Research on dogs used for therapy in (Occupational Therapy)

Can someone point me in the direction for some research on pet dog assisted therapy? I don't mean the usual trained dog that visits people with learning disabilities, I mean using people with learning difficulties to train a dog and perhaps care for one. Very similar to what they do in America with prison cell dogs.
My partner is in the last year of her Occupational Therapy Degree and has chosen this form of therapy for her last assignment. She is finding it hard getting information.

Any help would be very much welcome.
Thanx.