Oh Maddie! I totally understand how worried you must be. I don't have any experience with liver problems. I have bred mine only once and didn't even know about the testing and all that until I became a member of YT. You have to do what you think is best for you and Lucas. If you trust your vet and they said to give him the supplement..maybe you should try that. I truly don't know but I certainly hope that everything turns out for the best for your Lucas. Please keep us informed. I do give mine(I have three) a supplement called Nupro, it has amino acids/protein in it. You can find it online, maybe you might want to read about it. It is suppose to be a very good supplement. They will also send you some free samples. Nuprosupplements.com Good luck sweetie