Vets recommend Cosequine. But its megga expensive and unless the insurance are paying, it can be a lot to find every few months. But, it does work - sometimes. Our Joe was kept sound for years off it. The insurance paid for the first year and then we took over, it was money well spent. It didn't really work for Storm though as I tried her on it too. You can buy it online a bit cheaper than from the vets though.