Intentional dog poisoning

Dog poisoning happens in my city a lot. People just don't poison dogs free on people's yards; they go on popular walking roads and drop some pieces of poisonous meat (or other treats) along the road and just wait until the dogs come out with their owners, watching the dogs to eat the pieces. It's awful and many people have put up Facebook pages to alert people if they see suspicious behavior on some roads, so people wouldn't walk their dogs in those areas. I don't really get it why would some people use their free-time, and money, to do such things to precious little pets!