Abstract

An oral carfentanil anesthetic protocol, with reversal by intranasal naltrexone, was evaluated as a new method for immobilizing lion-tailed macaques (Macaca silenus). Five adult macaques were given carfentanil-laced marshmallows. At doses of 60 mg/kg, anesthesia occurred within 12 minutes of consumption and was followed within 4 minutes by profound cardiopulmonary depression. Both apnea and bradycardia were restored within 1 minute by administering intranasal (IN) naltrexone (30 mg/kg). A low carfentanil dose (0.05 mg/kg) did not induce adequate anesthesia. A carfentanil dose of 0.1 mg/kg produced immobilization without toxicity within 30 minutes and was readily reversed using less naltrexone (3 mg/kg IN). This data demonstrates that oral carfentanil (0.1 mg/kg) effectively immobilizes adult lion-tailed macaques, indicates that this species is more sensitive to carfentanil toxicity than are other non-human primates, and shows that intranasal naltrexone rapidly reverses both immobilization and toxicity induced by carfentanil. The protocol was also successfully used in a field situation to capture and recover a spider monkey (Ateles geoffroyi).