Abstract

Chemical restraint (general anesthesia and/or deep sedation) is often used to facilitate collection of samples during wildlife research. This is especially true for large animals that might otherwise injure themselves or the research staff during manual restraint and for repeated, prolonged or invasive sampling. At the Alaska SeaLife Center, 72 juvenile, subadult and adult Steller sea lions (Eumetopias jubatus) have been repeatedly anesthetized as necessary during research and veterinary procedures over the past 15 years. Three of these animals (2 adult females and one adult male) have been anesthetized over 90 times each between 1998 and 2013.

One of three anesthetic protocols was typically employed depending on the size of the sea lion and whether physical restraint or operant conditioning was used during induction. Animals under 220 kg, or those behaviorally trained to co-operate for the procedure, were held in specially designed cages without premedication. Anesthesia was induced via face mask using isoflurane gas in medical oxygen followed as necessary by endotracheal intubation for continued delivery of isoflurane for prolonged procedures. An adult male, whose weight ranged seasonally up to 970 kg, received premedication by intramuscular injections under behavioral control. Atropine and a commercial preparation of tiletamine and zolazepam (Telazol©) or a combination of specially formulated medetomidine and midazolam were used for sedation to facilitate masking or intubation with isoflurane. Medetomidine was frequently reversed using atipamezole to shorten the recovery from that drug but reversal of benzodiazepines was not typically needed.

Veterinary staff monitored the sea lions throughout all anesthesias and vital signs (rectal temperature, heart and respiratory rate, oxygen saturation and end tidal carbon dioxide) were recorded using manual and electronic monitoring. Time to induction, time to recovery, quality of anesthesia and recovery, types of procedures performed and any complications were also noted. Health monitoring of the sea lions included periodic complete blood cell counts and serum chemistry testing as well as behavioral observations and occasional hormone evaluations conducted as part of the research protocols.

While any chemical restraint has the potential for adverse effects, no significant complications or detrimental events have occurred during any of these procedures.

Acknowledgements

The authors thank the Husbandry, Veterinary, and Research staff members at the Alaska SeaLife Center who provided care for, and assisted with the anesthesias of, the Steller sea lions in this report. These animals were held under NOAA Permits 881-1443, 881-1745, 14334, 881-1668 and 14335. The anesthetic procedures required to perform research and the research protocols were approved under appropriate Alaska SeaLife Center IACUC Assurances of Animal Care.

* Presenting author