General anesthesia in two Asian elephants (Elephas maximus)using combination of medetomidine hydrochloride and etorphine hydrochloride

Abstract

General anesthesia was performed in two Asian elephants by using the combination 5.5 - 6.0 mg medetomidine hydrochloride (median = 2.29 ± 0.064 mg/kg) and 4.0 - 5.0 mg etorphine hydrochloride (median = 1.84 ± 0.088 mg/kg) via intramuscular administration. The data was collected and analyzed during five times of general anesthesia procedures. Onset time of light sedation effect presented in 2 - 8 minutes after drug administration; the movement of the ears and tail reduced after 2 - 8 minutes, penis or vulva relaxation occurred after 5 - 20 minutes, eyelids were closed after 3 - 15 minutes, relaxation of the trunk after 6 - 27 minutes, ataxia after 6 - 22 minute, and animal presented lateral recumbency posture after 7 - 30 minutes of drug administration. A combination of atipamezole hydrochloride 28 – 30 mg (median = 11.64 ± 0.39 mg/kg) and naltrexone 250 – 330 mg (median = 0.11 ± 0.018 mg/kg) was given as a reversal agent, which was five times the amount of medetomidine hydrochloride and fifty times the amount of etorphine hydrochloride respectively. Recovery effect started from open eyelids 0.5 - 4 minutes, trunk movement 1 - 4 minutes, head lifting 2 - 7 minutes, adjusted to standing position 3 - 25 minutes, and completed full recovery 10 - 142 minutes after administration. This study showed effects of the combination of 2.29 ± 0.064 mg/kg medetomidine hydrochloride and 1.84 ± 0.088 mg/kg etorphine hydrochloride in general anesthesia of 2 domestic Asian elephants. The drug combination is effective to induce animal recumbency within 24 minutes.