My 2yo girls do this on occasion, more than I would like. My original girl is insecure and the second one is bold (acting). When we got the second she was very aggressive and would attack my original pup (origi-pup). We of course put a stop to that. Now a year later they will both go at it. I think the origi-pup has had her fill of the other's bossy ways and now will strike, sometimes first. Of course we stop, put them both down on their backs until I see them relax. Not everyone agrees with this but it is what we do anyway.
__________________ "I do not at all understand the mystery of grace-only that it meets us where we are but does not leave us where it found us"-Anne Lamott |