Please have your vet contact Dr. Sharon Center. I posted her contact information for you in my post #4. She is one of, if not the, leading authorities on liver disease in the country. She developed the bile acid test. We have had numerous members on the Maltese forum I belong to contact her for advice on how to proceed after high BAT results.
Dr. Center has applied to the AKC for a grant to look for genetic markers for liver shunts in certain breeds, including Yorkies. She has also spoken to the World Congress on the subject.
http://www.vin.com/proceedings/Proce...2675&O=Generic
Dr. Center recommends that a Protein C test be done after two high BAT's. Please don't waste your time and money on any other tests until you get a Protein C test.