Silymarin is a nutraceutical derived from the seed of the milk thistle plant, not to be confused with blessed thistle. It’s antioxidant properties and ability to scavange free radicals have been used to treat a variety of liver diseases in humans, dogs and cats. Although most of the studies with silymarin were conducted in humans and then extrapolated back to animals, I did manage to find a few interesting studies performed in animals. In 1984, Dr. Vogel and associates found that dogs given silymarin before ingesting poisonous mushrooms had fewer clinical signs and better prognosis than those left untreated. Another study by Dr. Avizeh and associates found that silymarin protected cats against liver damage caused by acetaminophen. Unfortunately, silymarin showed mixed results in protecting pigeons from B1 aflatoxins.
Recently, silymarin is being used to lesson unwanted side effects with some chemotherapy protocols. Several years ago, I diagnosed an elderly cat with lymphoma throughout its intestines and referred her to a veterinary oncologist for treatment. The oncologist placed the cat on milk thistle during chemotherapy which seemed to help.
High doses of milk thistle may cause vomiting, diarrhea and/or anorexia. Some animals may also become allergic to the plant. Dosing milk thistle can be challenging because of the variety of formsit comes in; extract vs dried plant. Therefore, always consult your veterinarian before using any nutraceutical.
-Avizeh, R et al. Evaluation of prophylactic and therapeutic effects of silymarin and N-acetylcysteine in acetaminophan-induced hepatotoxicity in cats. J. Vet Pharmacol Ther. February 2010; 33(1): 95-9.
-Grizzle, J. et al. Effects of dietary milk thistle on blood paramenters liver pathology, and hepatobilliary scintigraphy in white carneaux pigeions (Collumbia livia) challenged with B1 aflatoxin. J. Avian Med Surg. June 2009; 23(2): 114-24.
-Plumb, D Plumb’s Veterinary Drug Handbook 7th Ed., John Wiley & Sons, 2011
-Twedt, D. Nutraceuticals in Liver Disease, ACVIM 2004.
-Vogel, G. et al. Toxicology and Applied Pharmacology 1984; 73(3): 355.