How to stop a dog pulling on the lead
Training Harnesses
A pulling dog can ruin a good walk yet it is a very common dog training problem. If you despair of your dog don't worry, you aren't alone and help is at hand. If you want to solve the problem there are several things you can try and each method has its merits. One way to show a dog how to walk properly on the lead is to use a dog training harness. They are ideal for dogs that won't wear a headcollar and they work by putting a gentle pressure across the chest which stops the dog pulling. 
I've been using this method of training for years by simply doubling a long lead around the dog's chest so as to use a gentle pressure if the dog pulls. In the photo on the left Jamie is walking on a loose lead doubled across his chest. I never thought of making a harness, otherwise I'd be rich and you wouldn't be reading this page. However, a number of other people have made harnesses especially for training the pulling dog. I've reviewed some of them below.
I've been using this method of training for years by simply doubling a long lead around the dog's chest so as to use a gentle pressure if the dog pulls. In the photo on the left Jamie is walking on a loose lead doubled across his chest. I never thought of making a harness, otherwise I'd be rich and you wouldn't be reading this page. However, a number of other people have made harnesses especially for training the pulling dog. I've reviewed some of them below. The Halti Harness
I bought this for my dog Jamie who is normally quite well behaved but if he does pull on the lead when I'm walking downhill I know it as he is quite big and strong. I found the Halti harness worked very well on him. Although he was still able to pull a bit it was nothing like the full blown, "I can tow you along," sort of pulling that he does if he sees a rabbit to chase. Jamie didn't like the restriction of the harness at first. mainly because he couldn't pull and he was frustrated, however, he soon got used to it. After a while I found that I needed the harness less and now I don't need to use it at all.
The Easy Walk Training harness
This is a harness that I bought for my dog Sasha as she's a champion puller. I bought it on the recommendation of someone who had a boxer and had found it was ideal for controlling this very strong dog. The Easy Walk does give more control than the Halti harness and it can be used for strong dogs. As with any harness, if you use it all the time do check that it isn't chafing. Sasha was just as dismayed as Jamie when she found that her pulling activities were being restricted. As with the Halti, she could still pull a bit but it was nothing like pulling on a lead and collar. The Lupi Harness
Here's another training harness that is very effective. It is easy to put on and it stops the dog pulling by using chest restraint. Do make sure though that the rope or cord type of harness such as the Lupi isn't too tight. It is designed to fit fairly loosely so that it doesn't cause any chafing on the skin.
More harnesses are available on the Dog's own ebay page All at excellent prices. A few examples are shown below.
Pet Planet also has other harnesses available and their prices are always very reasonable.