Development of a composite index framework for comprehensive assessment of chemical immobilization performance in tigers (Panthera tigris).

INTRODUCTION

Chemical immobilization is an important part of veterinary care in tigers (Panthera tigris) as it allows animals to be safely handled for routine health examinations, diagnostic procedures and treatment.

METHODS

This study evaluated the clinical performance of a medetomidine (0.04 mg/kg)-ketamine (3 mg/kg) protocol in 40 facility-managed tigers (22 males and 18 females) undergoing routine disease screening and surveillance as part of the Annual Health Checkup. Induction, physiological responses, need for supplemental medication and recovery were assessed using the Immobilization Scoring Index (ISI), Induction Predictability Index (IPI), Protocol Reliability Index (PRI), and Recovery Grading System (RGS). The ISI had a maximum score of 16 and classified immobilization as excellent (13-16), good (9-12), moderate (5-8), or poor (≤4). The IPI was used to assess the consistency of induction, while the PRI indicated how often satisfactory immobilization was achieved with the initial drug dose. Recovery was graded as Grade I (smooth), Grade II (mild ataxia), Grade III (excitable/hyperkinetic), or Grade IV (severe dysphoria). Rectal temperature, respiratory rate, heart rate, capillary refill time, mucous membrane color, and peripheral oxygen saturation were monitored every 10 min during immobilization.

RESULTS

Vital parameters remained within clinically acceptable ranges, and no major anesthetic complications were recorded. Satisfactory immobilization was achieved with the initial dose in 87.5% of tigers, while 12.5% required additional ketamine. The mean ISI score was 13.9 ± 1.1, indicating excellent overall immobilization. The IPI was 5.26%, indicating relatively low variability in induction time within the study population, while the PRI was 87.5%, indicating that most tigers achieved adequate immobilization without supplemental ketamine. Most tigers (92.5%) recovered with Grade I or II responses, indicating smooth to mildly ataxic recovery.

DISCUSSION: Overall, the medetomidine-ketamine protocol provided reliable and clinically satisfactory immobilization in these facility-managed tigers. The proposed scoring systems helped describe different aspects of immobilization in a simple and structured manner. However, further studies are needed to validate these measures before they can be recommended for wider use across different anesthetic protocols or felid species.