Butorphanol, Azaperone, Medetomidine Anesthesia in Free-Ranging White-Tailed Deer (Odocoileus virginianus) Using Radiotransmitter Darts
Free-ranging white-tailed deer (Odocoileus virginianus) were successfully immobilized using a combination of butorphanol (0.58±0.1 mg/kg), azaperone (0.37±0.06 mg/kg), and medetomidine (0.19±0.03 mg/kg) administered by remote injection of radiotelemetry Pneu-Darts (Pneu-Dart, Inc., Williamsport, Pennsylvania, USA) from hunting blinds between November 2006 and May 2007. Mean times to locate deer, to induction, and to recovery were recorded. Physiologic monitoring (heart rate, respiratory rate, rectal temperature, end-tidal CO2, oxyhemoglobin saturation, and indirect arterial blood pressure) was initiated upon securing the animal, and continued 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 based on arterial oxygen saturation and end-tidal CO2 values occurred in some animals. Muscle relaxation and anesthetic plane were adequate for completion of all procedures (weight, venipuncture, morphometrics, ± brief transport); two deer required intravenous butorphanol supplementation to achieve light anesthesia (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. Overall efficacy of Pneu-Darts (full drug delivery; tracking reliability; maintained intramuscularly until animal located) was 65%. Negative attributes included time delay required between darting and locating animal to ensure full anesthetic effect; dart failure. No known mortalities occurred as a result of the study. This combination provided safe, reliable, short-term immobilization of free-ranging white-tailed deer. Evaluation for use in field immobilizations of other cervids is warranted.
The authors thank Wildlife Pharmaceuticals, Inc. for supplying the immobilizing agents; Kristine Polk, Lara Metrione, Rhett Walker, Shannon McCarthy, Lynn Proenza, Hector Gutierrez, Tina Bruaset, Katryna (Katie) Fleer, Judilee Marrow, K. Marie Labak, and Linda Penfold at White Oak Conservation Center for assistance in deer feeding, tracking, restraint, and data collection.