My 8-month old Retriever is a champion puller. I tried this harness after another dog owner told me she'd used it on her Lab and claimed that "it was like walking a totally new dog".It seemed to work for the first week or so (it wasn't "walking a totally new dog" though, he still tried pulling and was being a pain). After that, he must have figured out some way of getting around it, because he started pulling again. I checked to see if it had loosened, and it hadn't.When walking on a loose lead, this harness causes the leash to jump up and down violently, which gets very annoying for the walker.Lastly, one has basically zero control over the dog when using this harness. My dog managed to knock me over by cutting in front of me. If I had been using a collar, I could have prevented it.So, basically, I can't say I really recommend it. I'm not very satisfied with it and considering returning it.