Facial hair whorl location, behavior, and ocular temperature as a physiological stress indicator in young Pura Raza Española dressage horses

Most horses presented a single FHW, predominantly along the eye line (60.2%). Behaviorally, a balanced profile was common, with strong correlations observed between aggression and dominance (<i>r</i> = 0.75, <i>p</i> < 0.001), and learning and cooperation (<i>r</i> = 0.72, <i>p</i> < 0.001). Eye temperature increased significantly just after competition, with higher values in horses with FHW along the eye line (<i>p</i> = 0.019). The number and location of FHW were associated with some interactions between nervousness, dominance, and/or aggression (<i>p</i> < 0.05). Multivariate analyses identified three distinct clusters, with the most favorable group characterized by FHW below the eye line, lower post-test temperatures, and high learning and cooperation scores. These findings demonstrate that, although FHW alone are not sufficient to predict temperament or stress reactivity, their integration with behavioral and physiological measures allows the empirical identification of distinct functional profiles in PRE horses.