Good luck to Pouncer.

I'll tell you my story (trying to keep it short). Many years ago 1 cat (then a 2nd and then a 3rd) were found to be forming crystals (struvite). It wasn't until after 1 bladder stone removal operation, 1 catheter insertion for blockage and (luckily) the third was caught before this point, did the vet suggest ALL cats could be put on the c/d. That was 21 cats ago and only Rutherford formed the calcium oxilate stones. Was it due to the food? Perhaps. But the food has been a God-send to me and I will NEVER change unless a different prescription food is needed (as in Rutherford's case).