Sadly, if a liver shunt cannot be or are not repaired it does shorten a pup's life; BUT, that does not mean that is where your baby is right now!! Like the commercial on tv for the cancer center says: we are not born with expiration dates stamped on our feet....neither are our pups. I have seen extremely ill pups recover well...especially yorkies! They are a very resilient breed.
You didn't mention your vet. THAT is the first thing to do ... get him to a vet and get an exam and also blood work done. Perhaps there are other things going on that are an easy fix.
I am so sorry. It is so hard to watch a pup that you love so much be so sick. Just don't give up....get him to the vet to be sure what it is!
Please let us know when you go to the vet and how it goes. We do have people on this forum with liver shunt experience; but, most will tell you the same thing. Vet is always first! If he comes up as being really ill...you might also consider an internal med specialist. You can find one at :
American College of Veterinary Internal Medicine > Home