Here is Dr. Dodd's recommended dosage for Milk Thistle from her
Healthy Pets newsletter:
Dog's size Dose as % of adult human dose
5 lbs 10%
5-10 lbs 15%
11-20 lbs 20%
21-40 lbs 30%
41-70 lbs 50%
71-100 lbs 75%
100 lbs 100%
Newer studies have found that milk thistle should be given along with Vitamin E for best results. Marin is really a better way to give milk thistle now. I get mine from Entirely Pets:
http://www.entirelypets.com/marindog..._utmk=32937215