Milk thistle or silymarin is a liver cleanser, detoxifier and repairer.  
Use it for liver or kidney damage, hepatitis, jaundice, and parvovirus recovery. it may be helpful in chronic skin disorders, tumors and cancer.  I give it to several of my pets daily.  
This is a major antioxidant.  Pets that have been on a lot of veterinary drugs, heartworm prevention or medication, vaccinations, deworming drugs or chemotherapy need this herb for healing.