Document Type

Student Research Paper


Spring 2021

Academic Department


Faculty Advisor(s)

Dr. Debra Wohl


Optimal wildlife anesthetic protocols should induce rapid immobilization, allow for rapid recovery, and provide a wide margin of safety. The ketamine and xylazine (KX) anesthetic protocol is commonly used in chemical immobilizations of Ursus americanus (American black bear); however, some biologists report unreliability due to inconsistent recovery times and side effects such as convulsions, sudden arousals, and hyperthermia. In recent years, some biologists have employed the ketamine, xylazine and Telazol® (TKX) anesthetic protocol, which requires relatively lower dose of ketamine and telazol when administered together. Black bears drastically decrease their vital and metabolic rates during hibernation as compared to the active and hyperphagic states. This scenario could alter the efficacy of anesthetic agents during different bear physiological stages. Unfortunately, there is no evidence on whether TKX performs better than the KX protocol under any bear physiological stage. Thus, our objective was to compare the chemical immobilization performance of both KX and TKX protocols in bears housed at Virginia Tech’s Black Bear Research Center. Protocol performance was assessed through vital sign frequencies, induction time, and recovery time in 16 bears (11F and 5M). We used linear models to compare variables across different metabolic states. We found more consistent vitals using TKX compared to the KX protocol. Induction times remained similar in pre-hibernation ~10min, yet TKX produced longer inductions (8min) than KX during hibernation, and TKX produced shorter inductions (21min) than KX post-hibernation. Route of reversal agent administration influenced recovery times regardless of anesthetic protocol or physiological stage, where intravenous was 21min faster than intramuscular, and 29min less than per rectum. Both TKX and KX produced immobilization lasting at least 100min. We recommend using KX if immobilizing bears during hibernation and administering TKX during the pre and post hibernation states, as it produces shorter induction times and less variable bear vital signs.


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Biology Commons