The Piute Ground squirrel (Urocitellus mollis) is similar to the CGS (Spermophilus beecheyi) and the 13 lined GS (Spermophilus tridecemlineatus) in taxonomy. I think when we chatted you said he won't eat timothy hay that is normally a Prairie Dog base diet and I believe the Piute is more of a seed eater. Contact Dr. Gena Seaburg
kato@spro.net or 425-870-1729 and ask her about the correct Piute diet to prevent MBD. She is THE go-to expert on Prairie Dog nutrition and consults with zoos, vets and PD owners around the world. I learned everything I know about Prairie Dogs from Gena and Lynda Watson. She would also know about Piute's. Ask your biologist friend if he/she knows Gena.
You don't feed him any dried corn, right? That will damage his gall bladder.