I have 2 female Maltese x Shih Tzu's, 4 yrs old, Abby & Layla. They are from the same litter so have always lived together and normally get along great! However, recently while walking them, if they see another dog they get really excited wanting to meet, sometimes crying and barking to get to the other dog, then Abby bites Layla on the face/ear (not hard enough to draw blood or for Layla to cry). I'm assuming that Abby is doing it as a dominance thing? Its really embarrassing. Any ideas on how to stop this?