I have a 3 year old boxer and a 5 year old Brittany who have grown up together and have been the best of buds until about 2 weeks ago..the boxer suddenly viciously attacked the Brittany. The boxer has always been the dominate one and the Brittany has never had a problem with it so that is why we are so puzzled as to what to do, since the Brittany already submits to the boxer we aren't quite sure what we can do to remedy the situation. There have been 3 vicious attacks since the first one several weeks ago. Any ideas to help make peace?