I'm sorry.
Those numbers are high but because ultrasounds are so hard to read, the interpreter could've been wrong and maybe it's MVD...
Dogs with extrahepatic shunts should all be considered for surgery.
They will usually live a longer life with it.
The only place that I would want touching my dog for this is University of Tennessee. It is worth at least talking to them, especially if your current vet doesn't do the surgery and just knows how to do a bile acid test...
That being said, if you still don't want the surgery (totally understandable), with numbers like that and a suspected shunt, I think Lacy needs to be on lactulose. It can only help.
Could you post the ingredients of the diet that you are feeding and the nutrient analysis?
Fish oil can also be good but not just any kind.