Are Equine Assisted Interactions (EAI) a Dark Horse Bet? A Systematic Review on Measuring the Psychological and Physiological Effects of EAI on PTSD, Anxiety and/or Mood Disorders

Background: Conventional forms of trauma-focused psychological interventions seem to be less effective in military veterans with post-traumatic stress disorder (PTSD). Equine Assisted Interventions (EAI) have become increasingly popular as an additional treatment, resulting in increasing research on the effects of EAI. However, no systematic review on the effects of EAI has focused on PTSD, anxiety and/or mood disorders and whether the effects are reflected in psychological and physiological measures. This systematic review investigated the treatment effects, study design, population, intervention, and psychological and physiological measurements in EAI research. Methods: The search strategy yielded 1028 original articles from 3 electronic databases: PubMed, Scopus, and CAB Abstracts. These articles were screened by 2 individual blinded researchers with Rayyan according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and rendered 31 eligible studies. Results: Although all quantitative studies reported 1 or more positive treatment effects on symptoms of PTSD, anxiety and/or mood disorders, well-designed studies were sparse. This review demonstrated a lack of methodological information and few randomized controlled studies, in addition to a large heterogeneity in population characteristics, interventions, terminology, and questionnaires. Conclusion: Future studies should address these methodological considerations in order to advance the understanding of EAI and optimize their efficacy in treating PTSD, anxiety and/or mood disorders.