I am so sorry your Buddy is so sick. A liver shunt can be repaired surgically if that is what this is. In the meantime it is important to find out how to treat him. Did your vet put him on a special diet or anything until the testing can be done?
There are many members here who have liver shunt pups....they will be along to share their experiences.
Glad you found Yorkie Talk!
You will get lots of help and Buddy will have a lot of prayers.