The article compiles extensive research on animal fear, personality, and behavior, with a particular focus on horses. It reviews various fear assessment methods across species, highlighting the stability of fearfulness as a temperament trait in horses and its influence on performance. The studies emphasize the importance of understanding equine personality, including breed, use, and husbandry factors, to improve welfare and training outcomes. Additionally, the article discusses the prevalence and causes of horse-related injuries, underscoring the need for better safety and educational efforts.

Further, the article explores the anatomical and functional bases of equine facial expressions and their relationship with emotions, using tools like the Equine Facial Action Coding System (EquiFACS) and the Horse Grimace Scale (HGS) for pain and emotional state assessment. It also addresses behavioral laterality, facial hair whorls, and their correlations with temperament and motor laterality. Advances in technology, such as machine learning, are noted for their potential in modeling fearfulness and recognizing facial expressions of pain and frustration in horses, contributing to more objective and nuanced welfare assessments.