We bought this to help control our dogs' barking at other dogs or people outside . . . but then we moved and left the dogs at the house with our grown son. We've used the trainer a few times, and our smallest dog (11 lbs), a pekingnese/rat terrier mix HATES it and will immediately run away and quiet down. The larger dog (22 lbs), a Boston/rat terrier mix, doesn't seem to be affected by it as much, altho it seems to work a bit if we stand directly in front of him.