When our tri was about a year old he pulled on his walks like a maniac- Yes we went thru leash training which he was a model dog, but when you went on straight walks he would start his crap again, so then I would do the training on the walk, again acts perfect (starting, stopping, turning, at randon-correcting when he goes ahead or turning around going the other way). So acts perfec tly on the training manuevers, but on walk mode he goes back to pulling. He knows training mode & he figured out regular walk mode.
Anyway we got sick of it and bought on of those collors with the spikes inside of it (a obediance class recomended trying it).
I put on the collar, he took off, I gave the leash a quick correction and he was startled and stopped dead in his tracks. He turned around shocked and looked up to me in the eye with a really hurt and pitiful look like "why are you doing this to me?"
I felt terrible I felt like I beat him or something. I took him home and put his regular cloth choke collar on.
We now have an agreement worked out between us. I allow him to stop & sniff, without yanking his leash and he does not pull on the leash on me (loose leash).
It's funny because when he has to go poop he pulls on the leash to the side because he has to go. So what he does is, he pulls me over, stops and looks up at me like saying "I have to go poop!" and I walk him back & forth till he goes.
My wife's sister took the dogs for a walk and had the tri. He kept stopping looking up at her all puzzled.
He's the only dog I ever met that actually looks up at people "in the eye" like he's trying to talk to you.