Mini Schnauzer stones (again)

Question
My 8 year old (fixed) female schnauzer apparently has developed stones The vet assumes calcium stones based on urine anaysis. She had an xray yesterday based on calcium crystals in the test. She eats TERRIFIC food: oven roasted chicken, lean broiled meat, assorted veggies, wild brown rice and LOTS of exercise: filtered water. Only her treats are store bought The doctor is recommending HILLS, is this cast in stone: can we continue with this home made diet WITH supplements to keep stones away? What supplements would these be. She weighs 8.5 kilos, and is healthy otherwise. Active, inquisitive challenging fun. Walks 5 miles a day even with the stones. Thanks Ardis in Toronto

Answer
I agree with your vet.  I know of a large, professionally managed, highly successful, spare no expense program that feed Hills.  Do you have any real proof a home made diet is better than the Hills would be?  

Also see http://www.avma.org/press/releases/070404_homemade_diets.asp

In the big recalls last year, not a single one of the high volume dry chow of any of the common brands was recalled.