i have a two year old terv that goes to doggy day care with me. he has gotten into the habit of hearding some of the other dogs there. I would like to find a distance collar that will discourage this behavior. I have tried a citronella collar but he is no phased by this. I do not want to put a shock collar on him, he is very fearful and feel that this will not help the situation, or it will end up mentally harm him. Are there any other collar that work with the same concept (being able to trigger a "bad feeling" with a remote) other then these two devices.