Again, my heartfelt thanks for all your kind notes and comments.
I hadn't posted anything previously. I kept this one to myself until I had more information.
The Specialist, at this point, doesn't feel the kidney stone will move. I hope he's right.
MrD - several years ago, Pucci had serious problems with bladder stones, the worst type a pet can have, Calcium Oxylate. He had major bladder surgery and a number of procedures to flush stones out of his urethra. He would not have been able to undergo further such procedures. He's been on appropriate medication ever since. We now added kidney medication to what he's already taking.
As an FYI to other pet owners, I used to give Pucci his medications in peanut butter at the end of my finger. When he developed bladder stones, I researched oxylates and found that peanut butter is EXTREMELY HIGH in oxylate content. I stopped giving him peanut butter immediately.
I'm concentrating on what the Specialist said - for an almost 11 year old living in the desert, he's doing very well.