transponder, and 34.3±1.0 °C by infrared thermometry; these 3 values differed significantly. Although the readings obtain by using infrared thermometry were numerically lower than those from the other methods, it is arguably the safest method for assessing the core temperature of swine and showed strong relative correlation with rectal temperature.