Abstract

The Alaska SeaLife Center completed eighty-three successful sedation procedures from 2014–2019 with sick seals handled during rehabilitation and healthy seals handled for sampling and diagnostic procedures in a clinical setting in Seward, AK. Sedation protocols are reported for Alaskan spotted (Phoca largha), ringed (Pusa hispida), and bearded (Erignathus barbatus) seals treated in a clinical setting at the Alaska SeaLife Center, Seward, AK. Combinations of midazolam hydrochloride 5 mg/mL (AKORN Inc, Lake Forest, IL) and butorphanol tartrate 10 mg/mL (Patterson Veterinary, Greeley, CO) delivered via intramuscular injection were used to induce sedation for up to 2.5 hours. In cases of general anesthesia following initial sedation, a single lumen 20 g, 13 cm catheter¹ (central venous catheter J1040, Jorgensen Laboratories, Inc, Loveland, CO) was placed within the dorsal sinus, and isoflurane gas anesthesia (Patterson Veterinary, Greeley, CO) was administered at vaporizer setting of 0.5–2.0% via endotracheal tube.² Typically, sedation was discontinued with an intramuscular injection of naltrexone 50 mg/mL (ZooPharm, Laramie, WY) at a dosage range of 1.0–2.0 mg per 1 mg of butorphanol. This reversal agent allowed for a smooth, calm recovery and immediate improvement in respiratory rate and oxygenation. The development of chemical sedation protocols in well controlled, clinical settings has enabled safe and predictable examination, sampling, and diagnostics of phocid seals, including Arctic species for which few veterinary data are available.

Acknowledgements

The authors thank the veterinary and husbandry teams at the Alaska SeaLife Center for their valuable contributions to this project, and the staff of the PHOCAS research program at the Alaska SeaLife Center and Long Marine Laboratory, especially Dr. David Casper. Additional acknowledgement is extended to Dr. Paolo Martelli, and the Marine Mammal team at Ocean Park, Hong Kong for their initial work with reversible sedation in spotted seals. Rescue and rehabilitation activities were authorized under NOAA MMHSRP #18786-02 and Stranding Agreement SA-AKR-2019-01, and MMHSRP MMPA/ESA #18786-04. Resident animals included in this report were maintained under NOAA marine mammal research permit #18902.

Literature Cited

1.  Goertz CEC, Gray M, Tuomi P. 2008. Long term catheters for phocids undergoing rehabilitation. Proceedings of the American Association of Zoo Veterinarians, Los Angeles, CA.

2.  Hermann-Sorensen H, Thometz NM, Woodie K, Dennison-Gibby S, Reichmuth C. 2021. In vivo measurement of lung volume in ringed seals: insights from biomedical imaging. Journal of Experimental Biology 224: jeb235507.