The antifreeze solution is far from non violent.It would be a slow agonizing death.A couple of years ago my cousins two Rottweilers got into a drain pan full of the stuff.Anti freeze has a very sweet taste.It was not a pretty sight.Ultimately they were taken to the vet and put down,there was nothing they could do for them.
Perhaps you have a neighbor who you're not really fond of? Trap the critter and deliver him there in the dark of night.
