Can anyone recommend a dog harness that does not slip to the side of the shoulder when walking the dog. I have a step into harness that no matter how tight or loose I make it, it seem to slip to either her right or left side of shoulder when walking. She is not a puller. I have been using a martingale collar for this reason. I have to use a martingale as her head is smaller than her neck and regular collar can slip off if she gets frightened by another dog charging at her. She will not run away but stays by my side, but I would feel safer knowing she can not slip out.