I have one of those for my big dogs(2 german sheperds and 1 doberman), I think they should only be used if the person knows how to use them. You could seriously hurt the dog if you pull to hard. I was taught how to use it in my agility class with Maggie.
My dogs are very good with the collar, one pull(not rough) makes them stop and they will enjoy the rest of the walk calmly.