Chemical immobilization of raccoons (Procyon lotor) with ketamine-medetomidine mixture and reversal with atipamezole

Safe and reliable capture techniques for wild animals are important for ecologic studies and management operations. We assessed the efficiency of ketamine-medetomidine (K:M) injection and reversal with atipamezole. We anesthetized 67 raccoons (Procyon lotor; 34 males, 33 females) 103 times (individuals captured between one and five times) from April 2009-October 2010 in Mont-Orford Provincial Park, Quebec, Canada. We administered a 1:1 mixture by volume of ketamine and medetomidine by intramuscular injection. Mean (±SD) induction times for males and females were 6.1±2.8 and 6.6±3.7 min, respectively. Mean induction time was 2 min longer for juveniles than for adults (7.8±3.9 and 5.8±2.9 min, respectively) and longer in autumn than in spring for adults (7.7±3.8 and 5.4±2.9 min, respectively). Recovery time after administration of atipamezole was 9.6±3.8 and 8.4±4.4 min for males and females, respectively. Recovery time was longer in spring than in autumn (10.2±4 and 7.4±3.8 min, respectively) for adults. Induction time increased by 166% after five captures of the same individual. Immobilization did not affect body mass, adult survival, or female reproductive success. We suggest the K:M mixture used is a safe and reliable method for anesthetizing raccoons in field conditions.