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Laminitis: New Research on Milk Thistle, SilymarinBy Kentucky Equine Research Staff · November 24, 2014

There is no shortage of supplements designed for virtually any ailment a horse could suffer—joint disease, digestive problems, skin issues, and laminitis. Many of those supplements have only a limited amount of science supporting their use; however, Austrian authors recently published an article* supporting the use of milk thistle and silymarin for horses with laminitis.

“Laminitis is a devastating disease with multiple causes including colic, diarrhea, and trauma,” explains Kathleen Crandell, Ph.D., equine nutritionist at Kentucky Equine Research in Versailles, Ky.

Crandell adds, “Milk thistle and silymarin, which is an extract of milk thistle, have shown anti-inflammatory and antioxidant properties, and are included in some equine hoof supplements.”

The exact physiological steps involved in laminitis remain somewhat unclear, which makes finding an effective treatment strategy challenging. Bacterial toxins, such as lipopolysaccharides (LPS), are believed to be involved in the development of laminitis. One antibiotic, polymixin B, is known to bind LPS and therefore could be used (at least theoretically) to either prevent or minimize the severity of a bout of laminitis. Polymixin B, unfortunately, has many severe side effects and its use in horses is therefore limited.

To determine if milk thistle and silymarin could serve as safer alternatives, researchers used laboratory-based tests to put those supplements through their paces. Key findings of the study included:

  • In their model of laminitis, LPS consistently had negative effects on lamellar (hoof) tissues;
  • As expected, polymixin B was an effective binder of LPS, neutralizing almost 100% of the LPS; and
  • Both milk thistle and silymarin also neutralized LPS, but less than polymixin B. Silymarin was much more effective than milk thistle and closer to polymixin B in its ability to neutralize LPS.

These positive results add to the overall body of evidence-based medicine on the role of nutritional supplements in equine medicine. The authors also noted, “A crucial point that should be considered when feeding [milk thistle] is the actual content of silymarin…in the administered product.” Additional studies are therefore warranted to help determine ideal doses of milk thistle and silymarin for both the prevention and treatment of laminitis.

*Reisinger, N., S. Schaumberger, V. Nagl, et al. 2014. Milk thistle extract and silymarin inhibit lipopolysaccharide induced lamellar separation of hoof explants in vitro. Toxins (Basel) 6(10):2962-2974.