In my brother and my early teens to late teens, we had a medium size collie. I bet she didn't weigh 60 lbs. She didn't bother any of the other animals unless a cat would get too close to her food dish while she was eating. It would happen so fast that you couldn't stop her. She would be eating. Grab the cat behind the head, shake it twice, drop it and go back to eating. Cat was dead in a second. When we would drag small square hay bales with bale hooks out in the pasture for the cows in the winter, her job was to keep the cows out in the pasture from getting out the gate. She was very good at it. Only once did a cow get the best of her by kicking her as she was chasing it back through the gate. She yelp and went down hard. My first thought was that probably ruined her because she got up and ran away from the cow horribly scared. Both me and Pat started hollering at her to sic the cow. We both took off running at the cow. The dog went from fear to a rage in an instant. She went after the cow biting her in the back legs and belly. That had to hurt cause the cow was bellering while the dog chased her all over the pasture. We finally had to call her off. After that, none of the cows would even try getting out the gate when the dog was there. She was one of my favorite dogs except for one little thing. Dad named her Lassie. All's I heard when the cousins/friends would come over was, " Oh no Lassie, did Timmy fall in the well again? We better go find and save him. Unfortunately for them, she liked the game of sic em. Timmy would always get the last laugh.