Induction of anaesthesia with alfaxalone or propofol before isoflurane maintenance in cats.

Thirty-nine healthy cats that were presented for ovariohysterectomy received intramuscular acepromazine (0.05 mg/kg) and subcutaneous meloxicam (0.3 mg/kg) as preanaesthetic medication. They were then randomly assigned to receive either propofol or alfaxalone by intravenous injection for induction of anaesthesia, administered to effect until tracheal intubation was possible. Anaesthesia was maintained with isoflurane in oxygen. Cardiorespiratory variables were measured before induction and every five minutes throughout anaesthesia. The recovery times and quality of recovery were also recorded. Data relating to one cat were omitted because it was found to be pregnant. The mean (sd) induction doses were 4.7 (1.2) mg/kg for alfaxalone and 7.5 (2.0) mg/kg for propofol. Postinduction apnoea was not observed. There were no significant differences in cardiorespiratory variables between the alfaxalone group (mean pulse rate [PR] 155 [18]) bpm, Doppler arterial blood pressure [DBP] 73 [6] mmHg, respiratory rate [RR] 31 [8] breaths/minute, end-tidal carbon dioxide partial pressure [PECO(2)] 3.7 [0.8] kPa) and the propofol group (PR 147 [16] bpm, DBP 77 [12] mmHg, RR 32 [8] breaths/minute, PECO(2) 3.7 [0.5] kPa). Recovery times were very similar and the quality of recovery was considered fair or good in most cats in both groups. The induction of anaesthesia, the cardiorespiratory variables and the recovery were clinically acceptable and similar after induction with either alfaxalone or propofol.