Started this based on study reported on Horse.com, about 2 months into last hock injections on one 20 yr. old. Decided a month later to give to 2nd 12 yr. old horse that was into 8th month since last injection. Now on 3rd jar of EquiThrive and both are still showing no signs of needing injections. Hope it continues that way. 4 star because product is so expensive. I have noticed that the key ingredient, resveratrol (though perhaps in a different form), is popping up in other supplements for both horses and people.