My dog is approximately large labrador size. He looks like a very heavy set, powerful Rhodesian ridgeback. He is a big daft softie. I have had him since he was 9 weeks old (he is now 5 years). Ever since he was a puppy, he has pulled. He regards a walk as a tug of war contest. He has been to a series of training classes;I have tried harnesses, Haltis, etc. Nothing worked. He just pulls all the harder. He understands exactly what I want him to do, but he is determined to do anything but.
As a last resort, I had no alternative but to use a full-blown choke chain. That has had no effect: he still pulls until he chokes. It does not appear to bother him in the slightest. When I take him for walks, I return with my hands in agony, from the tension he exerts on the lead. I have sought advice from vets, trainers - he is apparently completely untrainable.
I still love him to bits, though.