Risks associated with the use of herbs and other dietary supplements.

The use of dietary supplements (herbs, vitamins, minerals, amino acids, enzymes, and other compounds) is common in horses. They are heavily marketed in retail stores, magazines, and on the Internet. There is the perception that since these compounds are "natural" they are devoid of toxicity, and, therefore, they are safe to use. Some of the active compounds in supplements, however, have inherent toxicity, and using them may cause adverse effects. Even relatively non-toxic ingredients may be toxic if used over-zealously or for a long period of time. By and large, these compounds have not been tested for safety or efficacy when used as marketed, and, unfortunately, there is little regulatory oversight for such products. Other deleterious consequences of dietary supplement use include interaction of compounds in the products with conventional drugs, resulting in unexpected adverse effects, or the occurrence of violative residues in urine samples collected from show or performance horses. This article provides a brief overview of potential problems associated with dietary supplements, primarily focusing on products containing herbs and essential oils.