Just loved the information provided in this post

Milk Thistle comes for humans and also animals. The animal formula is a glycerine based formula....the human based formula uses an alcohol base. Be sure if you are using the Milk Thistle for your pet, you use the glycerine based formula. I am not sure you get the glycerine based formula if you buy it from GNC or at a human med shop....

As I said, I have given ALL my dogs this supplement, pulling my breeding females off the med at least two months prior to breeding...never had a problem. I use chemicals in my yard for fleas and ticks and ants, fertilizing the grass, killing weeds, and I dont want my dogs exposed to those chemical toxins. Never had a problem or issue. It is like everything else we choose to give our families.....you do your research, and you make your own decision if it is right for you. Milk Thistle works for us here!

Milk Thistle has certainly done no harm around here....the only "concern" I could possibly have is a waste of money giving something that is not doing anything at all for my dogs! My friend had a little dog years ago that was dying from liver disease and we used Milk Thistle on that baby, even giving it in enemas twice a day.....the vet said that kept that little dog alive for an additional year or more.... (I am not sure I would have opted to desperately try to save that baby's life at that point, it was excruciating to see that pup be that ill....I cant stand to see them suffer, but she just couldn't let that little dog go....).

I KNOW Milk Thistle is effective and works fabulously....and it has worked well keeping my dogs livers and kidneys, etc in tip top shape, from any chemicals they may pick up in the yard/neighbors yard/dog park, etc (for those of you that walk/socialize your dogs out in public!) Then there is the heartworm meds, flea meds/sprays/dips/etc......there are squirrels and possums and raccoons and armadillos and stray cats that come thru the yard, pooping and peeing.......and the stuff neighbors use for mosquitoes, the TruGreen chemicals used all over the neighborhood, etc. for those that walk your dogs......I am even watching my neighbor spray the cedar fence with some chemical that prevents mold and insect damage.....

Is this more as a treatment or preventative?

It is used as both.....my friend had her little dog, who was in the final stages of liver failure, on milk thistle.....I use it prophylactically to prevent any possibility of liver damage from heartworm meds, flea preventative, chemicals used on grass for insects/fertilizer, chemical used to spray yard for flea/tick prevention, etc., stuff my neighbors spray on our cedar fence for termites.....

I'm kind of shocked the human form has alcohol in it because it is given for cirrhosis of the liver. How about the powdered kind, why can't that be used for both. I'm actually thinking of taking it, it's may help with type 2 diabetes, but it does have a lot of warnings about it mimicking estrogen and that can be problematic. Here's some information on human usage:

Milk Thistle: Benefits and Side Effects