Portosystemic Shunts FAQ
From that link:
What are the clinical signs of a liver shunt?
Clinical signs are often seen at a young age and include small stature, poor muscle development, behavioral abnormalities (circling, disorientation, unresponsiveness, staring into space, head pressing), seizures, and quiet demeanor. Other less common signs include drinking or urinating too much, apparent blindness, diarrhea, and
vomiting. In some animals the signs are associated with eating protein. Other animals are diagnosied when they take a long time recovering from anesthestics (i.e. barbiturates) or sedatives (i.e. acepromazine).
Some animals show no signs until they are older, when they develop bladder and kidney infections and stones.