REVERSIBLE IMMOBILIZATION OF FREE-RANGING POLAR BEARS WITH MEDETOMIDINE-ZOLAZEPAM-TILETAMINE AND ATIPAMEZOLE

The objective of this study was to determine if the potent alpha(2) ag onist, medetomidine, and its specific antagonist, atipamezole, could b e effectively used to immobilize polar bears (Ursus maritimus). Specif ically, our goal was to develop a drug combination containing medetomi dine that addressed some of the problems such as prolonged recovery ti me, non-reversibility, and poor analgesia that have been identified wi th the currently preferred drug combination, zolazepam-tiletamine (Tel azol(R) or Zoletil(R)). During 1995 and 1996, 51 free-ranging polar be ars along the western coast of Hudson Bay, Canada, were immobilized wi th a combination of medetomidine, zolazepam, and tiletamine (MZT). Imm obilization with MZT was characterized by a short induction time, low volume, reliable and predictable immobilization and reversibility, ade quate analgesia, and relative safety in handling for field personnel. Few adverse physiological effects were observed in any target animals with the exception of a single bear which convulsed and died shortly a fter it was reversed from anesthesia with atipamezole. We conclude tha t MZT is an effective drug combination for immobilizing polar bears. H owever, because of an unexplained mortality, further investigation of the physiological effects of MZT and atipamezole is warranted.