Background: Hypothermia during the perianaesthetic period may lead to an increased risk of morbidity in veterinary patients. However, the timeline of the decrease in body temperature during general anaesthesia has been minimally investigated.
Methods: Anaesthetic records of 1097 client-owned dogs were examined. Change in body temperature (ΔBT = baseline temperature - time point temperature) was plotted over time for all dogs. The slope of ΔBT was calculated for each 15-minute interval, and the magnitude of the largest ΔBT and the time point at which the largest ΔBT occurred were determined for each record.
Results: A rapid decline in ΔBT occurred from 0 to 15 minutes, a slower decline occurred from 15 to 60 minutes and a plateau occurred from 60 to 240 minutes. The largest ΔBT occurred at 75 (15-240) minutes from baseline, with a maximum ΔBT of -2.06°C (-0.06°C to -8.72°C).
Limitations: This is a retrospective study. As such, there were missing data points and potential confounding factors could not be controlled for.
Conclusions: Anaesthetised dogs exhibited a distinct pattern of decrease in body temperature, with the most rapid reduction occurring within the first 15 minutes. The effects of procedures and anaesthetic agents on the timeline and pattern of heat loss warrant further investigation.
Keywords: anaesthesia; dog; hypothermia; temperature.
© 2023 British Veterinary Association.