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A non-trauma-focused equine-assisted intervention was associated with reductions in all four PTSD symptom clusters in treatment-resistant military veterans.
Abstract: 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. Unassigned: 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. Unassigned: 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%; = 22), improved (23.3%; = 10), and recovered (25.6%; = 11) treatment-outcome groups. Unassigned: 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.
Copyright © 2026 Kapteijn, Fennema, van Huffelen, Endenburg, Vermetten and Rodenburg.
Publication Date: 2026-06-03 PubMed ID: 42317715PubMed Central: PMC13273901DOI: 10.3389/fpsyg.2026.1787669Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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Overview
- This study explored the effectiveness of a 12-week, non-trauma-focused equine-assisted intervention (EAI) in reducing symptoms of post-traumatic stress disorder (PTSD) among treatment-resistant military veterans.
- The intervention led to significant improvements in all PTSD symptom clusters, with some effects sustained or enhanced even after the program ended.
Background and Purpose
- Military veterans are at a higher risk of developing PTSD compared to civilians and tend to respond less well to conventional first-line treatments.
- Equine-assisted interventions (EAIs), which involve therapeutic activities with horses, have shown promise as alternative treatments but lack clear understanding of their mechanisms and effectiveness across specific PTSD symptoms.
- This study aimed to evaluate how a non-trauma-focused group EAI affects the four symptom clusters of PTSD in veterans who did not respond to prior trauma treatments.
Participants and Methods
- The study involved 43 military veterans diagnosed with PTSD by mental health professionals; all had previously undergone at least one standard first-line trauma treatment.
- Participants completed the Dutch PTSD Checklist for DSM-5 (PCL-5) at multiple timepoints: weeks 1 (baseline), 4, 8, 12, 24, and 52.
- The 12-week EAI program was conducted in groups, with each veteran engaging in individual interactions with a horse once per week for 5 hours (10:00 to 15:00).
Assessment Tools
- The PCL-5 measures PTSD symptoms grouped into four clusters based on DSM-5 criteria:
- Cluster B: Intrusion symptoms (e.g., flashbacks, nightmares)
- Cluster C: Avoidance symptoms (e.g., avoiding reminders)
- Cluster D: Negative alterations in cognition and mood (e.g., negative beliefs, emotional numbness)
- Cluster E: Alterations in arousal and reactivity (e.g., hypervigilance, irritability)
- Reliable Change Index (RCI) and Clinically Significant Change (CSC) were calculated to categorize treatment outcomes:
- Recovered: Both reliable and clinically meaningful symptom reduction
- Improved: Statistically reliable improvement but not clinically significant
- Suboptimal: No significant improvement
Findings
- Statistical analysis using linear mixed models demonstrated significant reductions across all four PTSD symptom clusters during the 12-week intervention period.
- Notably, intrusion (Cluster B) and avoidance (Cluster C) symptoms continued to improve even after the program ended, indicating sustained or delayed long-term benefits.
- Negative cognition/mood (Cluster D) and arousal/reactivity (Cluster E) symptoms remained at reduced levels but did not show further decline post-intervention.
- Treatment outcome classification revealed:
- 25.6% of participants reached both reliable and clinically significant improvement (recovered).
- 23.3% showed reliable improvement but not sufficient for clinical recovery.
- 51.2% did not exhibit meaningful improvement in symptoms.
Interpretation and Implications
- The non-trauma-focused EAI program was associated with symptom reductions in military veterans previously resistant to standard PTSD treatments.
- Improvements in intrusion and avoidance symptoms suggest that interaction with horses might engage mechanisms that reduce traumatic recall and behavioral avoidance.
- The lack of further improvement in cognition/mood and arousal/reactivity after week 12 may indicate these symptoms require additional or different therapeutic approaches.
- Given that about half of the participants did not improve, EAI is not universally effective but shows promise as an adjunctive therapy.
- Authors recommend further controlled studies to:
- Validate EAI’s effectiveness as a complementary intervention alongside trauma-focused therapies.
- Explore mechanisms by which equine interactions contribute to symptom reduction.
- Identify which veterans are most likely to benefit from this approach.
Conclusion
- This study supports the potential of non-trauma-focused equine-assisted interventions to alleviate PTSD symptoms in military veterans who have not responded well to conventional treatments.
- The benefits appear particularly notable for intrusive memories and avoidance behaviors, with some sustained improvement beyond the active treatment period.
- Further rigorous research is warranted to optimize and integrate EAIs into PTSD treatment regimens for veterans.
Cite This Article
APA
Kapteijn CM, Fennema RA, van Huffelen R, Endenburg N, Vermetten E, Rodenburg TB.
(2026).
A non-trauma-focused equine-assisted intervention was associated with reductions in all four PTSD symptom clusters in treatment-resistant military veterans.
Front Psychol, 17, 1787669.
https://doi.org/10.3389/fpsyg.2026.1787669 Publication
Researcher Affiliations
- Animals in Science and Society, Department of Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
- GGz Centraal, Amersfoort, Netherlands.
- Mentrum Psychiatric Hospital, Amsterdam, Netherlands.
- Animals in Science and Society, Department of Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
- Department of Psychiatry, Leiden University Medical Centre, Leiden, Netherlands.
- Animals in Science and Society, Department of Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
Conflict of Interest Statement
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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