While I can't recommend medication ,even though I did use aspirin on my dog with my vets advice for years,apparently that has changed. This was 20 yrs ago.
I did massage him twice daily and it really helped his discomfort.He would moan and stretch and he just appreciated it so much.I had a German Shepard with hip dysplasia.
Here is a link for massage.It will not get rid of the arthritis but it helps with the discomfort.
How to Massage an Arthritic Dog