Let me give you an instance of where a "vibrate" that can also shock, collar is necessary. We have Springer Spaniels and when they flush a bird in the yard or really anywhere, it's off to the races. For the first months after we get them, we walk with them and are with them almost every minute they are outside so they can learn how to behave. For the early part of those months, they wear a collar and if they start to go where they shouldn't, they get a "vibrate" which is enough to make them stop and adhere to their borders and our command.
Our command includes the word "STOP" or a whistle blown a certain way for an emergency situation. They learn in a few days and test it every now and then but after a couple months it's set in stone.
Last week while out, the one-year-old puppy took off in pursuit of a bird and was heading straight for a pond with maybe 1/4" of ice on it. She would have broken through and drowned while we watched from shore. No collar was on.
I yelled "STOP" and the dog hit the brakes and stopped just shy of the bank. Conditioned response of that training saved her life. There is no doubt that had she not been trained and learned the conditioned response drill that next was a vibrate on the collar that she did not like, and imminent. You could say that my training with that collar saved the dog's life.
You don't have to train this way and in a low risk environment it's easier to keep the dogs in check. For people with their dogs 24/7 and lesser risks, it can work. It almost works for us except when the dog can get in a situation bigger than they are. A combine too close or truck in the yard is outside their normal experience, and backup training is important to keep them from harm.
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