Wondering what joint supplements you give, which ones actually work (I've heard of a few studies that claim glucosamine and such are basically just placebos). Jackson will be 5 next week, and is in good shape. I've never really seen any signs of joint troubles, but he is an active dude, and we're back in agility once a week. Should I be giving him some type of supplement just to be precautious? If so, what would you recommend? I'd probably prefer a powder or a chewable, that I can mix in with food, vs. a pill (he's annoying to pill).