Doesn't seem to be doing much.
I have two cats, both 3, one with pre-existing dental problems. I've been consistently buying this product for a year and the cat with pre-existing tartar problems, still has them, but I was expecting it. What I wasn't expecting is that my other cat (not related to the first one) also now has gingivitis, while she NEVER had teeth problems before. So it didn't help the cat who needed help with dental products and didn't prevent the cat who had perfect teeth from getting dental problems.