Tell your friend he should ask the surgeon who operated on the dog for a referral to a specialist. This dog will need to be monitored carefully at least for the first year for reoccurrence and to get the diet, medications, supplements just right.
If your friend prefers a more natural approach, consult a homeopath http://theavh.org/
http://vitalanimal.com/
Check out Wysong dog food, maybe someone at their 800 number could advise you
I don’t think the internet is a good place to get advice when you have something this serious, we can share our experiences….but that doesn’t mean that is what you should do, as far as I know there are no veterinarians or nutritionists here (none that have identified themselves as such anyway)
Best of luck
BTW: Dogs can have more than one 1 type of stones. Low protein diets can cause other types of stones to develop, that’s why you need the expertise of a specialist.
Add water to all meals, frequent bathroom breaks. For my dog 3-4 small meals per day instead of 2 regular seems to help too.
