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Effects of midazolam on corticosterone and blood gases in spectacled eiders prior to transmitter implantation

April 8, 2021

Stress and physical exertion may affect the physiology and behavior of wildlife during and after capture, and consequently, survival following release. Such effects may reduce the quality and quantity of the data obtained from captured wildlife. We captured spectacled eiders (Somateria fischeri), a species listed as threatened under the United States Endangered Species Act, in western Alaska, USA, during spring 2018 for surgical implantation of satellite transmitters. We evaluated the efficacy of midazolam, a benzodiazepine sedative given at capture, to reduce stress and physical exertion. We dosed spectacled eiders with either midazolam (5 mg/ml,  = 2.2 mg/kg intramuscular; n = 20) or saline (0.7 ml intramuscular; n = 20) at the point of capture. We assessed sedation level and collected blood samples upon arrival to the field surgery site and at anesthetic induction. We found that midazolam reduced mean corticosterone concentration by 29% and median lactate concentration by 30.3% at the mean arrival time (42 min post‐dosing) relative to the control group. These effects had abated by the mean induction time (99 min post‐dosing). Unexpectedly, blood pH was reduced in the midazolam treatment relative to controls at both arrival and induction, which likely resulted from sedative‐induced respiratory depression that was easily treated with intubation and mechanical ventilation, and administration of the reversal drug, flumazenil. Low blood pH was not associated with negative post‐surgical outcomes, as had been found in spectacled eiders with acidosis caused by anaerobic metabolism typical of physical exertion. Intramuscular injection of midazolam in the field effectively reduced stress and physical exertion in spectacled eiders prior to surgical implantation of transmitters. © 2021 The Wildlife Society.

Citation Information

Publication Year 2021
Title Effects of midazolam on corticosterone and blood gases in spectacled eiders prior to transmitter implantation
DOI 10.1002/jwmg.22046
Authors Maria Spriggs, Daniel Rizzolo, Kate Martin, Gwen E. Myers, Matthew G. Sexson
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Wildlife Management
Series Number
Index ID 70219486
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center Biology WTEB

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