Many plants synethesize biologically active substances and the practice of herbal medicine in pets is based on the use of plants and plant extracts to maintain the health of animals. Herbs are typically classified as Western or Chinese. Herb combinations have been developed for certain disease syndromes and should only be used under the guidance of a trained veterinarian. Always tell your veterinarian what medications, herbs, and supplements your pet may be taking as certain therapies may interfere with the absorption or action of another. Herbs, although natural, can cause adverse or toxic effects if used inappropriately.