While pain in dogs can be treated with narcotics, it's not often that it's used for chronic pain situations outside an inpatient setting that can be closely monitored. I suspect part of the reason is diversion: too many people take the meds meant for their dogs.
There are several NSAIDS to try that are safe for dogs. Deramaxx is a cox-II inhibitor like human Celebrex that worked the best for my dogs with osteoarthritis and one with hip dysplasia. Rimadyl is cheaper and worked fine for early symptoms but once they reached 10 or 11 years of age it just wasn't as effective. Tramadol (Ultram) is a pseudo-narcotic that can be used for pain in dogs. It's mild enough that most vets don't have a problem dispensing it for home use. You won't know until you ask your vet.
Preparations like shark cartilage and cosaquin are best used as preventives for joint health rather than for the treatment of pain. If they aren't helping, save your money for the more effective meds available from your vet. I know how hard it is to see our dogs deal with the pain of aging. Still, they handle it far better than we humans do. I always admired my dogs for the way they carried on in the face of adversity and still enjoyed life. :-)
Seeana, it's so nice to see you back again. I hope you had a happy and peaceful Christmas (where it's summer there down-under!)
I wish you all the best for the New Year.
Unfortunately I have very limited knowledge of pain relief medications either for humans or dogs. But as far as I know, an anti-inflammatory NSAID drug would probably be a good choice, for your Shane. Medication that helps to relieve associated inflammation would probably be better than just relief of pain in itself.
The best idea would be to have a good talk to your vet about the options.
Just out of interest (and this is most likely not of any help to him) but it is just as possible to do successful joint-replacement surgery on dogs as it is on humans! It might be interesting to investigate this....