Total intravenous anaesthesia maintenance with an infusion of butorphanol, ketamine and guaifenesin in two greater one-horned rhinoceros (Rhinoceros unicornis)

This report describes the use of an ultrapotent, opioid-free anaesthesia with an infusion of butorphanol, ketamine and guaifenesin in two captive adult male greater one-horned rhinoceros (Rhinoceros unicornis). Animals were premedicated intramuscularly with azaperone (0.05 mg/kg), butorphanol tartrate (0.05 and 0.02 mg/kg, respectively) and an α2-agonist (detomidine 0.02 mg/kg and medetomidine 0.01 mg/kg, respectively). Once sternolaterally recumbent, rhinoceros were induced with intravenous ketamine (0.02 and 0.05 mg/kg, respectively) and midazolam (7.0 and 8.0 μg/kg, respectively). Intravenous infusions of guaifenesin (15.1 and 25 mg/kg/h, respectively) and of ketamine (22.5 and 29.1 μg/kg/h, respectively) and butorphanol (15.7 and 20.3 μg/kg/h, respectively), allowed stable anaesthesia maintenance for dental procedures to take place. Supplemental boluses of ketamine and α2-agonist were required during noxious stimulation in both cases. Animals were reversed with intramuscular atipamezole (0.07–0.08 mg/kg) and naltrexone (0.06–0.08 mg/kg), with or without flumazenil (0.10 μg/kg), allowing smooth and quick recovery.