I have mine on Topspec 10:10 joint supplement as it was recommended by my horse McTimoney guy. My horse wasn't actually showing signs of stiffness though but we have put him on it as he's 18 and we still compete so more of a preventative measure I guess.
Still, he does seem to be quite perky and bouncey now - whether that is down to the supplement I don't know. i am thinking of giving it to my older pony as he is a little stiff so maybe that'll show if it does actually work.
i would reccommend Stride or STride HA, its great and really shows a difference. bit more expensive than most joint supplemtns but by far the best i have used. bought some online lately and it was a good price
I would always recomenf grand meadows look at the article on their site called the truth about joint supplements it is a good read. www.grandmeadows.com
I give cortaflex, was a bit concerned because it contained ingredients derived from marine origin but the results are fantastic and keep my 21 yr old mare extremely spritely, I buy the 3.6kg tub for £175 which lasts 512 days