If a choke chain is used improperly you can severly damage your dogs threachia internally.

Puppies should ALWAYS be trained in a flat nylon collar.

Riot was first trained to heel in a flat collar - then as his conformation training progressed he was switched over to a thin show choker.

He ONLY uses his show choker when he is in the show ring, or praticing for the show.

Any other time he is with a flat collar.
If your dog pulls, I suggest getting either professional help or using a haltie. They are fabulous and do wonders. In Riots RallyO class there is a BC there that was a horrible little puller. Now she heels without a leash thanks to her halti training.