I had my aging cat on this for years. She had arthritis in her legs and I KNOW it worked because once, I ran out and she stiffened up immediately. As soon as I put her back on the product she was fine. They say this product is for dogs only but it is fine for cats too, they only had to make this labeling distinction recently, I don't remember why. Make sure you dont' give them a dog-size dosage though! just a little sprinkle a day.