Body temperature determination is an important component of the physical examination of an animal.1 Traditionally, veterinary practitioners have depended on equilibrium-type rectal thermometers to determine body temperature.1,2 Although usually well tolerated, rectal thermometry can be difficult in fractious animals or in animals with rectal (or perianal) disease and can be influenced by the presence of feces in the rectum.1–3 Predictive rectal thermometry measures the rate of temperature change in the first few seconds after thermometer placement to mathematically predict the final temperature; to our knowledge, this method of temperature measurement has not been evaluated in euthermic or hyperthermic dogs. Auricular thermometers were developed to provide temperature measurements less invasively.2,4,5 As with rectal thermometry, some animals resent the auricular procedure, and local pathologic changes may affect the reading obtained.2,3 A subcutaneous identification microchip with a temperature sensor has been developed for dogs and is currently marketed in Europe and Asia. To our knowledge, there are no published studies regarding accuracy or reliability of the subcutaneous microchip device for temperature determination. Although results of some studies6,7 have indicated that rectal and auricular temperatures correlate with core body temperatures in dogs, core body temperature is still considered the most accurate method of temperature assessment. Such core temperature measurements can be achieved by use of thermistors placed in the esophagus, urinary bladder, or central vascular compartment.8–12 Despite the tremendous importance of accurate temperature measurement for clinical management of dogs, there is a paucity of scientific comparison of any of the minimally invasive methods of temperature assessment with core body temperature. The purpose of the study reported here was to assess the reliability and accuracy of 3 temperature-measuring devices (a predictive rectal thermometer, an infrared auricular device designed for veterinary use, and a subcutaneous temperature-sensing microchip) for measurement of core body temperature (determined by use of a thermistor-tipped PA catheter) over a variety of temperature conditions in dogs. We hypothesized that, in dogs, rectal thermometry would provide the most reliable and accurate estimate of core body temperature among these temperature-measuring methods.
Temperature-sensing microchips, Digital Angel Corp, Saint Paul, Minn.
Welch Allyn predictive digital thermometer, Welch Allyn Inc, San Diego, Calif.
Traceable digital thermometer, Fisher Scientific, Pittsburgh, Pa.
Argon flow directed thermodilution catheter, Argon Medical, Athens, Tex.
Vet-Temp model VT-110, Advanced Monitors Corp, San Diego, Calif.
Purified LPS, Sigma, St Louis, Mo.
SAS, version 9.1, SAS Institute Inc, Cary, NC.
Skoog D, Digital Angel Corp, Saint Paul, Minn: Personal communication, 2005.
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