Nice, but very general without any comment to the quality of the herbal material or herbal products:
this is the main problem of herbal products for human and animal use in US (already acknowledged by the US authorities) that quality control is lacking. There is such a high phytochemical polymorphism within most of the species that indicating the use of a plant (species) is insufficient if the chemotype is not known and there is no description of the substance - effect relationship. The future of herbal use in animals depends on quality assessment and quality assurance.
Good article about herbal products for equines. As an equine nutritionist I never fully discount the areas written of even though I have taken the opposite approach to feeding. If I were to be given furhter information as to how or why these products work in the equine field then I may even become more open to them. I also know there are several anti-nutritional factors involved in a few of the products mentioned and would actually hesitate in their recommendation for various reasons the least of which would be owner irresponsibility in administration.