Immobilization of Grizzly Bears with Tiletamine Hydrochloride and Zolazepam Hydrochloride

Abstract

We successfully immobilized 185 grizzly bears (Ursus arctos horribilis) with tiletamine hydrochloride (HC1) and zolazepam HCl during May-June 1986-87. One hundred eighty bears were captured in several areas in Alaska by darting from a helicopter; 5 were immobilized from traps or snares in Banff National Park in Alberta, Canada. Use of the recommended dose for immobilizing grizzly bears (7-9 mg/ kg) resulted in a mean induction time of 4.1 + 1.8 (SD) minutes and a safe handling period of 45-75 minutes. Tiletamine HCl/zolazepam HCI was an excellent drug for immobilizing grizzly bears because of rapid induction, timely and predictable recovery, wide safety margin, and few adverse side effects. J. WILDL. MANAGE. 53(4):978-981 A 1:1 mixture of tiletamine HCI and zolazepam HCI (TZHCL) (Telazol?, A. H. Robins Co., Richmond, Va.; Zoletil?, Reading Lab., L'Hayles-Roses, France) has been used to immobilize several wildlife species (Schobert 1987). Appropriate dosages have been established for freeranging polar (Ursus maritimus) (Haigh et al. 1985, Stirling et al. 1985) and black bears (Ursus americanus) (Stewart et al. 1980). However, the literature only mentions its use on captive grizzly bears (Gray et al. 1974, Bush et al. 1980). Tiletamine HCI is a cyclohexamine dissociative anesthetic agent, with a pharmacological action characterized by cataleptoid anesthesia, analgesia, normal pharyngeal-laryngeal reflexes, and muscle rigidity. Eyes normally remain open with the pupils dilated; however, corneal reflex is maintained. Zolazepam HCI is a diazepinone tranquilizer with central nervous system depressant actions characterized by muscle relaxation, anticonvulsant, and hypnosis (A. H. Robins Co., Telazol?, package insert, Richmond, Va., 1987). Combining the 2 products results in the manifestation of desirable characteristics of each while minimizing undesirable side effects. Even though TZHCL is classified as a general anesthetic, the eyelids usually remain open and, at lower dosages: corneal, palpebral, laryngeal, pharyngeal, pedal, and pinnal reflexes persist. The pedal and pinnal reflexes diminish at higher dosages (Gray et al. 1974). The objective of our study was to establish effective dosages of TZHCL and determine the benefits and disadvantages associated with its use to immobilize free-ranging grizzly bears. We thank S. D. Miller and B. H. Campbell for providing additional opportunity for testing this drug. They also assisted in data collection and manuscript review. Funding was provided by the State of Alaska, National Park Service, and several Federal Aid to Wildlife Restoration