Injectable Rx Adequan works
It is very expensive, but does help restore the synovial fluids and therefore lubricate the joints. Not a good idea to Bute regularly, hard on digestive system as mentioned. We found that putting the bute inside a hollowed-out banana worked like a charm, however. My boy is retired with a huge arthritic knee. So sad, he's only 20 but former owners overrode him. He went completely lame a few months after I got him. Adequan helped him to move better overall and I'm hoping that his knee hurts less too. Apple cider vinegar is supposed to help, 1/2 to 1 cup per day. I mix it with rolled oats and if you like you can add a little molasses. My horses really like the tart taste. Good luck, I understand that if you keep your horse active and don't overdo it you can continue to ride for awhile.