Clinical investigation of remifentanil and propofol for the total intravenous anaesthesia of dogs

Fifteen adult dogs underwent elective ovariectomy. They were premedicated with 0(.)5 mg/kg methadone and 0(.)05 mg/kg(-1) atropine administered intramuscularly, and anaesthesia was induced with propofol and maintained with intravenous infusions of remifentanil at 0-6 mu g/kg/minute and propofol; the mean (sd) rate of infusion of propofol throughout the period of anaesthesia was 0(.)33 (0(.)03) mg/kg/minute. The dogs were ventilated continuously with oxygen while they were anaesthetised. Their haemodynamic parameters were clinically acceptable during the period of anaesthesia. Two dogs received additional atropine to correct bradycardias of less than 60 bpm and several dogs received additional boluses of remifentanil or propofol to maintain an adequate depth of anaesthesia, as determined by a clinical assessment. The mean (range) time to the return of spontaneous respiration after stopping the remifentanil infusion was 11(.)1 (6(.)0 to 17(.)0) minutes, and the mean (range) time to the dogs standing was 38(.)0 (20(.)0 to 80(.)0) minutes. The quality of recovery was good in 12 of the dogs, two showed mild excitation in the immediate postoperative period and the other dog required additional analgesia with methadone.