Evaluation of BAM (butorphanol–azaperone–medetomidine) in captive African lion ( Panthera leo ) immobilization

The combination of butorphanol, azaperone and medetomidine (BAM) with subsequent antagonism by naltrexone-yohimbine or naltrexone-atipamezole was evaluated for reversible immobilization of captive African lions (Panthea leo).Prospective, clinical trial.Twenty lions, 11 males and nine females, weighing 38-284 kg were immobilized in South Africa.The BAM volume dose rate administered was 0.005-0.008 mL kg-1 (0.6 mL 100 kg-1). Physiologic variables were recorded every 5 minutes. Four arterial blood samples were collected from all animals at 20, 30, 40 and 50 minutes after immobilization for analysis of blood-gases and acid-base status.The actual doses administered were as follows: butorphanol, 0.18±0.03 mg kg-1; azaperone, 0.07±0.01 mg kg-1; and medetomidine, 0.07±0.01 mg kg-1. The inductions were calm and smooth, and induction time ranged from 4 to 10 minutes (7±2 minutes). The amount of time needed to work with each lion was 70 minutes, and no additional drug doses were needed. Heart rate (40±8 beats minute-1) and respiratory frequency (15±4 breaths minute-1) were stable throughout immobilization. The mean arterial blood pressure of all animals was stable but elevated (142±16 mmHg). The rectal temperature slightly increased over time but remained within acceptable range. The recovery time was significantly shorter when using naltrexone and atipamezole (9±1 minutes) compared to using naltrexone and yohimbine (22±7 minutes).The BAM combination proved to be reliable for general veterinary anaesthesia in lions. During anaesthesia, minor veterinary procedures such a blood collection, intubation, vaccination and collaring could safely be performed with no additional dosing required.