Medical Herbalists use liquid herbal extracts from beneficial plants. The active ingredients are converted from a solid (the plant) to a liquid. They are more concentrated and more absorbable. The substances in the formula pass through the intestines easily and enter the horse’s bloodstream directly. A dried herb will first have to be digested by the correct intestinal bacteria. That takes longer and some of the components can be lost. In addition, the concentration of active ingredients is much higher in extracts. 
Natures Farmacy's Stringhalt support tonic contains the following Medical grade herbal extracts;
St Mary's Thistle, Chamomile *, St. Johns Wart, Oats Seed, Nettle, Saw Palmento, Turmeric and Rosehips. 
*- Herbal extracts marked with * are swabbable and are not suitable for competiton use. If you require a non swab version of this, please select from the Drop down menu.