good dog food for bladder and kidney stones

Anyone have a dog who is prone to bladder or kidney stones? My friend has a beagle who is but they have her on science diet w/d which seems to be working but her allergies are horrible and the first two ingrediients are corn and chicken by product. Not the best for a dog with allergies. There are tons of good food out there but we were interested in knowing if anyone has had success keeping stones away with say a fish and sweet potato and/or barley. Any info appreciated. Don't know why vets reccommend science diet when the main ingredients are corn and by products and even corn husks!

Try reading the site linked below, it may help you. I found it by googling " 'kidney stones' dog food"
   

   
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thanks!