Relationship between hair cortisol concentrations and equine personality assessment

Understanding a horse's personality may allow for improved management of the animal. The equine personality assessment (EPT) includes 4 main personality factors: anxiety, trainability, affability, and gate entrance. This tool uses a 1 to 9 scale. For 6 questions, 1 indicates a horse presenting the opposite of a trait (e.g., calm), 5 is neutral, and 9 indicates a trait is fully present (e.g., nervous). The other 13 questions determine the frequency of a trait's presence, with 1 indicating rarely and 9 indicating often. Many personality assessments characterize horse stress. Cortisol concentration, a quantitative measure of stress, is deposited throughout an equine body and is detectable in almost all tissues. Hair cortisol concentration (HCC) allows a long-term assessment of average cortisol. As personality is an ongoing characteristic, analyzing HCC provides a comparison between the 2 tools. The objective of this study was to evaluate potential relationships between EPT results and HCC. It was hypothesized that the personality trait of anxiety would directly correlate to HCC and that personality factors of trainability and affability would be inversely related. Seven workers at the university's Equine Center responded to a modified EPT, which analyzed 32 university horses for 3 personality factors: anxiety, trainability, and affability. Workers evaluated horses with which they had had 2 or more interactions lasting at least 5 min. Interactions ranged from general handling to riding but needed to be one-on-one. Based on this, not every student evaluated every horse. Equine tail hair (1.0 g) was collected in the 2024 Spring and Fall semesters. Samples were split into 0.5 g subsamples and extracted based on previously published methods. Analysis was performed using SAS's General Linear Model and Mixed Model, evaluating the effect of personality traits on HCC. Mean worker assessment scores for anxiety, trainability, and affability scores were 4.49 ± 0.91, 6.19 ± 1.20, and 6.13 ± 1.00, respectively. Log-transformed overall mean HCC was 2.71 ± 0.21 pg/mg. There were no significant differences between personality traits and HCC (P ≥ 0.50). These findings suggest that HCC is not associated with personality traits using the EPT. This study only evaluated one of many equine personality assessment tools, and results should not be extrapolated to other instruments as this may not accurately represent potential personality assessments-HCC relationships.