Stress cortisol and muscle stiffness in horses used for equine-assisted therapy

Abstract

Equine-assisted therapy uses horseback riding to improve the patient's health and wellbeing. However, the possible stress and damage of this therapy on the back horse muscle (longissimus dorsi) are understudied. We studied the stress cortisol and muscle stiffness of two ponies and a horse used for equine-assisted therapy on a child with autism. Salivary cortisol levels and heart rate were used as indicators of physiologic stress and a muscle indenter was employed to estimate the back muscle stiffness. Saliva samples were collected before and after equine-assisted therapy and then were analyzed by direct enzyme immunoassay technique. Heart rate was measured by a Heart Rate Monitor at rest, during therapy at 5 minutes intervals for 30 minutes, and after therapy at 5 minutes intervals for 20 minutes. The muscle stiffness and muscle tone along both sides of the segments T14, T16, T18, and L2 of the longissimus dorsi muscle were obtained before and after equine-assisted therapy. Both salivary cortisol and heart rate did not have significant differences as a consequence of the therapy. Similarly, although a horse tended to have more muscle stiffness after the treatment, overall the therapy had little effect or none on the horseback. The equine-assisted therapy does not seem to create a negative impact on horses. However, further studies with a greater sample size in children and horses should be carried out to confirm whether equine-assisted therapy is completely safe for horses' health.