herbs and horses: “natural” healing?

HERBS AND HORSES: "NATURAL" HEALING?

David W. Ramey, DVM

For those that yearn for a more "natural" way to help sick or injured horses, herbs offer an undeniable al- lure. What could be more natural than using nature's own botanical products to help a horse recover from injury or disease? There's a long tradition of using herbs in healing, ranging from historical Chinese practices and Ameri- can Indian lore to the Thomsonian movement in the United States of the late 1700' s. Nonetheless, there are many issues involved with herbal medications that must be addressed before it can be assured that they are safe and effective therapies for horses.

When Herbs are Effective, There is a Reason

Advocates of herbal medicine point out that a significant percentage of today's medicines were derived from plants. This statement is true. For example, digitalis was originally derived from dried leaves of the foxglove plant (Digitalis purpurea); it has been used in the treatment of congestive heart failure. In 200 B.C., the Greek physi- cian Hippocrates prescribed the bark and leaves of the willow tree (rich in a substance first called salicin) to relieve pain and fever. (Some two thousand years later, a German chemist experi- mented with salicin and created salicyclic acid, which was stabilized by adding an acetyl-group in 1897.) Thus, while herbs may be effective medications, there is a reason why they

Author's address: PO Box 5231, Glendale, CA 91221

pharmacologic ingredient. Although it is true that some medi-

cines are derived from plants, that statement is also misleading. For one thing, herbs may contain a number ofbioactive substances. Using the above examples, the foxglove plant contains over thirty different glycosides which contain some cardiotonic properties. Each differs in potency, in time of onset and in dura- tion of activity. While willow bark may have some anti-inflammatory effect when chewed, it also contains large amounts of tannins, which make people sick if they chew too much of it. Unfor- tunately, at present, knowledge of the constituents of herbal medicines and their pharmacological and possible toxic effects is extremely limited. For example, about 7000 species of plants are used in China as herbal remedies but only 230 of the most commonly used ones have been subjected to in-depth pharmacological, analytical and clinical studies. 1

Further compounding the problem is that the active ingredient content of herbs in their natural state can vary greatly from batch to batch. For example, glycyrrhizic acid, one of the primary pharmacologic agents in licorice root occurs naturally in concentra- tion ranges on the average from two to 70%, with some rare plants as high as 27%. Glycyrrhizic acid can be toxic; differing concentrations of the active ingredient make accurate dosing impossible.

The fact that some herbs have active pharmacologic ingredients can be a problem for unsuspecting horse owners and trainers. There are numerous reports of positive drug tests resulting from the administration of commer- cially available herbal products to

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horses. For example: 1. Spinach octacosanol tablets were

shown to be contaminated with phenyl- propanolamine after a horse racing at Santa Anita tested positive for phenyl- propanolamine.

2. Numerous trainers in the US have been penalized for positive tests for caffeine after administering various herbal products containing guarana to their horses. (Guarana, made from the crushed seed of a climbing shrub native to Brazil and Uruguay, is used to prepare a hot beverage in those countries.) Some of these products are labeled "No added caffeine" although guarana is the obvious source of caffeine.

3. Some ginseng-containing herbal products are known to contain sufficient caffeine to produce a positive test.

4. Various herbal products contain alkaloids from Ephedra. Some of these, such as "Herbal Ecstasy" also contain caffeine. Laboratory reports indicating positive tests for ephedrine, phenylpro- pano lamine , pseudoephedr ine , norpseudoephedrine, and caffeine have been received by racing officials. 2

The Myth of "Natural" Many promoters of "natural"

herbal products promote the myth that they are somehow superior to the same products produced synthetically in a laboratory. In that regard, herbal products are often described as "better" because they are "natural." Such claims appear to border on mysticism. There is no scientific basis for them. A chemical is a chemical. For example, there is no difference in the vitamin C that is ob- tained from natural biosynthetic pro- cesses in rose hips and that which is made in the laboratory of a chemical manufacturer. The word "natural" im- plies only the source and does not indicate that the product is, in fact, superior. (However, it does seem to indicate that the consumer of such a product should be expected to pay quite a bit more for it.)

Nor does "natural" imply that herbal medications are safe. Many people think that herbal medicines, being natural, are also harmless? This is wrong. There is nothing about herbs that au tomat i ca l ly makes them non-toxic just because they are "natural." Natural toxins have the same mechanisms of toxicity as synthetic toxins. For example, cabbage and broc- coli contain a chemical whose break- down products act in the same manner as does dioxin, one of the most feared industrial contaminants. Dioxin is carcinogenic and teratogenic in rodents at extremely low doses; however, the doses ingested by humans are far lower than the lowest doses that have been shown to cause cancer and reproduc- tive damage in rodents. 4 One reason herbs may have a reputation for lack of toxicity may be because the concentra- tion of pharmacologic compounds in herbs is frequently very low. That is, very little of the active ingredient is actually being delivered in an herbal preparation; all toxic effects are dose related.

Drug receptors in the horse' s body cannot distinguish whether a molecule comes from a chemical laboratory or from the plant kingdom. The toxic potential of an herbal remedy does not depend on its origin; rather, it is related to the pharmacological characteristics and dose levels in its active ingredients. In fact, there should be no difference between the use and application of herbal medications and conventional pharmaceuticals.

Direct Health Risks of Herbal Remedies

Equine veterinarians should be fa- miliar with toxicities related to "natural" plants such as selenium accumula- tors like Senecio sp. There is a paucity of studies related to the effects of herbal products on horses. However, there are numerous documented examples of direct health risks from natural plants and

Dutch word drogge meaning =to dry," as pharmacists, physicians, and ancient healers often dried plants for use as medicines. But, in western medicine today the use of pure herbs in the treatment of disease and other health disor- ders is usually discouraged. Synthetic chemical replicas of the active ingredients are preferred.

In general, the effectiveness of most herbs is stdctly anecdotal. How- ever, the Wodd Health Organization (WHO) notes that of 119 plant-derived pharmaceutical medicines, about 74% are used in modem medicine in ways that correlated directly with their traditional uses as plant medicines by native cultures. 2

Herbal medicines work in much the same way as do conventional pharmaceutical drugs, which is through their chemical makeup. Usually their chemical effects are less dramatic than those of purified drugs administered by more direct routes, because the amount of the active ingredient administered is less. This has led proponents of herb use to believe that herbal medicine has most to offer when used to facilitate healing in chronic ongoing problems?

The United States Food and Drug Administration (FDA) was created with the philosophy that food and drug test- ing is financially feasible because a patent is provided to the company that successfully proves the worth and safety of a substance. This automatically ex- cludes unpatentable substances, thus putting herbal medicine outside the "sys- tem," in the United States. However, WHO recognizes that nearly 800 of the world population is dependent O n traditional medicine (based on historical practice) for primary health care. 2 Herbal medicine constitutes a large part of what is practiced as "traditional" medicine around the wodd. WHQ has published guidelines for the assessment of herbal medicines in an attempt to help the ministries of health of all govern- ments develop regulations that ensure medicines are labeled properly, and that consumers andpractitioners are given proper directions for their use. 3

According to one reference on al- temative medicine, 1 "Herbal medicine is more readily accepted Jn Europe than in the United States. T~e Bdtish Herbal Pharmacopoeia, though not officially recognized by Parliament, ts neverthe- less the accepted publication in the field. In Germany, the Ministry of Health has a separate commission that deals

Continued next page

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exclusively with herbal medicine. Ger- man doctors study herbal medicine in medical school, and since 1993, all physicians in Germany must pass a section on these medicines in their board exams before becoming licensed. As part of the unifying efforts going on among members of the European com- munity, European physicians, health professionals, and researchers have formed ESCOP, the European Scien- tific Cooperative for Phytotherapy. This organization is publishing monographs on individual herbs used in clinical medicine as well as those used for self- medication. These monographs, repre- senting the culmination of all the scientific information known on each herb, are published in the European Pharma- copoeia. It's one of several resources, including the German E Commission monographs and the sedes of books by Dr. Varro Tyler.

Herbal products are available in a vadety offorms: whole herbs; teas; cap- sules and tablets; extracts and tinc- tures; essential oils; or salves, balms, and ointments. ~Nhen treating chronic illness with herbal medicine it is extremely important to treat the entire body, as the illness may be simulta- neously affecting many systems of the body at vadous levels," according to Mary Bove, ND,LM, a who voices the philosophy of "traditional medicine. The course of the treatment must include nutritional, tonic, and restorative plants in conjunction with herbs that support the body's elimination functions."

There are and have histodcally been many different systems of herbology. Herbs are a part of traditional Chinese Medicine, where the cen- tral theme is restoration of harmony, and the treating of the whole body. The Chinese categorize herbs by taste: bit- temess, sweetness, acridity, saltiness, and sourness. Besides defining particular herbal tastes, the Chinese as- cribe different temperatures to herbs: hot, warm, neutral, cool, and cold. Ayurveda medicine has ancient roots in the Indian subcontinent. It holds that the taste of an herb is indicative of its properties. The Sanskdt word for taste, rasa, means "essence." There are six essences: sweet, sour, salty, pungent, bitter, and astringent. Today, most people classify herbs in a different manner, more closely related to pharmacological concepts.

Western medicine also has its roots in herbology. It is more likely to be

herbs in humans. Epidemiological studies from various parts of the world show that certain "natural" chemicals in food may be carcinogenic risks to humans. Chewing of betel nuts with tobacco has been correlated with oral cancer. 6 The phorbol esters present in the Euphorblacea, some of which are used as folk remedies or herb teas, are potent mitogens and are thought to be a cause of nasopharyngeal cancer in China, esophageal cancer in Curacao, 7,8 and have been shown to cause signs of general poisoning in lactating goats and their milk-fed kids. a Pyrrolizidine toxins are mutagens that are found in comfrey tea, various herbal medicines, and some foods; they are hepatocar- cinogens in rats, and may cause liver cirrhosis and other pathologies in humans. s Allergic reactions, toxic reactions, possible mutagenic effects, adverse effects related to an herb's de- sired pharmacological actions and drug interactions have been reported with various herbal preparationsJ TM

Indirect Health Risks Even in the absence of direct ad-

verse effects from herbal preparations, there are indirect risks from their use when use of an unproven herbal remedy delays or replaces an effective form of conventional treatment. This may happen either as a result of the provider of the therapy being overly optimistic in his or her abilities or when a true believer puts too much faith in the healing powers of nature. An example of indirect health risks in horses would be advocating the use of any number of natural remedies for the prevention and treatment of internal parasites (e.g., garl ic) , in l ieu of conven t iona l anti-parasitic agents. Unfortunately, no natural remedy has been shown to be effective in the control of equine internal parasites.

The use of herbal medicines also means that there is a potential f~r drug interactions between these preparations

and conventional "Western" medicines. There have been a number of interactions reported to date. These include papaya extract and warfarin and evening primrose oil and epileptogenic drugs (increased likelihood of seizures). How- ever, an interaction between two compounds is not always as expected. One would expect that the combination of ginkgo biloba and a thiazide diuretic would cause a hypotensive crisis. How- ever, an elderly human patient taking this combination was found to have elevated blood pressure, which returned to normal when both agents were stoppedJ 2 Herbal remedies have also been shown to reduce the effectiveness of concurrently administered conventional medicat ions. For example , co-administration ofphenytoin with an Ayurvedic syrup called "Shankha- pushpi" was reported to result in re- duced concentrations of phenytoin and loss of seizure controlJ 3 More studies on interactions between traditional and modern medicines are certainly needed.

Lack of Quality Assurance Herbs intended for preventive or

therapeutic use are not regulated as drugs under federal laws. Instead, these products are marketed as "foods" or "dietary supplements" without specific health claims. Since they are not regulated as drugs, no legal standards exist for the processing, harvesting, or pack- aging of herbs. Labels of herbal remedies generally do not list information about side effects , dangers and contraindications, nor do they discuss dosages. In many cases, contents and potency are not accurately disclosed on the label. The lack of regulations re- garding good manufacturing practices for these products and the lack of re- quirements for disclosure of all ingredients makes it virtually impossible to know what you are actually giving a horse when you give it an herbal supplement.

Even if it is possible to obtain

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accurate information and determine the proper dosage and route of administration of an herbal, there is yet another obstacle to overcome. Very few herbal medicines have both the scientific name of the herb and an expiration date marked on the bottle. Common names may be shared by several herbs, only one or two of which are medicinal. For example, the name snakeroot can be applied to at least six very different plants. Or ginseng: there are quite a few subspecies that have somewhat different properties and a wide variation in cost. Wild ginseng has been shown to have immunomodulating effects that are absent in the cultured root? 4 By using only the common name, a less effective or even completely non-medicinal herb may be substituted for the medicinal one.

Such substitutions can have tragic and even fatal results. At least i00 cases of extensive interstitial fibrosis of the kidneys were observed in Bel- gium in women who had followed a weight-loss regimen that included the use of Chinese herbs. It was shown that the prescribed Chinese herb called Stephania tetrandra was, in fact, inad- vertently replaced by another Chinese herb, namely Aristolochiafiangchi in the powdered extracts delivered in Bel- gium and in France. 15

On the other hand, some products do not contain any useful substances. It has been asserted that the more expen- sive the plant material, the more likely it is to be inferior. Studies16 have shown that many ginseng products do not contain any active ingredients? 1,17 Herbs such as burdock root, "cleavers" (derived from a climbing plant that is common in England), oregano and dande- lion have no known therapeutic value, although all of them are ingredients in an over-the-counter herbal "anti-itch" preparation sold to horse owners.

Adulteration Problems In addition to problems with herbs

themselves, there are numerous in- stances of reports of poisonings caused by herbal medications that were adulterated with pharmaceuticals, contaminants or erroneous substitutes for the primary herbal ingredient. Based on reports, the adulteration problem appears to be particularly significant in, but not limited to, Chinese herbal medications. Aplastic anemia has been reported from an herbal medication adulterated with phenylbutazone 1 a and acute interstitial nephritis has been reported from another herbal preparation adulterated with meclofenamic acid. a~ Cases of severe and even fatal poisoning have occurred after medication with herbs containing aconitine, podophyl- lin, heavy metals and anticholinergic substances.21-24 A recent survey of Chi- nese herbal medications found that an average of 23.7% were adulterated with everything from numerous non-steroi- dal anti-inflammatory drugs to caffeine. More than half of the adulterated products contained two or more adulterants.aS

Limitations of Traditional Experience

Many herbs have been used for thousands of years and folk healers and traditional herbalists have accumulated quite a bit of empirical information. However, folklore is not much help in detecting effects that occur years after an herb is used (such as cancer) or that occur only in a small percentage of people. Experience may be useful in identifying obvious and predictable acute toxicities; however, it is a much less reliable tool for detecting reactions which are inconspicuous, rare, develop gradually or have a prolonged latency period.

The risk that infrequently occurring adverse reactions to herbal remedies will remain unnoticed is illus- trated by the statistical "rule of three." This rule dictates that the number of patients treated must be three times as

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VETERINARY REVIEW

understood by scientists trained in pharmacology. The major difference in use of herbs between the Eastern views and the Western is that many people in today's Western societyview medicines as biochemical magic which should be expected to provide instant results. This often Is the case with acute illness, but has major limitations when it comes to chronic or degenerative disease.

David Hoffmann, past President of the American Herbalist Guild believes the future looks bdght for those who want to explore the benefits of herbal medicine. =There are profound changes happening in the American culture and herbal medicine, 'green medicine,' is playing an ever-increasing role in people's experience of this transforma- tion."

Footnotes

aMary Bove, ND, LM, head of the Department of Botanical Medicine at Bastyr College of Natural Health Sciences, in Seattle, Washington.

Further information can be ob- tained from the following orgeniza- tions:

American Association of Acupunc- ture and Oriental Medicine, 4101 Lake Boone Trail, Suite 201, Raleigh, NC 27607; (919) 787-5181.

American Association of Naturo- pathic Physicians, 2366 Eastlake Av- enue, Suite 322, Seattle, WA 98102; (206) 323-7610.

The American Herbalist Guild, PO Box 1683, Sequel, CA 95073.

Herb Research Foundation, 1007 Pearl Street, Suite 200, Boulder, CO 80302; (303) 449-2265.

References 1. Alternative Medicine: The

Definitive Guide; Compiled by The Burton Goldberg Group; Future Medicine Publishing.

2. Farnsworth NR, et al.: Medicinal Plants in Therapy. Bul World Health Org 1985;63(6):965-981.

3. Akerele O: "Summary of WHO Guidelines for the assessment of herbal medicines." HerbalGram 1992;28:13--16.

high as the frequency of an adverse reaction to have a 95 per cent chance that the reaction will actually occur in the studied population. Thus, if an adverse reaction occurs once in 1000 times, the healer would have to treat at least 3000 patients to be 95 per cent sure that he or she will see one reaction. However, the healer may need to see more than one reaction before a mental connection with the remedy is made. To have a 95 per cent chance of seeing a reaction three times, the healer would have to treat 6,500 patients with the same remedy, or approximately one patient a day for almost 25 years. 26

Herbs vs. Drugs When pharmaceutical substances

are discovered in plants, drug companies try to isolate and synthesize that substance in order to provide a reliable supply. They also attempt to make derivatives that are more potent, more predictable and have fewer side effects. If herbal products were really as effective as the derivatives patented by the drug companies (and they have had thousands of years to "prove" their worth), there would be no need for a pharmaceutical industry. Competing companies would sell the natural products without the need to pay licensing fees. However, pharmaceutical derivatives of herbs are likely to be either more active, more selective or have fewer adverse side effects than the natural product and drug products contain specified amounts of active ingredients.

Although there is a growing body of scientific literature on herbs, studies to determine whether particular compounds are teratogenic or carcinogenic are exceedingly rare. It is virtually impossible to find research comparing different amounts of a particular herb to find the optimum treatment dose. Very few herbs have been tested to determine the plasma peak ~r the half-life of their active ingredient(s).

Studies or reports on interactions with drugs, foods or other herbs are virtually unknown. The clinical practitioner who intends to use herbal remedies is in the position of looking at the herb's main mechanism of action, making assump- tions about product content and then using his or her general pharmacology knowledge to try to spot potentially hazardous interactions and hoping for the best. It leaves the layperson who is trying to self-treat completely in the dark.

Recommendat ions for Rational Use of Herbal Medications

The National Council for Reliable Health Information, a non-profit consumer advocacy group, has made a number of recommendations that would help overcome some of the numerous problems with herbal medicines. They suggest that a special category of OTC medicines called "Traditional Herbal Remedies" (THRs) be established and regulated as follows:

1. Labels must alert consumers to the fact that herbal remedies are held to a lower standard than that applied to standard medicines.

2. Limit THR products to those with properties sufficiently documented in the pharmacognosy (the science of medicine from natural sources) literature to assure an acceptable measure of safety and efficacy.

3. Limit herbal remedy products to those known not to have lethal or dam- aging side-effects when taken in over- dose, or over an extended time period.

4. Limit THRs to the treatment of nonserious, self-limiting ailments.

5. Require THR remedies to meet the same labeling standards for all drug products.

6. Require plant sources to be identified by their scientific names.

7. Require that all active ingredients be quantitatively and qualitatively identified on the label.

8. Require herbal remedy products


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to contain sufficient amounts of pharma- cologically active substances for the product to perform as expected. Only those expectations that can be supported by science should be permitted on labels.

C O N C L U S I O N

To make a rational decision about an herbal product, one would need to know what active ingredients are contained in the herb, its safety and side-effects and whether the herb has been shown to be as good or better than pharmaceutical products available for the same purpose. This information is incomplete or unavailable for most herbal products. Furthermore, much of the easily accessible information about herbs appears to be unreliable. Practi- cally all literature promoting herbal use in horses is based on hearsay, folklore

and tradition. The only criterion that seems to be avoided is scientific evi- dence.

Varro E. Tyler, PhD, former dean of the Purdue University School of Phar- macy and a leading authority on pharmacognosy has observed that more misinformation about the safety and efficacy of herbs is reaching the public currently than at any previous time, including the turn-of-the-century hey- day of patent medicines. Two of Dr. Tyler' s books (The Honest Herbal and Herbs of Choice) 16,a7 summarize what is known about many commonly used herbs. Dr. Tyler warns that consumers are "less likely to receive value for money spent in the field of herbal medicine than in almost any other. "27 The fact is, with safe and effective pharmaceutical products available, treatment with herbs rarely, if ever, makes sense.

R E F E R E N C E S

1. Chang HM, But PP: Pharmacology and applications of Chinese materia medica. World Scientific, Singapore, 1987; Vol 1 and 2.

2. Sams R, Professor, Analytical Toxicology Department, College of Veterinary Medicine, The Ohio State University, 1998. Personal Communication.

3. Ernst E: Complementary Medicine: common misconceptions. J R Soc Med 1995;88:244-247.

4. Ames B, Profet M, Gold L: Nature's chemicals and synthetic chemicals: Comparative Toxicology. Proc Natl Acad Sci July 17, 1990.

5. International Agency for Research on Cancer: (1988) LARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Overall Evaluations of Carcinogenicity: An Updating of I-ARC Monographs Volumes 1-44, Supplement 7 (IARC, Lyon, France).

6. Hirono I: ed. Naturally Occurring Carcinogens of Plant Origin: Toxicology,

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Pathology and Biochemistry, Bioactive Molecules,vol. 2. Tokyo/Amsterdam: Kodansha/Elsevier Science Publishers B.V., 1987.

7. HiravamaT, etal.: A new view of the etiology of nasopharyngeal carcinoma. Prev Med 1981 Sep;10(5):614-622.

8. Hecker E: Cocarcinogenesis and tumor promoters of the diterpene ester type as possible carcinogenic risk factors. J Cancer Res Clin Onco11981 ;99(1-2):103- 124.

9. Nawito M, et al.: Dietary cancer risk from conditional cancerogens in produce of l ivestock fed on species of spurge (Euphorblaceae). II. Pathophysiological investigations in lactating goats fed on the skin irritant herb Euphorbia peplus and in their milk-raised kids. J Cancer Res Clin Oncol 1998; 124(3-4): 179-185.

10. Bateman J, et al.: Possible toxicity of herbal remedies. Scott Med J 1998; Feb;43(I):7; 15.

11. Ernst E: Harmless herbs? A review of the recent literature. Am J Med Feb; 1998; 104(2):170-178.

12. Shaw D, et al.:Traditional remedies and food supplements: A 5-year toxi- cological study (1991 -1995). Drug Saf Nov;

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1997;17(5) 342-356. 13. Dandekar UP, et al.: Analysis of a

clinically important interaction between phenytoin and Shankhapushpi, an Ayurvedic preparation. J Ethnopharmacol 1992;35:285-288.

14. Mizuno M, et al.: Differences in immunomodulating effects between wild and cultured Panax ginseng. Biochem Biophys Res Commun May; 1994;16.200 (3): 1672-1678.

15. Vanherweghem L J: Misuse of herbal remedies: the case of an outbreak of terminal renal failure in Belgium. J Altern Complement Med 1998;4(I):9-13.

16. Tyler V: Herbs of Choice: The Therapeutic Use of Phytomedicinals, New York: Pharmaceutical Products Press. 1994;5.

17. Cul J, et al.: What do commercial ginseng preparations contain? Lancet 1994 Jul 9;344(8915):134.

18. Liberti LE, Der Marderosian A: Evaluation of commercial ginseng products. J Pharm Sci 1978 Oct;67(10): 1487-1489.

19. Nelson L, Shih R, Hoffman R: Aplastic anemia induced by an adulterated herbal medication. J Toxicol Clin Toxicol

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1995;33(5):467-470. 20. AM AB, et al.: Chinese herbal

medicine induced acute renal failure. Arch Intern Med 1995 Jan 23;155(2):211-212.

21. Chan TY, et al.: Chinese herbal medicines revisited: a Hong Kong perspective. Lancet 1993;342(8886- 8887):1532-1534.

22. Chan TY, Critchley JA: Usage and adverse effects of Chinese herbal medicines. Hum Exp Toxicol 1996 Jan;15(I):5-12.

23. ChanTY:Anticholmergic poisoning due to Chinese herbal medicines. Vet Hum Toxicol 1995 Apr;37(2):156-157.

24. But PP: Herbal poisoning caused by adulterants or erroneous substitutes. J Trop Med Hyg 1994 Dec;97(6):371-374.

25. Huang WF, et al.: Adulteration by synthetic therapeutic substances of traditional Chinese medicines in Hong Kong. J Clin Pharmacol 1997;37:344-350.

26. DeSmet, PAGM:An introduction to herbal pharmocoepidemiology. J Ethno- pharmacol 1993;38:197-208.

27. Tyler V: The Honest Herbal. New York: Pharmaceutical Products Press, 1993, 7.

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herbs and horses: “natural” healing?

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