Evaluation of medetomidine-ketamine and atipamezole for reversible anesthesia of free-ranging gray wolves (Canis lupus).

Twenty-eight anesthetic events were carried out on 24 free-ranging Scandinavian gray wolves (Canis lupus) by darting from a helicopter with 5 mg medetomidine and 250 mg ketamine during winter in 2002 and 2003. Mean±SD doses were 0.162±0.008 mg medetomidine/kg and 8.1±0.4 mg ketamine/kg in juveniles (7-10 mo old) and 0.110±0.014 mg medetomidine/kg and 5.7±0.5 mg ketamine/kg in adults (>19 mo old). Mean±SD induction time was shorter (P<0.01) in juveniles (2.3±0.8 min) than in adults (4.1±0.6 min). In 26 cases, the animals were completely immobilized after one dart. Muscle relaxation was good, palpebral reflexes were present, and there were no reactions to handling or minor painful stimuli. Mild to severe hyperthermia was detected in 14/28 anesthetic events. Atipamezole (5 mg per mg medetomidine) was injected intramuscularly for reversal 98±28 and 94±40 min after darting in juveniles and adults, respectively. Mean±SD time from administration of atipamezole to coordinated walking was 38±20 min in juveniles and 41±21 min in adults. Recovery was uneventful in 25 anesthetic events, although vomiting was observed in five animals. One adult that did not respond to atipamezole was given intravenous fluids and was fully recovered 8 hr after darting. Two animals died 7-9 hr after capture, despite intensive care. Both mortalities were attributed to shock and circulatory collapse following stress-induced hyperthermia. Although effective, this combination cannot be recommended for darting free-ranging wolves from helicopter at the doses presented here because of the severe hyperthermia seen in several wolves, two deaths, and prolonged recovery in one individual.