Litespeed

I have seen a man and his wife on their hybrid bikes going up and down our street with their dog in tow. Our street is 1/3 mile long and is fairly flat. This is a black medium small sized dog that they have on what I call a yo yo string lease. I have seen them running the dog in 85+ weather up and down the street several times. The dog gets further and further behind each time they turn around and go back down the street. My husband and I were walking down our street one time and finally my husband told the guy "your going to kill that dog". The man's reply was "he loves it". His wife said "we are trying to wear him out". Finally they stopped and the dog laid on a lawn panting extremely heavily. We haven't seen them do it since, but if we do, I'm tempted to find out where they live and call the humane society. I feel like telling the guy, why don't you let your wife make you run up and down the street several times and see how you like it. Should I just mind my own business???