Evaluation of Pain-Related Facial Expressions and Behaviour to Refine Perioperative Care of Cynomolgus Macaques

Abstract

Research primates may experience pain due to veterinary or experimental procedures and effective perioperative care is essential from a welfare and scientific standpoint. The aim of this work was to (1) create and validate a macaque grimace scale, and (2) assess analgesic therapeutic efficacy during the night. Video recording of cynomolgus macaques (Macaca fascicularis) (n=43) pre- and post-surgery was conducted, 1940 images were scored by observers (n=12), and detailed day (111 h) and night (224 h) behaviours were assessed. A novel grimace tool was developed and results indicated overall good inter-rater reliability (ICCaverage meanSD: 0.670.28). Construct/criterion validity was established as grimace scores increased significantly up to 17 h post-op compared to baseline (p<0.001), and behavioural trends correlated with grimace scores (rho=0.22-0.35, p<0.001). General and pain-associated night time behaviours significantly differed from baseline (p<0.05), but not social behaviour. These findings are important to refine perioperative care of research primates.