Maureen,
I'm so sorry you and Jag are faced with this.
I can recommend acupuncture as something that did help give Luna very good pain relief for a day or two, and you may want to look into acupressure, too. I did some with her for her intestinal disease and it seemed to help. But most of all, I think the most satisying thing for both you and Jag (in addition to any other methods that help him) would be for him to have your hands, the ones that he knows so well and loves so much, be the ones to come down on the floor with him and give him gentle, soothing, full body massages as often as you have the time to do it. As you well know, dogs live in the here and now, and to have the touch of the one he is closest to, here and now, on his body - will be very meaningful, and in my experience beneficial as well.