Comparison of alfaxalone and propofol administered as total intravenous anaesthesia for ovariohysterectomy in dogs

ObjectiveTo compare the anaesthetic and cardiopulmonary effects of alfaxalone with propofol when used for total intravenous anaesthesia (TIVA) during ovariohysterectomy in dogs.Study designA prospective non-blinded randomized clinical study.AnimalsFourteen healthy female crossbred bitches, aged 0.5–5 years and weight 16–42 kg.MethodsDogs were premedicated with acepromazine 0.01 mg kg^?1 and morphine 0.4 mg kg^?1. Anaesthesia was induced and maintained with either propofol or alfaxalone to effect for tracheal intubation followed by an infusion of the same agent. Dogs breathed spontaneously via a ‘circle’ circuit, with oxygen supplementation. Cardiopulmonary parameters (respiratory and heart rates, end-tidal carbon dioxide, tidal volume, and invasive blood pressures) were measured continuously and recorded at intervals related to the surgical procedure. Arterial blood samples were analysed for blood gas values. Quality of induction and recovery, and recovery times were determined. Non-parametric data were tested for significant differences between groups using the Mann–Whitney U-test and repeatedly measured data (normally distributed) for significant differences between and within groups by anova.ResultsBoth propofol and alphaxalone injection and subsequent infusions resulted in smooth, rapid induction and satisfactory maintenance of anaesthesia. Doses for induction (mean ± SD) were 5.8 ± 0.30 and 1.9 ± 0.07 mg kg^?1 and for the CRIs, 0.37 ± 0.09 and 0.11 ± 0.01 mg kg^?1 per minute for propofol and alfaxalone respectively. Median (IQR) recovery times were to sternal 45 (33–69) and 60 (46–61) and to standing 74 (69–76) and 90 (85–107) for propofol and alphaxalone respectively. Recovery quality was good. Cardiopulmonary effects did not differ between groups. Hypoventilation occurred in both groups.Conclusions and clinical relevanceFollowing premedication with acepromazine and morphine, both propofol and alphaxalone produce good quality anaesthesia adequate for ovariohysterectomy. Hypoventilation occurs suggesting a need for ventilatory support during prolonged infusion periods with either anaesthetic agent.