I recently decided to try some of the smartpak products...Breeze has a prior hock injury from when she was 2 (herd separation anxiety problems) and she tore her back legs up pretty bad...and during certain times of the year can be pretty stiff, also inherited stifle issues from her Mom, only locked up on her once in her life time (she will be 5 in Jan) but if there is something to help her I am all for it. I started her on the smartpak smart MSM, not really expensive, but worth a try. She's been on it about 2 and half weeks now and maybe its my imagination but she is riding with alot more pep in her step than in the past. She just seems more at ease...Decided after reading someones post on here about their horse being dancy when being groomed in the belly area that turned out to be digestive/upset stomach issues that maybe that was my geldings Cochises issue..hes my slowest eater too...put in on the smart digest ultra from smartpak and I am noticing a difference. He eats more quickly than before (isnt the last one done)and he isnt as antsy anymore about grooming around his belly and sides...so I guess from my perspective I think its helped. I put my boarder horse (hard to keep weight on TB) on their smartgain 4....it has made his coat like mink is all I can say about it, and he loves it.