How Effective Are Liver-Protecting Supplements?

My dog, Ozzie, was on Rimadyl for arthritis for less than a month with devastating effects to his liver. After two days in emergency with...

Dr. Eric Barchas  |  Nov 2nd 2011

My dog, Ozzie, was on Rimadyl for arthritis for less than a month with devastating effects to his liver. After two days in emergency with intravenous antibiotics and fluid, he recovered enough to come home. With a restricted diet and Denamarin daily, his liver levels are back to normal.

What do you know about the supplements Denosyl and Marin? I have been doing some studying and am considering switching him over to these instead of prescription Denamarin, which is very costly.

I do not want to mess with the success we are having but am open to other options. I would really appreciate your input.

Warm regards,


Glenolden, PA

Rimadyl, like virtually every drug and dietary supplement, is metabolized by the liver and excreted by the kidneys. Unfortunately, it has been linked to sudden liver injury and failure in rare dogs. I am sorry to hear that Ozzie was one of them, but I am happy to hear he survived.

Denamarin contains two purportedly active ingredients: S-Adenosyl Methionine (also known as SAM-e or Denosyl) and silybin (also known as Marin). In theory, these two agents help to prevent and reverse liver damage, and to support liver function. I should remind you that, as Homer (Simpson) pointed out, in theory communism works.

Granted, the theory behind these supplements seems pretty solid. And most medical and veterinary professionals accept their efficacy. But I also should remind you that for much of history, medical professionals accepted the efficacy of bleeding patients to balance the body’s levels of black and yellow bile to cure melancholic excess.

My issue with SAM-e, silybin, and nutritional supplements in general is that I have yet to see a solidly designed, nonbiased, peer-reviewed, double-blinded study that proves they do what they’re supposed to. It’s not like it’s hard to prove something works — if it works. Want to design a study to prove that antibiotics cure strep throat? Piece of cake. How about one to prove that condoms prevent the spread of HIV? No problem.

But why isn’t there a study that shows, unequivocally, that these supplements work? Maybe there’s some sort of complicated conspiracy (although I don’t understand why Big Pharma would conspire to suppress a potential blockbuster drug that could make billions). Or maybe the supplements don’t really do anything, which is why they’re relegated to the unregulated underbelly of dietary supplements, rather than being a part of the licensed and lucrative (but regulated) world of legitimate pharmaceutical agents.

Maybe the Denamarin helped Ozzie’s liver recover from the damage it suffered as a result of Rimadyl administration. Or perhaps the liver’s remarkable natural regenerative capacity did the work on its own. But I have digressed from your question.

From the information I have seen, a separately purchased combination of SAM-e and silybin appears likely to be just as effective (or ineffective) as Denamarin. But if his liver has recovered, he probably doesn’t need any further treatments or supplements whatsoever.

Photo: this liver is beyond repair.