One of my dogs has arthritis and has a difficult time getting around. I have researched various things from anti-inflammatory to natural remedies. The Veterinary Medical Journal suggest alot of the same medications that are given to people. I also consulted a vet on-line and they suggested the same. I give my Dalmatian/Border Collie hydrocodone-(Vicodin) on bad days and it helps him more than anything else. Of course, its only a temporary solution. I give him one when its time for him to exercise and strengthen his legs which is a big help.
However, certain breeds could have different reactions to certain meds so I would try to get as much information as possible before giving him anything. Alot of people over-react and run to the vet for everything. Remember, they are alot tougher than people give them credit for. If he's hurting, I would try to do whatever I could. Maybe an extremely small dose to see if any reaction occurs. I'm no expert, just not in a position to run to the vet. I would however, give him a nice little chat for not providing some sort of pain relief to begin with and I sure wouldn't pay for another visit to get them. Good luck and give him lots of TLC which helps them more than anything.