I used it on my QH gelding when he was going through a hock fusion several years ago. Lately, he's been showing "hock issues" again (I think the other side is going now). I did a course of Adequan, which was marvelous, but he wasn't quite up to going a month apart for the maintenance. I started him back on Duralactin, and I'm sure it is helping.
I tried it on my other horse, who has been diagnosed with navicular issues, and it didn't seem to help him much. So, I think results can be somewhat individual.
"One person's cowboy is another person's blooming idiot" -- katarine