This is interesting as Maddie is just over three and has started to do exactly the same thing apart from the recall which we always work hard on. It's very out of character for her in terms of the barking and growling at other dogs. I did wonder if she had picked it up from Bramble who has always been more reactive. At the moment I am using the clicker with her and watching her intently and surroundings to avoid any potential trouble, hoping it will pass. It will be interesting to hear other's views.