Abstract

Multiple combinations of injectable and inhalant anesthetics have been used on free-ranging and managed pinnipeds.^1,2,3,4,5 While injectable anesthetics may be remotely delivered and have specific reversal agents, inhalant anesthetics can be titrated to effect and yield rapid induction and recovery. This study compared the use of isoflurane, sevoflurane, and desflurane in a managed population of Steller sea lions (Eumetopias jubatus). Eight female sea lions were induced under voluntary control (facemask) with or without a premedication (diazepam), and were maintained with one of the three gases via facemask or endotracheal tube (ETT). Blood gases were obtained at full induction and after 20 minutes. End-tidal and inspired oxygen, carbon dioxide, and anesthetic agents were measured. Induction and recovery times for desflurane were significantly shorter than those for isoflurane (p=0.001 and p=0.036) and sevoflurane (p=0.032 and p=0.03). In addition, maintenance on a mask rather than an ETT yielded a shorter recovery time (p=0.02). The pCO2 at induction was significantly lower in animals with no premedication (60.37 mm Hg) compared to with premedication (67.42 mm Hg) (p=0.003), and those that were given premedication also had significantly lower lactate and glucose levels (p=0.001 and p<0.0001). This study is consistent with studies in other species that report a significantly shorter induction and recovery time using desflurane in comparison with isoflurane and sevoflurane.^6,7,8,9,10 However, practicality of cost and need for access to electricity may limit the use of desflurane in the field.

Acknowledgements

The authors wish to thank the animal care staff (Danielle Hyson, Malgosia Kaczmarska, Billy Lasby, Nigel Walker) and veterinary technicians (Sion Cahoon, Chelsea DeColle) of the Vancouver Aquarium as well as the research students (Brianna Cairns, Aaron Purdy) and technicians (Rebecca Barrick, Rob Marshall) of the University of British Columbia Marine Mammal Research Unit. Dr. James Bailey also assisted with additions to study design.

* Presenting author

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