Butorphanol, azaperone, and medetomidine anesthesia in free-ranging white-tailed deer (Odocoileus virginianus) using radiotransmitter darts.

Fourteen free-ranging white-tailed deer (Odocoileus virginianus) were successfully anesthetized for a total of 15 anesthetic events using a combination of butorphanol (mean+/-SD, 0.58+/-0.1 mg/kg), azaperone (0.37+/-0.06 mg/kg), and medetomidine (0.19+/-0.03 mg/kg) (BAM) administered by radiotelemetry darts from hunting blinds between November 2006 and May 2007. Mean time to locate deer (mean+/-SD, 17. 3+/-7 min), to recumbency (21.4+/-5 min), to initiation of data acquisition (27.5+/-8 min), total down time (37+/-6 min), and average distance run (161+/-82 m) were recorded. Physiologic monitoring was done every 5 min for a total of 20 min. Arterial blood gases were collected every 10 min. Mild to moderate hypoxemia and mildly depressed ventilation occurred in some animals. Muscle relaxation and plane of anesthesia were adequate for completion of all procedures; two deer were administered intravenous butorphanol supplementation to achieve light anesthesia (mean+/-SD, 0.19 mg/kg; 0.12 mg/kg). Recovery following intramuscular administration of naltrexone (1.34+/-0.42 mg/kg; 2x butorphanol dose) and atipamezole (0.93+/-0.14 mg/kg; 5x medetomidine dose) was rapid, smooth, and complete. Mean+/-SD recovery time was 4.5+/-1.5 min. Overall efficacy of the Pneu-Dart radiotelemetry system was 65%. Negative attributes of this protocol included long induction time and dart failure. No known mortalities occurred as a result of the study. This drug combination provided safe, reliable, short-term anesthesia of free-ranging white-tailed deer. Further evaluation for use in field procedures in other cervids is warranted.