When I was with a dog therapy group visiting hospitals and assisted living, facilities, we would
all met outside first, in a spot to let the dogs relieve themselves before taking them into the facility. Also, this was a good time to allow rookie dogs to get acquainted with the more experienced dogs. Our mentors told us to always let the dogs check each others licence plates. She said that is how they identify each other. I thought that was a cute way of saying it.