University of Tennessee has one of the highest success rates with liver shunt surgeries, especially on the really little ones. They do surgeries on extremely tiny yorkies all the time. If I were you and had to get surgery, this is the place where I would go. Dr. Tobias is wonderful.
Ammonium urate stones ARE symptoms of liver shunt and liver problems. So, this actually is a symptom. What food is your baby on? How old is he? Have you joined the liver shunt/mvd group?
There's a test that can be done that is non-invasive that will help better determine if your furbaby has hepatic microvascular dysplasia or liver shunt.
It's called the Protein C test, and your vet would do bloodwork that they would send to Cornell...The information is in the FILES section of the liver shunt/mvd group.
They are a wealth of information over there on that group regarding liver disease. Please consider joining.
http://pets.groups.yahoo.com/group/L...d_MVD_Support/