Help! My 2 dogs have recently become aggressive towards one another over food and bones. I have a 3 year old mixed breed that was adopted as a puppy, and a 1 year old stafforshire terrier mix that was adopted at around 4 months old. They have never fought before, but I have had to break up a couple NASTY fights over bones lately, and thave thus stopped giving bones. My 1 year old Rosie DESPERATELY needs to chew, and has become destructive with her chewing otherwise. THey are unsupervised in our backyard all day while at work, so I am now nervous to leave them alone with anything. ANY ADVICE????