I dont know if I would do that, muzzles can inhibit their breathing and can make it impossible to pant and release their heat and he might over heat.. Unless you get one of those big muzzles that is open and they can open their mouths, but getting him used to that might freak him out.. I would get him a long line, they make 50-100' long lines. That way he is still leashed, BUT he can run around and walk farther ahead or whatever but he is still secured.