Concentración de cortisol como bioindicador de bienestar animal en la manada equina expuesta a estímulos sociales

Abstract

Equines are highly sensitive to stress, meaning that any activity around them can trigger a release of plasma cortisol, thus impacting their well-being. Research on this subject has primarily focused on the utilitarian aspect of these animals, which often involves exploiting them beyond their natural capacities and consequently compromising their health. This study aimed to determine serum cortisol levels using the quantitative ELISA (Accubind) technique in a herd of horses used for equine-assisted therapy, compared to a stable group at the same location, measured at different times of the day as a bioindicator of animal welfare. For this purpose, eight castrated male horses from the same herd were selected, with four participating in equine therapy (experimental group) and four not (control group). Blood samples were drawn twice daily over five different days, resulting in a total of 80 samples. The cortisol range in the experimental group was 10.97 ± 5.73 μg/dL, while in the control group, it was 9.03 ± 3.99 μg/dL (p≥0.05). A significant difference was found between groups when comparing the interaction of circadian rhythm (morning and afternoon) (p<0.05). Horses in the control (10.21 μg/dL) and therapy groups (11.94 μg/dL) began with similar values; however, the control group showed a decrease (7.84 μg/dL) in cortisol levels by the end of the day, unlike the therapy group (9.99 μg/dL). These results indicate that equine therapy affects cortisol levels, possibly due to the physical effort involved, which may disrupt the animals' circadian rhythm. Keywords: ELISA; Stabled; Equine-Assisted Therapy; Circadian Rhythm