Prong collars (also called 'pinch collars') are a series of chain links with blunted open ends turned towards the dog's neck. The design of the prong collar is such that it has a limited circumference unlike slip collars which do not have a limit on how far they can constrict on a dog's neck. The limited traction of the martingale chain combined with the angle of the prongs prevents the prongs moving close enough to pinch. The collar is designed to prevent the dog from pulling by applying pressure at each point against the dog's neck.
Herding breeds like border collies are the masters of this game, which is why you’ll see a ton of them at trials, but they’re not the only players. Chihuahuas, pit bulls, huskies, hounds, even Great Danes. You name it, my dogs and I have probably been shown up by it at some point. Surprisingly, certain toy breeds like Papillons have a real knack for agility.
Every dog needs to learn to walk on a leash. Besides the fact that most areas have leash laws, there will be times when keeping your dog on a leash is for his own safety. Learn how to introduce your dog or puppy to the leash, then teach him how to walk properly on the leash, even beside you on a bike. A loose leash walk teaches your dog not to pull or lunge when on the leash, making the experience more enjoyable for both you and your dog.