Has anyone successfully reversed liver disease in their dog?

I'm sorry to hear about your dog. Unfortunately there are many medications that can cause liver failure. Phenobarbital is one of them. The nice thing about the liver is that it does regenerate if given the chance. You still might want to have an ultrasound done to rule out a liver tumor. Also has the chest and abdomen been x-rayed? If you can remove the cause of the liver failure there is a chance that your dog might recover.