Stress responses in horses used in Hippotherapy

Abstract

Hippotherapy is increasingly used to address physical, occupational, speech, and psychological disabilities of clients, but research in this area is limited. The available research concludes that Hippotherapy provides many benefits to the client. Because Hippotherapy utilizes horses as part of the treatment team, it is vital to understand physiological wellness, potential sources of stress, and stress mechanisms in the therapy horse during the therapeutic process. Currently, there is some debate whether horses used for therapy are stressed in therapy situations. The North American Riding for the Handicapped Association (NARHA) recommends that therapy horses complete no more than three-consecutive sessions per day. The objective of this study was to measure potential stress mechanisms in the therapy horse during three-hour consecutive hippotherapy sessions. Five Quarter Horses from the Texas Tech University Therapeutic Riding Center completed two treatments, a control where measurements were taken at rest from 1200 h to 1700 h, and during Hippotherapy where measurements included pre-session (1200 h to 1300 h), three consecutive Hippotherapy sessions (1300 h to1600 h) and post-session (1600 h to1700 h) measurements. Heart rate was measured every three minutes, and blood samples were collected at the beginning of each hour to assess neutrophil counts, lymphocyte counts, neutrophil:lymphocyte ratios, monocyte counts, basophil counts, eosinophil counts, and cortisol levels. The behavior of each horse was assessed by a modified behavior scale by a NARHA instructor who was blinded to the study results. It was concluded that there was a horse difference for cortisol secretion. Horse by treatment interaction was significant for cortisol, heart rate, lymphocyte count, neutrophil-lymphocyte ratio, monocyte count, and basophil count. Treatment by time interaction was significant for heart rate. Two of the horses may have been stressed due to higher cortisol and lymphocyte levels. One of these horses scored poorly o the behavior scale and was removed from the program due to increased agitation. However, the other horses were ideal based on desired behavioral traits. Both stress physiological measurements and the behavioral survey may allow therapeutic riding centers to better assess potential therapy horses and determine if current horses are being worked the appropriate amount or if adjustments need to be made.