Do potent immobilising-opioids induce different physiological effects in impala and blesbok?

Area of Science:

• Veterinary Medicine
• Wildlife Biology
• Pharmacology

Background:

• Potent opioids can negatively impact immobilized antelope physiology.
• Species-specific differences in these opioid effects are not well-studied.

Purpose of the Study:

• To compare the time to recumbence and physiological effects of opioid immobilization in impala (Aepyceros melampus) and blesbok (Damaliscus pygargus phillipsi).

Main Methods:

• A randomized two-way cross-over study involving eight animals of each species.
• Animals were immobilized using etorphine and thiafentanil (0.09 mg/kg each).
• Physiological variables (recumbence time, heart rate, respiratory rate, blood pressure, blood gases, lactate, glucose) were measured and analyzed using a linear mixed model.

Main Results:

• Thiafentanil resulted in a shorter recumbence time in impala compared to etorphine.
• Immobilized blesbok exhibited lower heart rates than resting rates, while impala heart rates remained within physiological limits.
• Impala showed severe respiratory compromise and hypoxemia, whereas blesbok experienced only moderate compromise.

Conclusions:

• Significant species-specific physiological responses to potent opioid drugs exist between blesbok and impala.
• These clinically relevant differences highlight that extrapolating immobilizing drug effects between African ungulate species is not advisable.