Animal-assisted therapy in eating disorder treatment: A systematic review

Introduction: Eating disorders (EDs) are deadly illnesses with high relapse rates, highlighting need for better interventions. Animal-assisted therapy (AAT) has been implemented supplementally for EDs, with horses utilized at many residential facilities. AAT shows promise with meta-analyses of randomized control trials (RCTs) showing significant decreases in depression, anxiety, and negative affect; however, no review to date has evaluated efficacy for EDs. Therefore, this study conducted a systematic review of primary literature to investigate the efficacy of AAT for EDs. Method: A systematic review was conducted via PubMed, PsycInfo, and Google Scholar, up to and including September 2021, yielding 10 studies. Therapy animals included horses (n = 8), dogs (n = 1), and dolphins (n = 1). Populations included AAT ED therapists and patients (ages 11 to adult). The PRISMA methodology was used (registration PROSPERO CRD42021256239). Risk of bias assessment used Cochrane method for quantitative studies, Critical Appraisal Skills Programme checklist for qualitative studies, and JBI Critical Appraisal Checklist for Case Reports. Given study type heterogeneity, neither synthesis nor certainty assessments were conducted. Results: Case and qualitative studies reported improvement in cognitive flexibility, ability to relinquish control, and confidence. Quantitative studies demonstrated an inverse relationship between AAT utilization and ED symptoms post-treatment. Effect sizes, when reported, were mostly moderate. All but one study had low, or unclear, risk of bias. Limited randomization and a lack of RCTs measuring ED symptomology directly makes drawing conclusions difficult. Conclusion: While preliminary research indicates possible benefits of AAT as a complement to traditional ED treatment, more research is needed to establish efficacy. Future studies should employ randomized control trials and examine key mechanisms of change.