Thiopentone in Combination with Xylazine: An Experimental Investigation for Induction of Surgical Anesthesia and Safe Recovery in Experimental Rats

Introduction: Achieving reliable anesthesia induction and rapid postoperative recovery are crucial aspects of animal research, particularly in small experimental animals. Thiopentone is still a widely used anesthetic drug, but its safety is a primary concern in delivering a safe dose to experimental animals. However, the use of thiopentone in combination with xylazine for surgical procedures in small experimental animals remains underexplored. Therefore, this study assesses the efficacy and safety of combining thiopentone and xylazine for inducing anesthesia and facilitating recovery in Sprague-Dawley rats (n = 6). Methods: Several sedatives and anesthetic agents, with diazepam (A), thiopentone (B), and xylazine (C), were evaluated alone and in combinations (AB, AC, BC, ABC). Rectal temperature, pulse rate, onset of anesthesia, and sedation duration were recorded before and after the administration. Results: Thiopentone (45 mg/kg) alone caused significant declines in vital parameters and mortality. However, the BC combination (thiopentone 35 mg/kg + xylazine 7 mg/kg) induced rapid and prolonged anesthesia without mortality, mitigating thiopentone-induced hypothermia, bradycardia, and respiratory depression. This combination was further validated in 24 rats undergoing stereotaxic surgery, demonstrating its effectiveness and safety. Discussion: The results demonstrated that while thiopentone monotherapy led to significant adverse effects, including hypothermia, decreased pulse rate, and respiratory depression, the combination of thiopentone with xylazine, particularly at specific doses, showed promising outcomes in mitigating these side effects. Conclusion: The data obtained from the present study suggest that a combination of thiopentone (35 mg/kg) with xylazine (7 mg/kg) may represent the optimal surgical dose for inducing surgical anesthesia in rats.