Reference interval for rectal temperature in healthy confined adult cats

Objectives: Despite the common use of rectal temperature for assessing health and identifying infectious diseases in cats, there is little evidence to support frequently cited feline reference intervals for rectal temperature. Body temperature measurements are most commonly performed indoors in animal shelters and veterinary clinics. In these facilities, cats are often inactive and housed in small enclosures in a climate-controlled environment. The purpose of this study was to establish a new reference interval for rectal temperature in healthy confined adult cats. Methods: Rectal temperatures were measured in 200 healthy adult indoor cats in animal shelters, veterinary clinics and private homes. The reference interval was established using the method of the Clinical and Laboratory Standards Institute. Results: The reference interval for healthy adult cat rectal temperature was determined to range from 36.7 degrees C (confidence interval [CI] = 36.6-36.8 degrees C; 98.1 degrees F [CI = 97.9-98.3 degrees F]) at the lower limit to 38.9 degrees C (CI = 38.8-39.1 degrees C; 102.1 degrees F [CI = 101.9-102.3 degrees F]) at the upper limit. The ambient temperature ranged from 20.3-30.8 degrees C (68.5-87.5 degrees F). Rectal temperature was not significantly correlated with ambient temperature. Conclusions and relevance: A range of 36.7-38.9 degrees C (98.1-102.1 degrees F) should be considered the new reference interval for healthy adult cats for rectal temperature measured indoors in climate-controlled conditions. This range is lower than commonly reported. Use of previously published ranges could lead to overdiagnosis of hypothermia or underdiagnosis of mild pyrexia.