Lou Maria E, Porter Samantha T, Massey Jason S, Ventura Beth, Deen John, Li Yuzhi
Department of Animal Science, University of Minnesota, St. Paul, MN 55108, USA.
West Central Research and Outreach Center, University of Minnesota, Morris, MN 56267, USA.
Animals (Basel). 2022 Jul 30;12(15):1944. doi: 10.3390/ani12151944.
Proper methods of assessment to objectively identify pain are essential for welfare improvements of piglets undergoing surgical castration on commercial farms. The Piglet Grimace Scale (PGS) is used to identify changes in facial expressions caused by acute pain in piglets undergoing tail docking and castration. However, subjective scoring methods are a concern for the validation of the PGS. The objectives of this study were to evaluate and refine the PGS through 3D landmark geometric morphometrics. Male piglets (n = 88) were randomly allocated to one of two treatments: castration and sham-castration. Piglet facial images were taken at four time points (before treatment, immediately post-treatment, 1 h post-treatment, and 4 h post-treatment) using a photogrammetry rig. Images were scored by four raters using five facial action units (FAUs): orbital tightening, ear position, temporal tension, lip contraction, and nose bulge/cheek tension. Three-dimensional facial models were generated and landmarked denoting 3 FAUs (orbital tightening, lip contraction, and nose bulge/cheek tension). Results suggest that orbital tightening and ear position may be reliable FAUs for the PGS. However, neither the PGS nor 3D landmark-based geometric morphometrics were able (both p > 0.10) to reliably identify facial indicators of pain in piglets undergoing castration.
采用适当的评估方法来客观识别疼痛，对于改善商业农场中接受手术阉割仔猪的福利至关重要。仔猪痛苦量表（PGS）用于识别接受断尾和阉割的仔猪因急性疼痛引起的面部表情变化。然而，主观评分方法是PGS验证的一个问题。本研究的目的是通过三维地标几何形态测量学来评估和完善PGS。将雄性仔猪（n = 88）随机分配到两种处理之一：阉割和假阉割。使用摄影测量设备在四个时间点（处理前、处理后立即、处理后1小时和处理后4小时）拍摄仔猪面部图像。由四名评分者使用五个面部动作单元（FAU）进行评分：眼眶收紧、耳朵位置、颞部紧张、嘴唇收缩和鼻子隆起/脸颊紧张。生成三维面部模型并标记表示3个FAU（眼眶收紧、嘴唇收缩和鼻子隆起/脸颊紧张）。结果表明，眼眶收紧和耳朵位置可能是PGS可靠的FAU。然而，PGS和基于三维地标的几何形态测量学都无法（p均>0.10）可靠地识别接受阉割仔猪的疼痛面部指标。
