He's now had a good wee, a poo and his breakfast which turned into lunch. Maybe he was just having a Sunday sleep in? He's now back in bed again with little energy, but at least he ate and wee-ed.
Thanks to
@Beanwood mentioning xanthine crystals, I dug a little deeper into Dr. Google last night. Based just on the images of xanthine stones available online, I'd say that's what was removed. Hopefully the lab results will come in tomorrow to confirm.
To answer Kate's question, the surgeon didn't say anything about an abnormally shaped bladder. However, one of the reasons my own vet said she doesn't agree with the leaving the enlarged opening in his urethra is that if his bladder has a certain shape, the new opening won't do anything to help the stones to escape.
Also looking into why xanthine stones form, I believe I have a good (yet upsetting) clue as to 'why so many?' and 'why now'. Back at the beginning of March, I ordered and started to use a probiotic called "PetPlus" made in the UK. The ingredients are all good stuff that I've used before with my dogs. Unfortunately, I did not check the ingredients with interactions with Allopurinol. The main ingredient in PetPlus is brewers yeast, which is very high in purine and a 'NO WAY' for dogs on Allopurinol. The feeding amount for PetPlus is quite small (one teaspoon per day) but this could have contributed to the rapid build up of stones. No proof (correlation vs causation and all that), but of course I've stopped feeding PetPlus immediately.
Honestly, what I don't know about allopurinol, purines and Leish could fill the universe. I have to do better.
