I'm so sorry
First off, find out how the blood work goes...Usually in liver failure, Bilirubin is very high, Albumin is low, etc.
Does your baby look like he has jaundice? That's another sign...The accumulation of fluid in his belly is called ascites and is consistent with liver disease...
Has your boy been losing weight or lost his appetite?
My yorkie has liver disease, and we have him on a vegetarian diet, lactulose, milk thistle and denosyl (to help protect his liver), etc. We also feed him small frequent meals to help lighten the load on the liver...
Liver Disease Signs, Symptoms, and Diagnosis
Prayers for your baby boy!!