Immobilization of Clover-trapped White-tailed Deer, Odocoileus virginianus, with Medetomidine and Ketamine, and Antagonism with Atipamezole

Abstract

We evaluated the effectiveness of immobilizing Clover-trapped White-tailed Deer (Odocoileus virginanus) with medetomidine hydrochloride (HCl) and ketamine HCl during winter and summer by monitoring immobilization intervals and vital signs. In winter, we captured deer in Clover traps in 1 4-ha research enclosure for relocation to another on-site enclosure (n = 5). In summer, we captured free-ranging deer in Clover traps to attach radio-collars (n = 4). We administered an estimated 0.055 mg/kg medetomidine HCl and 2.5 mg/kg ketamine HCl to adult (> 1.5 years of age) deer and 0.06 mg/kg medetomidine HCl and 2.5 mg/kg ketamine HCl to subadult (< 1.5 years of age) deer. We used an intramuscular injection of atipamezole HCl as the antagonist at a rate of 0.275 mg/kg for adults and 0.3 mg/kg for subadults > 30 minutes post-induction. Mean induction time in winter was 11.2 minutes (SE = 2.5, range = 5.4 - 24.2) and 6.5 minutes (SE = 0.8, range = 6.2 - 7.5) in summer. After atipamezole HCl injection, the mean time to walking was 17.1 minutes (SE = 3.5, range = 7.5 - 41.5 minutes) in winter and 11.3 minutes (SE = 3.8, range = 4.7 - 13.5) in summer. Rectal temperature was relatively constant throughout immobilization; however rectal temperatures of 5 deer (n = 3 in winter; n = 2 in summer) exceeded 40^oC, a sign of hyperthermia. Respiration rate and pulse rate peaked at about 20 minutes post-medetomidine HCl and ketamine HCl injection, then generally declined thereafter. No mortalities were observed in our study. Medetomidine HCl and ketamine HCl doses for Clover-trapped White-tailed Deer provided satisfactory induction times, sufficient level of anesthesia for short-distance relocation or radio-collar attachment, and were effectively reversed with an IM injection of atipamezole HCl.