I've been using products from the link below for about 3 years now with zero issues. I have 4 large athletic working dogs, which is why I make sure they're receiving their supplements along with a raw diet. This company makes a powder formula which is easy to mix in with raw or kibble, and it's much easier to feed than pills and gel tablets, etc where you end up trying to trick your dog to eat it. These dogs are smart, and are able to easily get around the "trick" to NOT eat the pill. Haha! Hope this helps. Good luck with your pup!
The Wholistic Pet
Oh, and we've used the Wholistic Canine Complete, the Joint Mobility, and the Run Free. You can read and compare the products, and also contact the company with your situation and they will email you back with their suggestions for your particular problem.