Intravenous sufentanil-midazolam versus sevoflurane anaesthesia in medetomidine pre-medicated Himalayan rabbits undergoing ovariohysterectomy

OBJECTIVE: To compare physiological effects of sufentanil-midazolam with sevoflurane for surgical anaesthesia in medetomidine premedicated rabbits. STUDY DESIGN: Prospective, randomized controlled experimental study. ANIMALS: Eighteen female Himalayan rabbits, weight 2.1 ± 0.1 kg. METHODS: Premedication with 0.1 mg kg(−1) medetomidine and 5 mg kg(−1) carprofen subcutaneously, was followed by intravenous anaesthetic induction with sufentanil (2.3 μg mL(−1)) and midazolam (0.45 mg mL(−1)). After endotracheal intubation, anaesthesia was maintained with sufentanil-midazolam (n = 9) or sevoflurane (n = 9). Ovariohysterectomy was performed. Intermittent positive pressure ventilation was performed as required. Physiological variables were studied perioperatively. Group means of physiologic data were generated for different anaesthetic periods. Data were compared for changes from sedation, and between groups by anova. Post-operatively, 0.05 mg kg(−1) buprenorphine was administered once and 5 mg kg(−1) carprofen once daily for 2–3 days. Rabbits were examined and weighed daily until one week after surgery. RESULTS: Smooth induction of anaesthesia was achieved within 5 minutes. Sufentanil and midazolam doses were 0.5 μg kg(−1) and 0.1 mg kg(−1), during induction and 3.9 μg kg(−1) hour(−1) and 0.8 mg kg(−1) hour(−1) during surgery, respectively. End-tidal sevoflurane concentration was 2.1% during surgery. Assisted ventilation was required in nine rabbits receiving sufentanil-midazolam and four receiving sevoflurane. There were no differences between groups in physiologic data other than arterial carbon dioxide. In rabbits receiving sevoflurane, mean arterial pressure decreased pre-surgical intervention, heart rate increased 25% during and after surgery and body weight decreased 4% post-operatively. Post-operative problems sometimes resulted from catheterization of the ear artery. CONCLUSION: Sevoflurane and sufentanil-midazolam provided surgical anaesthesia of similar quality. Arterial blood pressure was sustained during sufentanil-midazolam anaesthesia and rabbits receiving sevoflurane lost body weight following ovariohysterectomy. Mechanical ventilation was required with both anaesthetic regimens. CLINICAL RELEVANCE: Anaesthesia with sufentanil-midazolam in medetomidine premedicated healthy rabbits is useful in the clinical and the research setting, as an alternative to sevoflurane.