This is a great article that explains what type of protein is good for dogs with liver disease and which ones to avoid. Red meat, for instance, produces high amounts of ammonia and should be avoided. Cod and cottage cheese actually have enzymes that heal the liver.
Liver | B-Naturals.Com Newsletter
Lady has liver damage from years of seizure medications and is on a home cooked diet. All the protein comes from white fish like cod or pollack, and dairy products like cottage cheese, yogurt and eggs.
Again, I would not add supplements or make any change in diet until after she has her BAT or it could skew the results.