Changes in tracheal, oesophageal and rectal temperature over 60 minutes anaesthesia in non-heated dogs, spontaneously breathing or mechanically ventilated

The objective of this prospective randomised clinical study was to determine the differences in the tracheal, oesophageal and rectal temperature in spontaneously breathing or mechanically ventilated dogs. A total of thirty dogs were allocated to the SPO-group breathing spontaneously (n = 15) or the MEC-group ventilated mechanically (n = 15). Anaesthesia was established using a medetomidine-butorphanol-propofol-isoflurane combination. The tracheal (T-Tra), oesophageal (T-Oes), rectal (T-Rec), inspired gas (T-Gas), room (T-Room) temperatures, respiratory frequency (fR), heart rate (HR), mean arterial pressure (MAP) and end-tidal carbon dioxide concentration (ETCO2) were measured after connecting to a re-breathing system (baseline) and subsequently in 10-minute intervals for 60 minutes. The data were analysed using ANOVA and Steel-Dwass tests (P < 0.05). In the SPO-group, the T-Tra, was significantly lower at T30, T40, T50, T60, the T-Oes and T-Rec at T40, T50, T60, compared to the baseline. In the MEC-group, the T-Tra and T-Oes was significantly lower at T30, T40, T50, T60, the T-Rec at T40, T50, T60, compared to the baseline. In the SPO-group, the fR was significantly lower for all the times and the ETCO2 higher at T10, T20, T30, T40, T50 compared to the MEC-group. No other differences were detected. During anaesthesia, there is a comparable decrease in body temperatures, regardless of whether the dogs are breathing spontaneously or ventilated mechanically.