A non-trauma-focused equine-assisted intervention was associated with reductions in all four PTSD symptom clusters in treatment-resistant military veterans.

Introduction: Veterans are at greater risk of developing post-traumatic stress disorder (PTSD) and show a poorer response to first-line treatments than civilians. Although equine-assisted interventions (EAIs) represent a promising alternative for military veterans,the underlying mechanisms remain uncertain, and their effectiveness across different PTSD symptom clusters has yet to be established. This study examined the effects of a non-trauma-focused EAI on specific PTSD symptoms in treatment-resistant military veterans. Material and methods: Participants in the intervention were military veterans diagnosed with PTSD by their psychological or psychiatric referrer, all of whom had received previous first-line trauma treatment prior to study enrolment. The dataset included 43 veterans who completed the Dutch PTSD Checklist (PCL) for the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) at week 1 and week 24, and who met the PTSD criteria at baseline according to the PCL-5. The EAI was a 12-week group program during which veterans had individual interactions with a horse once a week from 10:00 to 15:00. PTSD symptoms were assessed using the PCL-5 at weeks 1, 4, 8, 12, 24, and 52. Results: A linear mixed model showed that scores for all four PTSD symptom clusters significantly improved over the course of the program. Cluster B (intrusion) and cluster C (avoidance) decreased even further after termination of the program at week 12, demonstrating additional long-term effects. Cluster D (negative changes in cognition and mood) and Cluster E (arousal and reactivity) remained low but did not decrease further after week 12. In addition, the reliable change index (RCI) and clinically significant change (CSC) were calculated, resulting in suboptimal (51.2%; Discussion: This indicates that 25.6% achieved both reliable and clinically meaning full symptom reduction in response to the program, and 23.3% demonstrated statistically reliable but not fully clinically significant improvement, while 51.2% did not show any improvement. Although responsiveness over time differed, all PTSD symptom clusters improved significantly during the EAI program in treatment-resistant military veterans. Suggesting that further research with controlled study designs on the effectiveness of EAI as an adjunctive intervention to TFT for military veterans with residuals symptoms would be of value.