Welfare and stress of horses used for Equine-assisted services: A systematic review

Interest in Equine assisted services (EAS) has grown over the past two decades, with research highlighting the benefits for participants in ridden, or mounted services. However, there is a notable lack of studies focusing on the welfare of the horses involved in these services. As research in this area continues to develop, a review is necessary to evaluate the quality of existing studies about the welfare of horses in the EAS industry. Systematic reviews provide a structured approach to organizing current literature and identifying gaps in the research. The goal of this systematic review is to summarize the existing literature on the stress and welfare of horses in EAS and pinpoint areas requiring further investigation. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, five databases were searched using terms relevant to EAS. Of the search result, 28 papers met the criteria for inclusion, requiring research to be published in English, in a peer-reviewed journal, studying EAS and its effects on equine welfare. Of the 28, 24 articles focused on quantitative data, including behavioral and physiological indicators of stress and welfare. The remaining 4 articles were survey and EAS module analysis, providing qualitative data about EAS horses. From the selected papers, we found the following trends related to EAS horse stress indicators. First, 20 (71.4 %) papers investigated physiological indicators, and 16 (57.1 %) investigated behavioral indicators. The sample size in 16 (57.1 %) articles was ten or fewer animals. The results in 17 (60.7 %) of the articles found that there was no significant difference in horses' stress or that no conclusions could be drawn regarding the horses' stress and welfare. A survey conducted by Rankins et al. (2021) revealed that the most common problems EAS centers face are behavioral and soundness issues leading to high horse turnover. Despite these findings, many studies found a lack of significant differences in their results, likely due to limitations in study design, highlighting significant gaps in the research. We also identified several inconsistent factors that are likely to affect and confound the results of EAS research. Therefore, given the limited knowledge about the welfare of horses working in EAS and the confounding factors that are likely to influence the results of studies, more robust research is needed to better understand the challenges of horses working in EAS and their welfare.