Abstract：
The use of grimace scales enables the clinical identification of changes in the facial expressions of animals caused by pain. The Horse Grimace Scale (HGS) is one such tool, comprising a pain coding system based on facial expressions and assessing six Facial Action Units (FAUs). Each FAU is accompanied by descriptions and anatomical details to assist the evaluator. However, the morphological descriptions for certain FAUs in the HGS are not sufficiently detailed, potentially hindering accurate interpretation. This study is an analytical investigation aimed at enhancing the morphoanatomical details in the HGS and providing raters with more comprehensive materials for pain evaluation in horses using this scale. To achieve this, detailed anatomical analyses were conducted using established references in veterinary anatomy. Initially, we propose substituting the term \'ear\' with \'auricle\' or \'pinna\' and replacing \'area above the eye\' with \'supraorbital region\' for anatomical accuracy. Additionally, we introduce detailed morphoanatomical descriptions that identify specific landmarks, with the goal of ensuring more consistent application of the HGS and reducing interpretation variability. Furthermore, this study provides an explanation of the muscles involved in the investigated FAUs. These adjustments on the descriptions and evaluations remain unverified, however it is anticipated that the descriptive enhancements lead us to understand that higher interobserver reliability can be achieved for each of the FAUs.
摘要：
使用鬼脸量表可以临床识别由疼痛引起的动物面部表情的变化。马甲量表（HGS）就是这样一种工具，包括基于面部表情的疼痛编码系统，并评估六个面部动作单元（FAU）。每个FAU都附有描述和解剖细节，以帮助评估者。然而,HGS中某些FAU的形态学描述不够详细，可能会阻碍准确的解释。这项研究是一项分析性调查，旨在增强HGS中的形态解剖学细节，并为评估者提供更全面的材料，以使用该量表进行马匹的疼痛评估。为了实现这一点，使用兽医解剖学中已建立的参考文献进行了详细的解剖学分析。最初，我们建议用“耳廓”或“耳廓”代替“耳朵”，并用“眶上区域”代替“眼睛上方区域”，以提高解剖学准确性。此外,我们介绍了详细的形态解剖描述，以识别特定的地标，目的是确保HGS的应用更加一致，并减少解释变异性。此外，这项研究提供了所调查的FAU所涉及的肌肉的解释.这些对描述和评价的调整仍未得到核实,然而，可以预期的是，描述性增强使我们理解，对于每个FAU，可以实现更高的观察者间可靠性。
