update on my four-legged friend:
Talked to the vet. The type of stone removed was calcium oxalate, which was my worst fear. Medically a mystery, prone to recur (even with careful diet) and no way to dissolve them with diet if they begin to recur.
It is recommended he has a urinalysis and raidograph every 3 months for awhile, and then every 6 months... probably forever to ensure if they do recur, it can be caught before surgery is necessary.
So, I have decided the pup has to go back. I talked to the rescue society today, and they are very understanding. We both made an error in judgment proceeding before all the facts were in. The rep I have been working with mentioned another little guy, same age, housebroken (was given up rather than rescued) that I may be interested in. I've got mixed feelings:
1) I don't really deserve a dog, feeling like a hypocrite being ready to take on responsibility, but un-willing in this situation considering I only have had the dog a few days (This could happen to any dog. I feel like the situation would be different if he had been a pet for awhile, but it shouldn't be.)
2) The little guy broke my heart, and I'm just not interested in looking around right now. (you'd think I just went through a bad breakup, right?)
So, it looks like after work today I'll be re-entering the pet-less population.