Is your dog or cat suffering from liver failure, or have you just found out there is an elevation in their liver enzyme levels? Milk thistle, or an extract thereof, may prove to be helpful. In fact, milk thistle may help with that case of pancreatitis or diabetes. Milk thistle has also been found to have protective properties in those animals receiving chemotherapy or radiation treatments. In addition, milk thistle may slow down or stop the growth of certain tumors. Also, in the unlikely chance your pet consumes toxic mushrooms, milk thistle may have just the extract to save them. Milk thistle also has the ability to protect other organs besides the liver from the effects of radiation and chemotherapy. Additionally, milk thistle helps the body maintain hemostasis with chronic disease and when taking antibiotics.

Milk thistle was originally native to Southern and Western Europe where its seeds are typically harvested in late summer. Historically, the leaves were consumed in Europe and are said to be similar to spinach once the spines have been removed, while the fruit was eaten much like an artichoke. The main active constituent of milk thistle is silymarin or silybin.

Milk thistle, also known in Chinese medicine as "shui fei ji", is best known for treating chronic liver problems. In Germany, milk thistle is known as "mariendistel" and in France it is known as "Chardon-Marie". Additional commonly used names include "the Holy thistle", "St. Mary’s thistle" or "wild artichoke".

Gentamicin, a potent antibiotic, is well known for its adverse affects on the kidney (nephrotoxicity). Milk thistle has potent antioxidant actions which decrease the toxicity incurred through the use of gentamycin. Milk thistle also promotes kidney function in patients with end-stage diabetic nephropathy. In addition, milk thistle will slow down calcium metabolism and stabilize mast cells, which are important inflammation mediators.

Silymarin has been known to decrease the activity of some tumor promoters.

Milk thistle aids liver repair and detoxification by four different mechanisms: first is the antioxidant action which scavenges free radicals. Silymarin increases glutathione production by the liver, intestines, and stomach. Glutathione is used for detoxification cells in the liver. Silibinin decreases hepatic and mitochondrial glutathione oxidation which is seen with iron overload, and it is a mild chelator of iron. Secondly, it stabilizes the cell membrane and permeability of hepatocytes (liver cells) by inhibiting lipid peroxidation. Silymarin appears to alter the outer membrane of liver cells, inhibiting the entrance of hepatotoxins (liver toxins) and blocking toxin-binding sites. Thirdly, milk thistle also promotes ribosomal RNA synthesis by stimulating RNA polymerase, thereby increasing ribosomal protein synthesis, which in turn increases the ability of the liver to regenerate. In cases of toxin and drug induced hepatitis, alcoholic liver disease, viral hepatitis, and cirrhosis, milk thistle decreases aminotransferase activity. Finally, milk thistle slows the onset of cirrhosis arising through collagen deposition. Although not
fully substantiated, it is believed that silymarin will decrease the hepatic synthesis of cholesterol.

Milk thistle is used as an adjunct for chemotherapy treatment to reduce side effects.

Silymarin has led to a reduction in the incidence of some tumor types including those of the colon, tongue, liver, and bladder. Milk thistle and its extracts have also been shown to hold back the growth of the human prostate and of lung cancer in a mice model.

Extracts of milk thistle have been demonstrated to help prevent death in cases of severe Amanita mushroom poisoning when given intravenously.

Milk thistle extracts also protect the kidneys from radiation injury. When combined with omega-3 fatty acids, milk thistle has been shown to reduce the occurrence of radionecrosis cited in cancer patients receiving radiation therapy, and has shown to prolong the survival of patients receiving treatment.

Milk thistle has been shown to potentate the antitumor effects of drugs like cisplatin.

Silybin has been shown to mitigate damage from amylase secretion with pancreatic disorders. Silymarin administration was also demonstrated in a 1997 study to decrease fasting blood glucose levels, glycosuria, and insulin needs when used with diabetes.

The primary adverse affects of milk thistle may be in inhibiting certain chemotherapeutic agents and the possibility of promoting mammary tumor growth (breast cancer) in two rodent models. The stimulation of mammary tumor growth is thought to be due to the stimulation of estrogen receptors by silymarin. Silymarin should be used with caution in cases of breast cancer.

A nutritional supplement produced by Nutramax laboratories incorporates the use of silybin A and B in a product called Denamarin®. Denamarin® is marketed for the protection against oxidative stress. The drug is professed to promote hepatocyte protein synthesis and liver cell regeneration while inhibiting leukotriene production. Used as a liver supplement, it also improves bile flow in cats. The supplement should be given on an empty stomach for maximum absorption.


References:

LaGow, Bette, Editor. PDR for Herbal Medicines. 3rd Edition. 2004. Pp. 566-570.

Robinson, Narda. “Multi-Talented Milk Thistle”. Veterinary Practice News. March 2008. P. 24.

Wynn, Susan, and Barbara Fougere. Veterinary Herbal Medicine. Mosby 2007. Pp. 599-603.