Evaluation of the efficacy and safety of a modified anesthetic protocol using dexmedetomidine, midazolam, and butorphanol in mice

Abstract

We aimed to evaluate the efficacy and safety of a modified injectable anesthesia protocol combining dexmedetomidine, midazolam, and butorphanol (dMMB) compared with the conventional medetomidine-based protocol (MMB) in C57BL/6J mice. Animals were assigned to three groups (n=5 per group for each sex): MMB (0.5/4.0/5.0), dMMB (0.25/4.0/5.0), and dMMB (0.1/6.0/10.0) mg/kg. We assessed anesthetic induction and recovery times, depth scores, heart rate, SpO₂, and body temperature, and administered atipamezole 40 min post-anesthesia to evaluate temperature recovery. Blood glucose levels were also measured. Both dMMB protocols produced anesthetic effects comparable to MMB, but recovery was significantly faster than MMB. Duration of surgical anesthesia in males (mean ± 95% confidence interval) was 141 ± 11 min for MMB, 112 ± 8 min for dMMB (0.25/4.0/5.0), and 89 ± 10 min for dMMB (0.1/6.0/10.0). In females, durations were 109 ± 43 min, 76 ± 12 min, and 78 ± 16 min, respectively. In addition, hypothermia was less severe, particularly with the lowest dexmedetomidine dose (0.1/6.0/10.0). Furthermore, females had a significantly shorter duration of surgical anesthesia than males. Blood glucose levels increased under all anesthetic protocols, with males showing higher values than females, while no significant differences among anesthetic protocols were detected in either sex. No additional adverse effects were observed. These findings indicated that low-dose dexmedetomidine-based anesthesia provides effective sedation while improving safety by reducing hypothermia and facilitating rapid recovery.