Sorry to hear about your dog. I went through something similar a year ago with mine as well. I supplemented my dogs diet with a herbal product called Tripsy. It contains a powerful combination of herbal extracts proven to:
* Promote healthy kidney functioning
* Fight kidney infections
* Improve urinary flow
* Reduce the pain and discomfort of kidney stones
Tripsy is high effective, yet is totally natural and 100% safe for long-term use. I bought it online at Petwellbeing.
Possibly if you scroll down to Animal Health-General and click on it, you can ask a vet and he/she could give you some good answers.