I tried compounded acetyl-d glucosamine a few years back on my then 19 yr old horse with little effect. I ended up doing Adequan which did help him a lot. If you are treating a specific problem, you may want to give Pent Aussie a try as that is injectable glucosamine with pentosan (an anti inflammatory similar to Adequan). Otherwise, for maintenance, I think oral supplements do a fine job as long as it’s a good quality supplement like the Smartflex line, Cosequin, Recovery EQ, etc. I am not totally convinced any supplement or injectable can really *prevent* arthritis though. It’s so hit or miss- one bad step in the pasture can put the horse out to pasture!