[Help] How can I train my miniature pinscher to stay in the backyard without a leash?

My minpin is almost 2 years old, so it may be too late, but I thought I'd give it a shot.He is wild, and I really do not trust him outside without a leash, but it would be amazing if I could play with him out there, and he would enjoy it as well.What can I do to train him to do this at this age? Is it possible? via /r/dogs http://ift.tt/2snm0Y6