Evaluating hormonal levels in plasma and saliva as temperament indicators in horses

Assessing temperament is important to enhance welfare and safety in equine management. Biomarkers such as cortisol, oxytocin and serotonin have emerged as objective indicators of animal welfare because they reflect the physiological state of animals. This study investigated the correlation between the plasma and salivary concentrations of these biomarkers and their association with the observed temperament traits of horses, with the aim of developing a more reliable method for temperament assessment. This study involved 20 horses of various breeds and ages. Blood and saliva samples were collected for cortisol, oxytocin and serotonin concentration analysis using an enzyme-linked immunosorbent assay. Significant correlations were found between the plasma and saliva concentrations of cortisol and oxytocin, whereas serotonin levels exhibited no significant correlations. Cortisol levels in both the plasma and saliva were significantly correlated with temperament traits such as cooperativeness, gentleness and excitability. Oxytocin levels in both the plasma and saliva were correlated with friendliness. Plasma and saliva serotonin levels were correlated with trainability and concentration, respectively. This study highlights the potential use of saliva cortisol and oxytocin as markers for assessing specific horse temperaments. The results of this study suggest a direction for developing quantifiable methods for horse temperament assessment, which could improve horse management and welfare practices.