Development of a zoo anesthesia score for clinician-perceived risk of anesthesia-related mortality in zoo animals

Decision-making in zoological medicine is complicated by limited data and broad diversity of species, making standardized risk assessment and communication to non-veterinary stakeholders challenging. This zoo anesthesia score (ZAS) was developed using multi-criteria decision analysis (MCDA) to quantify clinician-perceived risk of anesthesia-related mortality, offering a more nuanced tool than general veterinary scales like the American Society of Anesthesiologists (ASA) status. A modified Delphi process with seven zoo clinicians identified key criteria thought to influence risk of anesthesia-related mortality: individual health status, previous examination history, taxon-specific risks, anesthetic protocol safety and efficacy data availability, clinician experience, induction method, and anesthetic monitoring. Subsequently, 66 zoo veterinarians participated in an MCDA survey to assign relative weights to these criteria. Individual health status, a criterion akin to ASA status, was overwhelmingly the most important factor (mean weight 33.7), followed by taxon-specific risks (15.5). Clinician experience and anesthetic data availability were moderately weighted, while procedural aspects, like induction method and anesthetic monitoring, received lower weights. The ZAS provides an additive scoring system (0–100), with higher scores representing increased perceived-risk, that integrates individual patient, species-specific, and institutional factors. This tool was designed to facilitate shared decision-making (e.g., is the procedure worth performing?), highlight modifiable risk factors (e.g., what can make the procedure safer?), and enhance patient safety by offering a structured approach to assessing anesthetic risk in diverse zoological collections. Future validation studies would determine if ZAS offers improvement over ASA for discriminating between those patients that do and do not actually experience anesthesia-related mortality.