Here is the website of Dr. Kaen Tobais, the leading livershunt research veternarian. When I had a question about one of my kids, I sent her an email and she responded within 24 hours.
http://www.yorkielane.com/LiverShunt/
Liver shunt can be very difficult to diagnose -- many different illnesses share the same type symptoms. A full fasting blood profile will give your vet a starting point to decide on what other tests might be necessary.