Assessed Temperatures and Stress in Cats Using Tympanic and Rectal Thermometers

Previous studies using tympanic thermometers on pets have presented inconsistent conclusions. The first aim of the current study was to compare the assessed temperatures using tympanic and rectal thermometers on healthy cats in a home environment and in cats admitted to clinical care. The second aim was to compare assessed stress (Fear, Anxiety and Stress scale, FAS) in healthy cats during the tympanic and rectal measurements. The non-clinical sample included 25 cats, and the clinical sample included 36 cats. The FAS score (mean ± SD) in the non-clinical sample was significantly higher (<i>p</i> < 0.0001) during the rectal measurements (2.9 ± 0.9) than during the in-ear measurements (1.6 ± 0.9), and the temperature (mean ± SD) in both the right and left ears was higher (mean bias 0.3 ± 0.8 °C, 95% limit of agreement [-1.3, 1.8]) than the rectal temperature. The cats in the clinical sample were categorized as either hypothermic (<36.7 °C, n = 5), normothermic (36.7-38.9 °C, n = 34), or hyperthermic (>38.9 °C, n = 8) according to their rectal temperature. In the hypothermic and normothermic cats, the left ear temperature was higher (mean bias 0.4 ± 0.4 °C, [-0.4, 1.2]) than the rectal temperature. In the hyperthermic cats, the left ear temperature was slightly higher (mean bias 0.1 ± 0.3 °C, [-0.4, 0.6]) than the rectal temperature. The results indicate that the currently used tympanic thermometer can be a non-stressful tool to screen for pyrexia in cats in clinical care. However, there is a risk of normothermic cats being falsely diagnosed with pyrexia. This method is not recommended in a home environment owing to the wider limits of agreements and lower precision in the non-clinical sample, complicating the interpretation of the assessed temperatures. In the current study, there were few hypothermic (n = 5) and hyperthermic cats (n = 8), as well as cats with temperatures above 40.0 °C (n = 2); thus, further studies are needed to fully establish this method's accuracy for these patient groups.