Investigating the influence of animal-assisted services and service dogs on moral injury in military veterans: A scoping review

Abstract Background : Moral injury (MI) is increasingly recognized as a distinct consequence of military-related trauma involving moral, emotional, and social disruptions that differ from the fear-based symptoms characteristic of post-traumatic stress disorder (PTSD). Animal-assisted services (AAS) and psychiatric service dogs (PSD) have demonstrated psychological and social benefits for veterans with PTSD, but their relevance to MI has not been systematically examined. This scoping review examined how AAS and PSD may influence MI-related outcomes among military veterans. Methods : A scoping review was conducted using Arksey and O’Malley’s five-stage framework and reported in accordance with PRISMA-ScR guidelines. Searches were performed on August 7, 2025, across nine databases without publication-year restrictions. Eligible studies included peer-reviewed research involving military veterans or service members with PTSD who participated in AAS or were partnered with a PSD. Given the novel focus on MI, studies of other structured programs involving intentional therapeutic engagement with animals were also retained. Studies were included if they directly assessed MI or examined outcomes conceptually aligned with Litz and Walker’s social-functional model. Results : Eighteen studies met the inclusion criteria from an initial pool of 266 records. Only one study directly assessed moral injury using a validated measure. Across equine-assisted services (EAS), PSD, and nature-based programs (NBP), findings mapped to all six domains of Litz and Walker’s social-functional model, with the strongest evidence for social impacts, moral emotions and moods, and changes in beliefs about life meaning and purpose. More limited evidence was identified for alterations in moral thinking, perceptions of self and others, and self-harming and self-sabotaging behaviors. Although PTSD symptom reductions were consistently reported, these findings should not be interpreted as direct evidence of improvements in MI. Conclusions : The optimal treatment for veteran MI remains undetermined. Although direct evidence is limited, mapped findings suggest that EAS, PSD, and NBP may influence multiple social-functional domains of MI. These modalities may represent a more comprehensive complementary approach to military-related trauma than previously recognized by addressing moral, emotional, and social consequences beyond fear-based PTSD. Future research using validated MI measures is needed before firm conclusions can be drawn.