My Border Collie is a fat lazy 10 year old that came along with my wife. In her younger days she herded cattle on a big ranch in the high desert on the Oregon Nevada line. She worked the big circles. She is reasonably well trained. She will flat eat a cow but only on command. I learned early on not to say "get" because that is the magic word. Be closing a gate and casually tell a tame cow to get out of the way and the previously fat lazy dog turns into a black streak headed after that cow.
I took her with me to the cow sale last week. No leash needed, I tell her to stay with me and she is right there. We were waiting for them to start. We were sitting in the third row up. They ran a small steer into the ring. She snapped right to attention. Her ears were quivering. There was a guy standing BSing down in front of us. Every time that calf ran by so that guy was blocking her view she would lean to the right or left so she could keep that calf in sight. I am certain if I had muttered the word get, she would have cleared two rows of seat, climbed through the ring fence and got after that calf. And she is a fat lazy 10 year old.