Abstract

Alfaxalone (Alfaxan®, Vétoquinol Jurox, London, UK, 10 mg/ml) is a well studied, rapid acting neuroanesthetic induction agent that binds to gamma-aminobutyric acid receptors following intravenous or intramuscular injection.^1-7 Currently, there are no reports of its use in marine mammals.

Following manual capture, alfaxalone was administered (2.5 mg/kg, i.m.) to six female Peruvian fur seals (Arctocephalus australis) to perform health assessments at the Punta San Juan reserve (15°22'S, 75°12'W). Mean time to initial effect was 7 min and resulted in deep sedation adequate for obtaining samples (blood, skin biopsy, orifice swabs) and measurements (morphometrics, ocular pressures). Flipper tag placement and tooth extraction (with a lidocaine nerve block) resulted in mild-moderate responses (movement and/or vocalization). All animals maintained normal spontaneous respiration rates. Arterial blood gas analysis consistently revealed mild hypoxemia, which was attributed to decreased ventilation volume and was overcome with supplemental oxygen (demand valve attached to a tight sealing nose cone). Anesthetic duration was fairly reliable (mean time to spontaneous and coordinated movement was 54 min and 59 min, respectively). Mild to moderate muscle fasciculation that was exacerbated by stimuli was noted in several animals. No other side effects were observed.

Administration at 2 mg/kg (n = 1) resulted in inadequate sedation. At 3 mg/kg (n = 1), a prolonged recovery time and severe muscle tremors were noted. Combination with another drug may ultimately yield the best results. Alfaxalone with midazolam (2 mg/kg and 0.2 mg/kg respectively, i.m., n = 1) subjectively resulted in a smoother anesthetic plane and improved recovery (characteristics and duration). Alfaxalone appears to be a safe and reliable anesthetic induction agent in A. australis and warrants further investigation.

Acknowledgements

The authors thank all persons involved with this field project, with specific thanks to Marco Cardeña, Franco Garcia, Matt Allender, and Kate Sladek. Special thanks to Dr. Patricia Majluf for her long-standing commitment to conservation of Punta San Juan's wildlife. Funding for this project was generously provided by the Chicago Zoological Society, the Chicago Board of Trade Endangered Species Fund, and Oceans of Fun.

* Presenting author

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