Comparison of rectal and tympanic membrane temperature in healthy exercising dogs

The ability to monitor body temperature in athletes at risk of hyperthermia is essential in all species. Currently, the only commonly accepted temperature monitoring site in dogs is the rectum. This is impractical in field situations as it takes time, requires additional handlers to restrain the dog and is not tolerated by all animals. Tympanic membrane temperature (TMT) monitoring may provide a rapid measure of body temperature to facilitate identification of heat stress and heat stroke in canine athletes. In human studies, TMT diverges from rectal temperature (RT) as body temperature increases during exercise induced hyperthermia so is not recommended for monitoring human athletes. If the same divergence occurs in dogs, TMT may not be suitable for use when monitoring the temperature of canine athletes. The aim of the study was to determine if TMT diverged from RT following exercise in healthy dogs. 24 healthy dogs were recruited to the study. Body temperature was measured using a veterinary auricular infrared thermometer (VetTemp) to record tympanic membrane temperature and an electric predictive rectal thermometer. Temperatures were recorded pre and post exercise in a non-clinical setting, familiar to the dogs. The mixed model approach showed that exercise had no effect on the difference between RT and TMT (F(1,201) =0.026, P=0.872). The overall mean difference of RT minus TMT was 0.39°C (n = 116). 68.4% of readings fell within the accepted 0.5°C difference in temperature recording method. In line with previously reported TMT to RT comparison studies in dogs, this study found that TMT measured consistently lower than RT. Using a correction factor of 0.4°C minimised the difference. The hypothesis that dogs would show greater differences between TMT and RT following exercise was not supported, suggesting that TMT could be used to monitor body temperature in exercising dogs where RT is not possible