Hello Fi What a lovely idea for your son. We have worked with autistic children and young people with learning difficulties for many years. The "key" is very often found through interaction with dogs and horses among other animals. We use registered P.A.T. dogs (one on site) and our own horses to build self esteem and confidence. Ringcraft, obedience, dog walking get togethers are all things your son could join in with. One of our young people, after two years of continuity and support, won not just his relevent age class ; but the whole national achievement award at CRUFTS 08. (Shaun Mc Alpine Award) Bryn will need a period of ajustment and understanding, but nothing is impossible. An older dog like Bryn would have the edge on a young dog coming into the household. Just dont disrupt his little routine or attention amount. We have a very old dog who as long as her "stuff" isnt messed with she accepts what ever passes through. As for breed P.A.T. dogs come in all shapes and sizes but have to be temperment tested. Ours is a poodle. We have used Brittany's Lab's collies and a Papillon. Rescues included. Good luck and very best wishes.