Evaluating Stress in Riding Horses: Part One-Behavior Assessment and Serum Cortisol.

Stress can impact the health and well-being of animals negatively. Behavioral and physiological changes, particularly serum cortisol, offer objective and easy-to-use methods of evaluating stress in horses. However, limited studies support a positive relationship between changes in stress-related serum cortisol concentrations and stress-related behaviors in horses. This study assessed differences in stress-related behaviors and serum cortisol concentrations in horses used in a therapeutic riding program (TRH) or university riding program (UNI). Riders were grouped by disability type (TRH) or by experience level (UNI) to determine equine stress impacts. Two trained observers evaluated equine behavior during multiple riding lessons. Behaviors were scored live and via video to assess the accuracy of live scoring. Blood samples for serum cortisol concentrations were collected before, immediately after, and 30 minutes after riding lessons. Serum cortisol concentrations decreased from before to after a riding lesson (TRH, P ≤ .01; UNI, P = .0004) and increased over the course of the study (TRH ≤ 0.0002; UNI, P ≤ .0001). All serum cortisol concentrations remained within or below normal ranges. Overall behavior scores were relatively low in horses participating in both riding programs. Similar behavior scores were observed in horses ridden by novice and experienced riders (P ≥ .1662); however, behavior scores differed in TRH horses ridden by one group of disabled riders during a riding lesson (P ≤ .0431). A relationship between stress-related behavior and cortisol concentration changes was not shown clearly, but data suggest that horses were in a low-stress environment.