Aw poor guy! I don't know anything about Adequan, but my friend has a big akita with hip dysplasia and terrible arthritis. She takes him in to the vet regularily for chiro, and it helps ALOT. She says he feels SO much better after!
Do you have on of those canine hydrotherapy places in your area? One just opened up here. I've heard really good things about the hydrotherapy.