Intranasal naltrexone and atipamezole for reversal of white-tailed deer immobilized with carfentanil and medetomidine.

Carfentanil and medetomidine were used to immobilize 8 captive female white-tailed deer (Odocoileus virginianus) using mean dosages [+/- standard deviation (s)] of 14.2 +/- 1.11 microg/kg carfentanil and 17.8 +/- 2.03 microg/kg of medetomidine. Deer were reversed by intranasally or intramuscularly administered naltrexone and atipamezole. Dosages of carfentanil and medetomidine proved reliable for immobilization of most, but not all deer, with a mean induction time of 13.3 +/- 3.13 min. Effective and reliable immobilization will require higher dosages of carfentanil and possibly medetomidine than were used in this study. No significant differences in recovery times were observed for deer given reversal agents intranasally (9.45 +/- 5.37 min) versus intramuscularly (7.60 +/- 4.42 min). Naltrexone and atipamezole can be administered intranasally at 1.5 mg/kg and 0.1 mg/kg, respectively to safely and quickly reverse the effects of carfentanil and medetomidine in immobilized white-tailed deer. This route could potentially be useful for other reversal agents.