I have an mvd dog she tested post 76, 54 then on low protein 26 her alt was normal like your dog. She has horrible allergies and is hypothyroid and she is on soloxine twice a day and temarilp every other day and for 3 years has had normal alt even on those drugs with NO SUPPORT of milk thistle or sam-e and no symptoms ever just came up when we were trying a drug atopica so before giving the drug he wanted bats done on her -
Has your dog had any symptoms? If not i seriously would not stress. If no symptoms i would put on 22% protein and if symptoms 18% - due to dd allergy issue I cannot supplement - I will say a family member of ours works for NIH in washington dc and she has a liver issue. I told her about milk thistle and sam-e so she did a ton of research for herself and she came up with milk thistle was safe but she does have some question marks due to data about sam-e so she will not take it and this was shocking to me as i usually recommend that in liver dogs but had to say something since she brought it to my attention since she is a researcher at national institute of health in washington dc and knows her stuff and many of her friends are human doctors. The other thing is you have to be careful with sam-e and anti-depressants as well as pain meds and i believe it is tramadol you should not mix with sam-e see link
Tramadol