Taken from Dog Channel
A dog pulls on the leash for several reasons:
• Sees, hears, or smells something exciting.
• Excess energy makes it hard for her to contain herself.
• Through experience, realizes that pulling on leash makes the handler walk faster or go the direction she wants.
• Because she can.
Why this dog behavior is a problem
Pulling on leash can start off innocently, but can become a problem for both the dog and the handler. The added pressure of the collar against the dog’s windpipe (trachea) can cause wheezing or coughing, which may be only temporary, or may cause long-term or even permanent damage to the dog. A dog who pulls strongly can cause the handler to lose balance and slip or fall. Strong leash pulling by a large dog, especially near roads with traffic, can lead to serious accidents.
Changing from a neck collar to either a head halter or front-attachment body harness can bring an immediate solution to leash pulling. These tools provide a mechanical advantage for the handler and do not cause pain for the dog. Using a head halter or front-attachment harness immediately allows the handler to control the direction and speed of the dog, without needing a lot of physical strength to accomplish this, but the dog still needs to learn how to walk politely, without pulling at all.
Teaching your dog to walk on a leash
A good way to teach loose-leash walking to a dog who pulls on the leash is to show her that pulling no longer “works” they way she thinks it will. When your dog starts to pull, simply stop walking. Stand still and wait for your dog to realize she’s not getting anywhere.
If your dog continues to pull after you’ve been stopped for three seconds, start very slowly walking backwards. Your dog will realize she’s losing ground now, not gaining it. When the dog turns around to look at you, wondering what’s gone wrong at your end of the leash, the leash will loosen a little bit. At that point, you can praise her and start walking forward again.
By consistently repeating this process each time she pulls, she will start to realize that pulling activates your “brakes” and not your “accelerator,” and the frequency of pulling will gradually diminish and eventually disappear.
Once your dog understands how to walk without pulling when wearing a head collar or body harness, you’ll be able to re-introduce her to walking politely while wearing an ordinary collar.