I have an 18month old collie. When I walk him off lead he is fine until he sees another person or dog and gets distracted and runs up to them. To people he will jump up wanting to be smoothed, to other dogs will just sniff and run around.
However if there is no-one around and he wanders off and I call him, he will come back straight away. I have tried enticing him with treats but will not take anything when walking. I thought this might be that he doesnt like the treats but will eat them at home.