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.