I have an aging border collie that started limping about a month ago. We took him into the vet and had an X-ray done, nothing that they could find other than minimal arthritis. The vet said it wouldn't help to give him a supplement because the damage was already done, but for $12 a bag it was worth a shot. I bought two 4 pound bags from my local tractor supply store and have been giving him 2 a day since we started. I have seen a 100% turn around and rarely see him limp anymore, if any at all. His muscles are starting to come back and overall he seems a lot happier. I am hooked and bought the smaller bones for my schnauzer too. He's only a puppy, but it's good to start now! They're both picky eaters and jump for joy when they hear the bag crinkle.