I wanted to stop by your thread again after doing some updated reading on shunts. I am not sure if you are aware that the non-surgical dietary management of a PSS shunt is not good...
"About 50% of dogs with congenital PSS will live long
lives if they are medically managed appropriately and
they don’t get other illnesses. These are usually the dogs
that are less severely affected based on their clinical signs
and blood work. The outcome is much better for dogs
with extrahepatic congenital PSS that undergo surgical
closure with an ameroid constrictor or cellophane
band."
You may wish to read the article that I took the above quote from which was written by Dr. Tobias at UT. I posted it in another forum, but thought of your posts and wanted to come back and post it to make sure you saw it.
https://vetmed.tennessee.edu/vmc/Dow...NAL-201304.pdf