I am wanting to get my 8 year old son some sort of reins/harness to keep him close to me when out. He is 8 but about the size of a 6/7 year old . It is particularly a concern when we are in busy public places as he tends to run off. I have heard you can get waist type reins/harnesses? Ultimately I am looking at getting a therapy dog for him and they can attach to the child via a waist harness so I would like a similar restraint to get him used to the idea. Any suggestions on where I could get something suitable?