Influence of fentanyl, medetomidine-fentanyl or acepromazine-fentanyl premedication on oesophageal and rectal temperature in dogs under anaesthesia

Abstract

ObjectiveTo compare changes in oesophageal (T-Oeso) and rectal (T-Rec) temperature in dogs during general anaesthesia and premedicated with fentanyl, medetomidine–fentanyl or acepromazine–fentanyl. Study designProspective, randomized, blind clinical study. AnimalsA total of 120 healthy dogs, aged 2–10 years and weighing 5–20 kg. MethodsDogs were randomly allocated to one of three groups. Animals of F group were premedicated with fentanyl (0.01 mg kg–1), MF group with medetomidine (0.005 mg kg–1) and fentanyl (0.01 mg kg–1) and AF group with acepromazine (0.01 mg kg–1) and fentanyl (0.01 mg kg–1). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen–air mixture. Fentanyl was administered continuously (0.01 mg kg–1 hour–1). The T-Oeso, T-Rec and ambient temperatures were recorded after induction (T0) and subsequently at 10 minute intervals for 60 minutes (T10–T60). Data were analysed using anova or their non-parametric equivalents (p < 0.05). ResultsMedian T-Oeso was significantly higher in MF group between T0–T20 compared with other groups. Median T-Oeso significantly decreased in F group from 38.0 °C (T0) to 37.4 °C (T30), 37.1 °C (T40), 36.9 °C (T50) and 36.6 °C (T60), in MF group from 38.3 °C (T0) to 37.7 °C (T30), 37.5 °C (T40), 37.2 °C (T50) and 37.1 °C (T60) and in AF group from 37.7 °C (T0) to 37.3 °C (T40), 37.2 °C (T50) and 37.1 °C (T60). The T-Rec significantly decreased in F group from 38.0 °C (T0) to 37.4 °C (T40), 37.2 °C (T50) and 36.9 °C (T60), in MF group from 38.3 °C (T0) to 37.5 °C (T50) and 37.4 °C (T60) and in AF group from 38.2 °C (T0) to 37.6 °C (T40), 37.5 °C (T50) and 37.4 °C (T60). Conclusions and clinical relevancePremedication with fentanyl, medetomidine–fentanyl or acepromazine–fentanyl in the doses used decreased the T-Oeso and T-Rec. The T-Oeso at the beginning of anaesthesia was higher after premedication with medetomidine–fentanyl. However, this difference was not clinically significant.