you are describing my first dog that i had when i was about 7 or 8 and he died when i was sixteen. He looked like a collie crossed with a mongrel. He would only of weighed 35lb but he loved killing things.Mostly cats but his real passion was fighting other dogs which he did whenever he could,no matter what size or shape he would attack without warning.I did a lot of obedience with him and my biggest achievment with him was getting him to stand from the stay position (lying down) from a distance.Thats not easy. I could never break him from fighting or worrying sheep though despite giving him s