I recently had a foster dog with severe arthritis. After a few days on Metacam there was a huge improvement in his mobility.
Recently I read an article in the Whole Dog Journal about a more natural remedy called Dog Gone Pain. The article is available online but you will probably have to pay for it if you are not a subscriber. The author raved about the results with her dog.
Here is the web site :
http://www.doggonepain.com/