Comparison of cardiopulmonary effects of etorphine and thiafentanil administered as sole agents for immobilization of impala (Aepyceros melampus)

Silke Pfitzer; Leith Meyer; Liesel Laubscher; Kristin Warren; Rebecca Vaughan-Higgins; Jacobus P Raath; Michael Laurence

doi:10.1016/j.vaa.2020.06.007

Comparison of cardiopulmonary effects of etorphine and thiafentanil administered as sole agents for immobilization of impala (Aepyceros melampus)

Vet Anaesth Analg. 2021 Jan;48(1):53-64. doi: 10.1016/j.vaa.2020.06.007. Epub 2020 Oct 3.

Authors

Silke Pfitzer¹, Leith Meyer², Liesel Laubscher³, Kristin Warren⁴, Rebecca Vaughan-Higgins⁴, Jacobus P Raath⁵, Michael Laurence⁴

Affiliations

¹ Murdoch University, School of Veterinary Medicine, Murdoch University, Perth, Australia. Electronic address: silke.pfitzer@icloud.com.
² Centre for Veterinary Wildlife Studies and Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
³ Wildlife Pharmaceuticals South Africa (Pty) Ltd., White River, South Africa; Department of Animal Science, University of Stellenbosch, Stellenbosch, South Africa.
⁴ Murdoch University, School of Veterinary Medicine, Murdoch University, Perth, Australia.
⁵ Wildlife Pharmaceuticals South Africa (Pty) Ltd., White River, South Africa.

PMID: 33309195
DOI: 10.1016/j.vaa.2020.06.007

Abstract

Objective: To compare the cardiopulmonary effects of the opioids etorphine and thiafentanil for immobilization of impala.

Study design: Two-way crossover, randomized study.

Animals: A group of eight adult female impala.

Methods: Impala were given two treatments: 0.09 mg kg^-1 etorphine or 0.09 mg kg^-1 thiafentanil via remote dart injection. Time to recumbency, quality of immobilization and recovery were assessed. Respiratory rate, heart rate (HR), mean arterial blood pressure (MAP) and arterial blood gases were measured. A linear mixed model was used to analyse the effects of treatments, treatments over time and interactions of treatment and time (p < 0.05).

Results: Time to recumbency was significantly faster with thiafentanil (2.0 ± 0.8 minutes) than with etorphine (3.9 ± 1.6 minutes; p = 0.007). Both treatments produced bradypnoea, which was more severe at 5 minutes with thiafentanil (7 ± 4 breaths minute^-1) than with etorphine (13 ± 12 breaths minute^-1; p = 0.004). HR increased with both treatments but significantly decreased over time when etorphine (132 ± 17 to 82 ± 11 beats minute^-1) was compared with thiafentanil (113 ± 22 to 107 ± 36 beats minute^-1; p < 0.001). Both treatments caused hypertension which was more profound with thiafentanil (mean overall MAP = 140 ± 14 mmHg; p < 0.001). Hypoxaemia occurred with both treatments but was greater with thiafentanil [PaO₂ 37 ± 13 mmHg (4.9 kPa)] than with etorphine [45 ± 16 mmHg (6.0 kPa)] 5 minutes after recumbency (p < 0.001). After 30 minutes, PaO₂ increased to 59 ± 10 mmHg (7.9 kPa) with both treatments (p < 0.001).

Conclusions and clinical relevance: The shorter time to recumbency with thiafentanil may allow easier and faster retrieval in the field. However, thiafentanil caused greater hypertension, and ventilatory effects during the first 10 minutes, after administration.

Keywords: etorphine; immobilization; impala; opioids; thiafentanil; wildlife.

MeSH terms

Analgesics, Opioid / pharmacology
Animals
Antelopes*
Etorphine* / pharmacology
Female
Fentanyl / analogs & derivatives
Fentanyl / pharmacology*
Immobilization / veterinary

Substances

A3080
Analgesics, Opioid
Etorphine
Fentanyl