Effect of the observer’s gender bias monitoring acute pain using a validated behavior scale in castrated piglets

Abstract

Abstract We aimed to investigate the observer’s gender bias on acute pain assessment using the Unesp-Botucatu Pig Composite Acute Pain Scale (UPAPS) in piglets before and after castration. Twenty-nine piglets were filmed at 1h pre-castration, 0h and 3h post-castration. Two observers self-identified as women and two as men, and all four observers assessed all films using the UPAPS. Intraclass correlation coefficient (ICC), Lin's concordance correlation coefficient (CCC), and Bland-Altman were used to estimate the agreement, and modeling was conducted to compare genders. The ICC of the UPAPS total sum was ‘very good’ (0.84) when considering both genders and ‘good’ when considering each gender separately. Furthermore, women had a higher level of agreement (0.74) than men (0.65). The agreement of the UPAPS total sum assessed by women and men demonstrated minimal bias (-0.04), no proportion bias, and 55% of the assessments were identical. The UPAPS total sum was statistically equivalent between genders (P = 0.66). In conclusion, we found no evidence supporting gender bias in applying UPAPS in piglets before and after castration. Our findings permit the assessment of piglets' acute pain regardless of the observers’ gender, which might benefit the swine industry and researchers monitoring pain in piglets.