I don't know if there's any benefit to giving it to a young dog as preventative, but last time I read about it, it was not recommended in humans for diabetics. You might want to do a little research on side effects.
I've taken it myself, and it did wonders for me. I had a hip shattered in a horseback riding accident in my 40's. The hip would get so stiff when I sat for any period, I'd be reluctant to get up knowing how it would feel. Within weeks that was gone. And then I was surprised when my knees, which I hadn't thought about in this regard, felt stronger (they'd both been hyper-extended, and I had to be very careful to keep them from doing it again). And then my back.... So it worked for me in a grand way, and it's noticeably helped a dog with arthritic elbows. However I've talked to people it did nothing for. I'm sure it doesn't help all dogs, and I think that's pretty much the case with most supplements of that sort. For instance the CBD oil some think is so wonderful has done nothing for either of my current dogs. It didn't affect the arthritis in my older girl and has no calming effect on the younger one.