Behavioral and physiological responses of horses to ground-based adaptive horsemanship lessons for veterans with post-traumatic stress disorder (PTSD).

Overview

• This study investigated how horses respond behaviorally and physiologically to ground-based adaptive horsemanship lessons involving veterans with PTSD.
• The researchers compared horses involved in these lessons to control horses to assess stress levels through hormone measurements, muscle activity, and observed behaviors.

Background and Purpose

• Adaptive horsemanship (AH) is used as an equine-assisted service to support veterans with PTSD, but little research has focused on how horses themselves respond to these interactions.
• The study aimed to evaluate horses’ welfare by measuring stress-related physiological and behavioral responses during ground-based AH lessons.
• Understanding horses’ responses is important to ensure their well-being during therapeutic programs.

Study Design

• Participants: 12 gelding horses divided into two groups:
  • AH group (6 horses, average age ~20.3 years) engaged in ground-based adaptive horsemanship sessions with veterans diagnosed with PTSD.
  • Control group (6 horses, average age ~13.8 years) stayed in their stalls located in an arena and served as a baseline comparison.
• Duration: 8-week sessions were conducted.
• Data Collection:
  • Blood samples taken at multiple time points during the lesson (start, 3, 5, 25, and 30 minutes) to measure plasma levels of cortisol, epinephrine, norepinephrine, and oxytocin using validated assays.
  • Surface electromyography (sEMG) was used to monitor muscle activity in masseter and brachiocephalic muscles continuously.
  • Video recordings captured horse behaviors for later analysis.
  • Three trained observers assessed stress-related behaviors using an ethogram to count the number and duration of such behaviors.
  • Qualitative behavior analysis was performed by 22 observers who described horses’ temperaments.

Measurements and Analysis

• Physiological Data:
  • Hormone concentrations: cortisol (stress hormone), epinephrine and norepinephrine (fight or flight related), and oxytocin (related to social bonding and stress reduction).
  • Muscle activity: sEMG signals were processed to calculate average rectified values and median frequency to assess muscle tension or relaxation levels.
• Behavioral Data:
  • Measured the frequency, types, and duration of stress-related behaviors as a quantitative measure of horse stress.
  • Observers qualitatively rated horses for anxiety, nervousness, stress, calmness, comfort, patience, and relaxation.
• Statistical analyses involved repeated measures ANOVA to consider differences between groups over time, with significance set at P ≤ 0.05.

Key Findings

• Hormones:
  • Control horses showed significant increases in cortisol levels late in the sessions (at 25 and 30 minutes), indicating elevated stress.
  • AH horses did not exhibit this stress-related cortisol increase, suggesting better stress management or habituation.
• Behavior:
  • AH horses displayed fewer total and unique stress-related behaviors compared to control horses.
  • Observers qualitatively described AH horses as being calm, comfortable, patient, and relaxed.
  • Conversely, control horses were described as anxious, nervous, and stressed.
• Physiological muscle activity data were collected but specific results were not highlighted in the abstract, suggesting no major issues or differences.
• These combined physiological and behavioral outcomes indicate that horses involved in ground-based adaptive horsemanship lessons with veterans showing PTSD are less stressed than those just confined in stalls.

Implications and Conclusions

• The results support the idea that horses engaged in ground-based adaptive horsemanship with veterans experience less stress and maintain better welfare compared to horses kept in more restrictive stall conditions.
• This suggests that regular interaction and an active role in therapy sessions may provide mental or physical stimulation that reduces stress responses in horses.
• The study provides valuable evidence for equine welfare considerations in adaptive horsemanship programs, emphasizing that horses can be partners in therapeutic settings without compromising their well-being.
• Further research could explore long-term effects, specific muscle activity patterns, and refine protocols for optimizing horse welfare in equine-assisted services.