http://www.yorkietalk.com/forums/sic...ver-shunt.html
Here is a link to only one of the many threads about liver shunt.
Ultrasound unless done by a very experienced technician is not the diagnostic of choice to determine extrahepatic shunts. Scintography is.
Dr Tobias is a known expert in this field and the link to the thread I posted should have some details.
I'm so sorry that your baby had high bile acid levels.
It is recommended that pups are tested for BAT's prior to going home. Current thinking is that first BAT is done at 14wks and next one at 6months old.
Hopefully you do have a health guarantee that protects against genetic defects, which LS is.
It is highly advisable to go to the best specialists and surgeon you can find. If you are dealing with a general vet, you should ask for a referral to an internal medicine specialist, of if you can go to Dr Tobias go directly there.
Please keep us posted on how everything is and the very best for you and your pup!