Canidae platinum dog food has all kinds of vitamins in it for arthritis and joints and glucosamine, and it's all-natural with no corn, soy, wheat, colorings, artificial flavors, or preservatives. It's one of the best dog foods you can find. I wouldn't really worry about putting your dog on drugs and stuff until you really notice the dog getting a little lame or stiff, just because it's not nessecary. Just give that food a look. There aren't any good-quality commercial dog foods out there.

Good Luck!