I didn't get any pain or symptoms until the stone was on it's way from the kidney to the bladder. That stone is a stone in name only. When you see it it actually a little conglomeration of a million tiny needle points, and no two of them point in the same direction. So as it moves along the little tube it's in, it actually spears a million little holes in it. And this goes on for about two to four hours. And of course it's being pushed along by the liquid coming behind it.
I cannot imagine any food that could "break it up", as food doesn't come down that tube. I think it is mostly calcium, so certain acids will dissolve it. 'Course that same acid would dissolve everything else it comes into contact with, no lol.
I have no idea how dogs were created inside so, if the vet says it works I can't argue with that, and can only offer best wishes.
BTW; In humans,I've never heard of just one stone. If one makes a move, there's almost guaranteed to be some more waiting in line. Also not lol. I've passed two now, and there are at least 5 more waiting to mature.