A 2009 review of Reaching the Animal Mind by Karen Pryor, the trainer who popularized the term and practice of clicker training over three decades
Always try positive reinforcement before resorting to any form of punishment—it produces fewer unwanted side effects—but certain dogs just won't learn to avoid temptation with tricks and treats alone
My dog, Brutus, loves his toys to the point where he attacks other dogs that try to play with them. And it’s not just his toys. Say we’re at the dog park and there is a dog that is playing with a tennis ball: He will steal the tennis ball from the other dog and get very mean if that dog tries to take it back or even share it. At home, I have to take his toys away and put him in time out, which is him being sent to his crate.