Good read:
Hepatic Lipidosis in Toy Breed Dogs
This is going to be an interesting one because the shunting may have contributed to (or even caused) the hepatic lipidosis according to the above.
The treatment for fatty liver starts with a protein rich diet, but your doggie isn't allowed to have that, so...??? Hmmm. Maybe there is something better than the L/D or LS14 (or maybe not). Maybe you or you vet could email Dr. Center or somebody at UT to double check?
Yes, Denosyl for sure.
Are you doing any vitamins? Ursodiol?