Hi John, this could take quite a while to sort out because you don't know the precise reason she is doing this. It may well be a fear reaction to another person or dog but it might be some other trigger. It might even be you reacting in anticipation! HOwever, in your favour she is young and capable of learning. First step would be to get her to a vet that has someone (usually a nurse) who understands behavioural problems. It might even be worth a referral. The Adaptil collars are an excellent aid. By recreating the scent of the dam it can create a very reassuring environment, even on a walk. The real difficulty is to not imprint your reaction in case she reacts that then becomes her trigger to react!! Good luck