Physiologic Outcomes after Thiafentanil and Xylazine Immobilization in Free-Ranging Moose (Alces alces)

Lauren Ienello, Seth Moore, E. J. Isaac, Rachel Thompson, Alonso G.P. Guedes, Tiffany M. Wolf

Research output: Contribution to journalArticlepeer-review

Abstract

Effects on physiology were evaluated in 49 free-ranging moose (Alces alces), 11 adult males, 36 females, two of unknown sex) in Minnesota, USA, immobilized by helicopter darting with thiafentanil (10 mg) and xylazine (30 mg) in February 2020 and March 2021. Pursuit time (PT), induction time (IT), recumbency time (RT), recovery time (RC), temperature (T), and body position were recorded. For 14 females, respiratory rate (RR), pulse rate (PR), and pulse oximetry (SpO2) were obtained before and at 1, 5, and 10 min after 4 L/min nasal oxygen supplementation was started; pH, lactate (Lac), arterial oxygen (PaO2), and carbon dioxide (PaCO2) tensions were obtained pre-treatment and 5 min post-treatment. Immobilizations were reversed with naltrexone (200 mg) and tolazoline (800 mg) intramuscularly. Median PT and IT were 4 min; a longer dart needle significantly reduced IT (P¼0.0274). Most (98%) remained sternal; 77% held their head upright. Median RC was 3 min. Temperature remained ≤41.2 C. Median RR, PR, and SpO2 were RR¼20 breaths/min, PR¼70 beats/min, SpO2¼91% pre-treatment and RR¼30 breaths/min, PR¼72 beats/min, SpO2¼97% 5-min post-treatment. Median blood gas values were pH¼7.45, Lac¼5.62 mmol/L, PaCO2¼44 mmHg, and PaO2¼65 mmHg pre-treatment and pH¼7.48, Lac¼4.99 mmol/L, PaCO2¼41.1 mmHg, and PaO2¼78 mmHg 5-min post-treatment. Physiologic improvement from oxygen supplementation was clinically relevant but not statistically significant. All moose survived immobilization. Thiafentanil and xylazine combination provided safe and effective immobilization in free-ranging moose.

Original languageEnglish (US)
Pages (from-to)247-252
Number of pages6
JournalJournal of wildlife diseases
Volume61
Issue number1
DOIs
StatePublished - Jan 2025

Bibliographical note

Publisher Copyright:
© Wildlife Disease Association 2025.

Keywords

  • alpha-2 adrenergic agonist
  • capture
  • hypoxemia
  • oxygen supplementation
  • ultra-potent opioid

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