I have been using this on my large breed dog as well for a year and after the first few weeks of it, he showed improvement. After a few months, his limp was gone. When I ran out, he was limping again with pain. Now that he is back on it, the limping is gone again. It really has worked for him. I have his sister on it too as a preventative since they are both 8 years old as well. It works fast, it's the cheapest I have found, and they eat the tablets willingly (always a bonus).