Tolazoline antagonises ketamine-xylazine anaesthesia in an endangered Black buck (Antilope cervicapra)

Abstract

Seventy-seven anaesthetic events were carried out in 22 captive adult Black bucks (Antilope cervicapra) of either sex with a combination of 2 mg kg⁻¹ ketamine hydrochloride with 0.25 mg kg⁻¹ xylazine hydrochloride using a dart delivered from a blowpipe. Randomised anaesthetised animals received an intravenous injection of either yohimbine hydrochloride (0.125 or 0.25 mg kg⁻¹) or tolazoline hydrochloride (1 or 2 mg kg⁻¹) after 30-40 min of anaesthesia to antagonise the anaesthetic effects. Ketamine-xylazine induced smooth, rapid and reliable anaesthesia within 5-7 min of darting with no clinical adverse effects and causalities during or post-anaesthesia. Yohimbine failed to antagonise the anaesthetic effects of ketamine-xylazine in the Black buck. On the other hand, tolazoline was found to be very effective in hastening recovery in dose-dependent manner within 0.5-1.5 min. This study documents the first report of ketamine-xylazine anaesthesia and its antagonism by tolazoline in captive Black buck.