Purpose: Pet therapy is a non-pharmacological intervention, but its scientific value is still undefined.
Methods: The first step to identify the papers of interest was the access to the MEDLINE library from 1960 until June 2007 and the Cochrane controlled trials registry.
Results: At present there is consistent evidence of the protective effect against cardiovascular risk, mainly through the moderate exercise prompted by walking a dog. Indeed, walking a dog may contribute to a physically active lifestyle. Moreover, patients suffering from chronic illness are likely to benefit from pet companionship.
Conclusions: There is a contrast between physical effects (for which the evidence is fairly clear) and the psychological benefits (for which the evidence is controversial). Further randomised researches are necessary to convey scientific dignity to the human - animal relationship.