Background: Animal-assisted intervention plays an important role in improvement of mental health and elimination of sense of isolation.

Objectives: We conducted a meta-analysis of randomised-controlled trials to systematically evaluate the efficacy of AAI for mental disorders.

Methods: Relevant articles published were identified in PubMed, Embase, the Cochrane Library, Web of Science and Chinese Biomedical Literature Database. Study characteristics, population characteristics, animal-assisted intervention, measurement instruments of outcome were extracted. The evaluated outcomes included quality of daily life, behavioural and psychological symptoms, and mental condition. The effect sizes were calculated that the change in mean outcome from pre-test to post-test in the intervention group minus that same change in control group. All statistical analyses were performed with STATA version 12.0 software.

Results: 18 studies were identified. According to meta-analysis, we found that AAI have a
significant effect on the quality of daily life with psychiatric disorders (SMD 1.42, 95%
CI 0.05 to 2.78), and on the behavioural and psychological symptoms with depressive disorders (SMD 3.79, 95%CI 1.90, 5.68). We identified a difference between 2 to 3 monthes after AAI for quality of daily life with mental disorders (SMD 0.79. 95%CI 0.28, 1.30).

Conclusions: The present meta-analysis suggests that AAI can improve quality of daily life
with psychiatric disorders, and behavioural and psychological symptoms with depressive
disorders.