Dogs adapt without training to anti-pull harnesses, but you'll have to take some time to teach your dog to wear a Gentle Leader. Before using the Gentle Leader during walks, it should be introduced to the dog in a systematic way so its less aversive than just slapping one on the dog. Here is a sample process for teaching your dog to wear a Gentle Leader. Do not progress to the next step in the process until you have achieved the goal on the current step. You can expect to spend a couple of days completing all the steps.

1 Show the dog the Gentle Leader and then give him a generous handful of tasty treats – repeat this several times per day until he is demonstrating a happy, anticipatory response when he sees the Gentle Leader, very much like the response dogs have when they see their leash come out of the closet.

2 Play a targeting game with the Gentle Leader where you hold out the Gentle Leader and reward the dog every time he bumps it with his nose. A clicker trained dog is a plus here to mark nice responses.

3 When the dog is targeting as quickly as you can present the Gentle Leader, reward only after every two or three nose bumps. While doing so, try to select the nose bumps that are a little longer and stronger.

4 Hold the Gentle Leader with the entrance to the nose tube facing the dog. Reward him for getting his nose anywhere in that area now. Give especially large rewards when he does any approximation of putting his nose right in. It’s okay to prompt responses at this stage by holding a treat at the other end so that the dog must insert his nose in order to collect through the tube. It is sometimes okay to leap right in with this prompting exercise, skipping parts 1 -- 3, but the most prudent course of action is to spend a bit of time with the preliminary exercises.

5 The reward standard is now the dog putting his nose right into the Gentle Leader. If you have achieved this with luring, fade this lure now so that the dog must put his nose in before you produce the treat rather than putting his nose in once the treat is visible at the end.

6 Add duration to step 5. Once the dog’s nose is in the Gentle Leader, delay giving the reward through the hole for a second or two. Praise him lavishly while he waits. Tell him how attractive he looks. Gradually increase the time he must remain in to 10 seconds.

7 Adjust the Gentle Leader straps so that they would fit him extremely loosely. While he is waiting in the Gentle Leader for his treat, as per step 6, start fiddling with the head straps while he waits. When he is used to this, try snapping the Gentle Leader on very loosely. Praise him for all you’re worth the first time you attach it and feed him generously. When you first start messing with the straps, he may withdraw his nose for a while – if he does, back off temporarily and then try again with more subtle strap-fiddling.

8 Adjust the straps so that they are closer to a correct fit (which is snugly around the back of his head, right up under the occiput, the pointy bone at the back of his head). Snap the Gentle Leader on and give him extra praise and food rewards again. He is so handsome!