Evaluation of medetomidine/ketamine for short-term immobilization of variable flying foxes (Pteropus hypomelanus)

Area of Science:

• Veterinary Medicine
• Wildlife Biology
• Pharmacology

Background:

• Variable flying foxes (Pteropus hypomelanus) require safe immobilization for research and sample collection.
• Assessing anesthetic protocols is crucial for minimizing stress and ensuring animal welfare in wildlife studies.

Purpose of the Study:

• To evaluate the efficacy of different medetomidine/ketamine (M/K) doses for short-term immobilization in adult male variable flying foxes.
• To determine the optimal M/K dosage for achieving a minimum of 30 minutes of relaxed immobilization.

Main Methods:

• Four intramuscular doses of M/K were tested: 30 mcg/kg/3 mg/kg, 40 mcg/kg/4 mg/kg, 50 mcg/kg/5 mg/kg, and 60 mcg/kg/6 mg/kg.
• Induction time, duration of immobilization, and physiological effects (bradypnea, bradycardia) were recorded.

Main Results:

• The highest M/K dose (60/6) resulted in the fastest induction time (31 +/- 46 sec).
• Higher M/K doses (50/5 and 60/6) provided significantly longer immobilization periods (52.5 +/- 25.7 min and 60.6 +/- 20.8 min) compared to lower doses.
• The estimated ED(50) for >30 min immobilization was approximately 40 mcg/kg/4 mg/kg.

Conclusions:

• A M/K dose of 50 mcg/kg/5 mg/kg is recommended for achieving over 30 minutes of relaxed immobilization in free-living variable flying foxes.
• This recommended dose ensures sufficient immobilization time for safe sample collection while considering physiological effects.
• M/K combinations offer a viable anesthetic option for field-based procedures on this species.