Dog-Assisted Therapy as a Complementary Intervention in the Therapeutic Process of Adolescents in a Mental Health Day Hospital: A Randomized Controlled Mixed-Methods Study

Background Adolescents receiving intensive treatment in mental health day hospitals often present severe emotional dysregulation and low therapeutic engagement. Dog-assisted therapy has been proposed as a complementary intervention; however, evidence in structured clinical settings remains limited. Methods A mixed-methods study was conducted at an adolescent mental health day hospital. The quantitative phase consisted of a randomized controlled trial including 70 adolescents aged 12–18 years, allocated to Dog-assisted therapy or treatment as usual. The intervention comprised eight structured Dog-assisted therapy sessions. The primary outcome was global clinical functioning (HoNOSCA), while secondary outcomes included anxiety, emotion regulation, depressive symptoms, and eating disorder symptomatology. Immediate emotional changes were assessed before and after each session using the Facial Image Scale. The qualitative phase involved in-depth interviews analyzed using a hermeneutic phenomenological approach. Results No statistically significant between-group differences were observed in primary or secondary outcomes following the intervention. However, Dog-assisted therapy participation was associated with significant and consistent reductions in immediate emotional distress across sessions (Facial Imagine Scale; p < 0.001). Qualitative findings indicated that Dog-assisted therapy facilitated emotional regulation, improved mood, and enhanced therapeutic engagement and interpersonal communication. Conclusions Dog-assisted therapy does not appear to modify global psychopathology in short-term day hospital interventions; however, it was associated with consistent improvements in immediate emotional regulation and therapeutic engagement. These findings support its role as a process-oriented complementary intervention in intensive adolescent psychiatric care