I really don't know how the glucosamine works on dogs but I do know my vet told me it was a waste of money for horses and she never did recommend it for the dogs. My son's dog has a very bad back, he's paralyzing slowly and the hind really gives sometimes. The vet gives him one shot a month for the pain, been over a yr now and the dog is doing great. I can't remember the name for sure, it might be the Convenia...whatever it is I'm amazed at how it totally took the pain away , the dog can actually move without whimpering. He will still end up paralyzed but this seems to have halted the whole process.