Urethane-acepromazine: a novel method of administering parenteral anesthesia in the rabbit.

Stable long-term anesthesia in the rabbit (greater than 8 hr) has been achieved by the administration of urethane and acepromazine. Twenty-five healthy male New Zealand white rabbits weighing 2 to 4 kg were used for this study. Two groups of animals were studied. The first group of 11 rabbits received urethane (1.0 g/kg) and acepromazine (1 mg/0.46 kg). This resulted in stable light plane anesthesia for 13.5 +/- 4.5 hr (mean + S.D.). The second group of 14 rabbits received urethane (1.3 g/kg) and acepromazine (1 mg/0.46 kg) which resulted in deep plane anesthesia for 23.0 +/- 4 hr. Heart rate and respiratory rate remained stable throughout the entire period and all animals were alert and without any observable side effects by 48 +/- 3 hr. This study indicates that the combination of urethane-acepromazine is a safe and reproducible parenteral anesthetic that may be used in studies of long duration in rabbits.