Here is what my friend had to say:
Sounds like struvite crystals which is No Big Deal. They are usually the result of a UTI, or if the person is feeding a very (weirdly) alkalizing diet. Typically once the UTI is treated, no more crystals.
They should quit the vegetables for a while, check for UTI and get a good quality kibble. I suggest Fromm. The dog should be a-okay. Also, IIRC, struvite stones can be dissolved once they get the dogs urine acidic again, so even if he has stones surgery probably isn’t needed. Plenty of water is always a good thing too. Add lots to his food.