Efficacy of animal assisted therapy on people with mental disorders: an update on the evidence

INTRODUCTION: Animal assisted therapy (AAT) is a structured form of animal assisted intervention (AAI), which specifically adopts animals in healthcare services and education facilities, to achieve therapeutic goals. Although such interventions are widely used, nowadays, evidence supporting them is still largely lacking. A previously published review of the literature highlighted some promising effects of AAT on people presenting psychiatric disorders, though the quality of the studies included was generally low. In order to provide an update of recent evidence, the aim of this study was to systematically review randomized controlled trials (RCTs) published since 2000, involving people affected by mental disorders and receiving AAT. EVIDENCE ACQUISITION: The following databases were searched: CINHAL, EBSCO Psychology and Behavioural Science Collection, PubMed and Web of Science. 115 papers were obtained and screened: 28 were from CINHAL, PsycINFO and Psychology and Behavioural Science Collection altogether, 15 from PubMed and 72 from Web of Science. In addition to this, grey literature and references of already published reviews and meta-analyses on the topic were searched, resulting in the addition of 6 further articles. After screening, 10 RCTs were included in this review. EVIDENCE SYNTHESIS: Studies involving outpatients were more frequent than those involving inpatients; sample size was generally low. The majority of studies adopted scales routinely used in clinical trials, with a good level of validity and reliability. Five out of ten studies reported significant differences in the main outcomes favouring AAT. Most of the studies did not include any follow-up; yet, where prospective data were available, the benefits of AAT appeared long lasting. Drop-out rates were higher in studies involving outpatients. However, the only trial which enrolled both inpatients and outpatients showed a higher drop-out rate among the inpatients group, possibly due to their more severe psychopathology. CONCLUSIONS: Though a paucity of available studies partly limits our findings, AAT seems to improve empathy, socialization and communication, and to favour therapeutic alliance among patients who have difficulties with therapeutic programs adherence. AAT appears to be a feasible and well-received intervention, potentially with few or no side effects reported. However there is a need for further studies with larger sample sizes and high-quality research standards.