Hi, my dog Teddi had a liver shunt when she was 1 year old. We had surgery at University of Tennessee and she is now 3.5 years old and completely fine! I would suggest you join this goup:
Liver_Shunt_And_MVD_Support : Liver Shunt & MVD/HMD Support
they are so knowledgeable and know everything there is to know about it. Is your dog on medication and eating special food? If not, he needs to be right away. Go to that group. They will send you a form to fill out and send back and they can answer any questions. Here is Teddi's story:
Teddi's Story