Sorry to hear about your dog. How was your dog diagnosed? Is your dog showing any symptoms? Did you have a specialist read your X-rays or were they only read by your vet? If you take the X-rays to a specialist, you can get a definitive opinion of exactly how bad they are.
Depending on symptoms, you have a variety of drug options. In my opinion, glucosamine is great. If you try it and your dog is still in pain, you can go to adequan injections. They are relatively inexpensive and you can give your dog the injections yourself to save money. I pay $200 for 8 injections (2/week). You can give the injections 2 times per year.
I would definitely get some ideas from your vet on pain management. The next thing to know is how advanced the arthritis is in the joints. Then you want to see how much muscle loss your dog has.
There is a lot you can do for your dog. Remember to get regular exercize to help keep him moving.