Be careful- If they are trained only on a gentle leader and then you want to do something where they can not use one, you might be in for a surprise. If you train them with one, be sure to spend the time to train them without one as well. What might happen is that when the gentle leader is on they are attentive, walk by your side, and are responsive to training. When the gentle leader is off they think that training time is done and will not be responsive, or listen, or do any training exercises. This is exactly what happened to me. I want to do agility with him but they do not allow the gentle leader in this class....without it he will not listen and it is like training him all over again from the beginning. He has been through 4 classes with the gentle leader on and listens perfectly when it is on. It is very hard. So, think first of what you want to do with your dogs and look at the gentle leader as a training tool only, because in some situations it might not be the answer you are looking for.