Ok, so let's look at the Gentle Leader. This device is often used by people trying to teach their dogs to walk beside them. Honestly, I don't think this device is necessary to use while training your dog.
Usually it is used by people who are so busy trying to get to the destination, they are forgetting about the journey. Here's the thing. Big or Small, you can teach your dog to walk beside you. You don't need a fancy head collar.
I know a lot of people talk about how they have to use it for the big dogs because the dog is "SO" much stronger than they are. Uh ... hello? I'm a pretty small person and I have trained some pretty big, pully, scary dogs. When the dog out-weighs you, you need to figure out a better way to train them that DOESN'T involve physical "persuasion".
The thing is that you spend time teaching them how to walk properly on a leash so that by the time you are ready to walk further, then they know what they are doing. You don't need to take your dog to the park in the first two weeks you own it! You don't need to walk it a million miles in the first month if you are spending lots of time (like 15 - 30 minutes every hour you are home) training him or her. Why? Because if you are spending that much time actively training, then your dog won't be bored, will he?
Did you know that I watch a total of 3 hours of TV per week? I have two shows that I watch (after dark) and THAT'S IT! The rest of the time I am outside with my dogs, working around the farm, training the other animals, or spending quality time with my hubby. If you keep your dog stimulated and teach him that he wants to be with you, then why would he ever try to run away when you're walking him?
One of my mantras that I use regularly is - A Tired Dog is a Good Dog. Well did you know that mental fatigue is more tiring than physical fatigue??
Here's an article about the "Not So Gentle Leader"
Here's a bit about Gentle Leader causing sores on the nose and hair loss
A few more on Sores and Hair Loss caused by the Gentle Leader
There are many other articles, stories, and instances of people whose dogs end up with sores on their faces after using the Gentle Leader. The sores can occur for a few reasons but the most common is that the device is not properly fitted to the dog. Sometimes people buy one for their 6 month old pup and the dog grows ... the device stays the same.
When I worked at the vet clinic there were many people who came in with dogs with nose sores from the Gentle Leader. Sometimes we could treat the wounds. Sometimes it was permanent. It was very sad when the owner of a 10 month large breed dog was told that their dog would probably have the bald spots for ever ... some would be grief stricken (not to mention guilt ridden!) ... others would opt to euthanize their dogs. All for the sake of a bit of training ...
Always remember - A Tired Dog is a Good Dog.
Have you used the Gentle Leader? What was your experience with it?