Objective

At the end of this session attendees will be aware of the growing evidence base of herbal medicine and be able to find and access the evidence to assist them in practice.

Background

Why use an herb when we have well-researched, established medicines for many veterinary conditions? Where a conventional medicine is both safe and effective, it makes sense to use them. However, for many conditions drug use isn't safe and not always effective; chronic diseases are chronic because the medicine, while targeting specific biochemical pathways, is not necessarily curative. And while we currently have good treatment options we are still challenged by diseases like cancer, allergies, autoimmune and degenerative diseases in animals. As well the rising issues of multiple drug resistance in particular mean that for all these reasons, the potential use of herbal medicines deserve consideration.

Herbal medicine in the modern veterinary setting is an emerging science. It represents the synthesis of many fields including botany, pharmacology, pharmacognosy, philosophy, history, pathology, ethnoveterinary medicine, research, clinical practice and monograph study. The central issues in veterinary herbal medicine today are safety and efficacy. While safety of many herbs has been demonstrated (through traditional use and science) in people and laboratory animals, safety of most medicinal herbs in domestic animals is still largely unknown, though, based on experience surprisingly few adverse events have been observed. Like human herbal medicine the safety, potency and quality of herb products and therefore the regulation and the registration of herbal products is a daunting issue. As practitioners, we need to draw on traditional knowledge, our clinical experience and a scientific rationale for the application of our herbal medicines.

So where do we find the evidence?

Traditional Use by the Profession in the West

The use of herbal treatments within veterinary medicine is not a new phenomenon, nor has it always been considered alternative! Ever since veterinary medicine as a discipline began in Europe in the 17th and 18th century, plants have been an important part of veterinary herbal medicine. In fact herbs were considered orthodox within the veterinary profession. These include herbs such as ginger, aloe, peppermint, cascara, senna, betel nut, calabar, catechu, kamala, fern, and others that feature in the veterinary pharmacology texts and veterinary medical texts into the 1960s. Old veterinary text books dating back to the late 1700s, 1800s and early 1900s provide a source of relevant information on experience based use of many herbs for the treatment of cattle, horses, pigs and dogs.

Scientific Proof

There are in fact, over 25000 citations for herbal medicine on PubMed. Over 2000 rigorous clinical studies, over 3000 systematic reviews and a growing number (243) of meta-analyses on herbs in the literature (compared to 201 meta-analyses in veterinary medicine). These citations are mainly in human medicine, with a small and growing number (3700) citations in using herb and animal as search terms especially in poultry and production animals. But this volume of data is still small considering the multitude of herbal medicines being used worldwide with several thousand different plants being used for medicinal purposes. The relative paucity of rigorous clinical trials in veterinary medicine is mostly due to the fact that, compared with the pharmaceutical sector, the companion animal herbal industry is small and can rarely afford the considerable expense of a clinical trial and support in university settings competing for research funds is limited, especially in the field of "complementary medicine."

However, there have been a surprising number of research studies performed on cats, dogs and some large animals, and thousands on rats, mice, rabbits and guinea pigs. Numerous randomized double blind clinical studies have been undertaken on single herb extracts since the 1980s many using animals as models for study. Meta-analyses have been undertaken on the herbs Ginkgo biloba, St. John's Wort (Hypericum perforatum) and Saw palmetto (Serenoa repens) as examples. Gingko leaf extract was developed in the 1950s in Germany to treat memory loss. This use is now supported by pharmacological evidence (in dogs)¹ as well as clinical trials, and more recently its use in cognitive dysfunction in dogs is also supported².

These clinical studies combined with an enormous number of laboratory studies both in vivo and in vitro on herbs and herbal extracts, explain the mechanisms of action and efficacy for a large number of herbs. As early as 1854 marshmallow (Althea officinalis) was used for respiratory conditions in animals as an antitussive. A study using cats as a model showed antitussive activity in 1992³ and the study was repeated in 2007⁴ providing evidence and informing veterinary herbalists of its potential use in cats post-extubation and for other respiratory challenges.

None the less, some exciting studies are influencing veterinary medicine today including one on the polysaccharide extract of the herb Coriolus versicolor for improving quality of life outcomes in dogs with hemangiosarcomas⁵ in a randomized placebo controlled multidose pilot study and a recent study supporting the widespread use of a formula called Yunnan Bai Yao in an in vitro study supports its anticancer mechanism in canine hemangiosarcoma cell lines⁶.

Some other recent studies (from 2014) available on pub med include:

There is also a body of published research in journals in France, Italy, Germany, India, China and elsewhere in the world. The extent of the available information and quality of the information is difficult to judge due to language and access constraints.

Many of the published efficacy studies are available on PubMed or Medline available on http://www.ncbi.nlm.nih.gov/entrez and also Google Scholar. Authoritative reviews of herbal efficacy can be accessed in the Cochrane reports at www.cochrane.com (VIN editor: link modified 2/10/16) and the European Scientific Cooperative on Phytotherapy (ESCOP) http://www.escop.com is an international network of scientists and physicians, who have published material submitted to the central European medicines regulatory authorities. Another database that ranks herbal efficacy according to the rigor of the studies is available on natural standards database http://info.therapeuticresearch.com/natural-medicines. Many of these studies confirm that whole plant extracts have more than a dietary supplement effect, that they can have efficacy on a particular disease and set of symptoms.

We often reach back into tradition and see how herbs were used and look to science to explain their rationale. While the evidence base is small, the evidence from multiple sources can readily inform the educated practitioner on appropriate use of plant medicines in integrative veterinary practice thereby expanding our treatment options.

Resources

Organizations providing journals and education.

www.civtedu.org for short courses to accredited qualifications in Western and Chinese herbal medicine.

The Veterinary Botanical Medicine Association www.vbma.org international membership with veterinarians with a special interest in herbal medicine.

www.ivas.org provide education in Chinese herbal medicine.

Websites

http://www.ncbi.nlm.nih.gov PubMed for abstracts of journal articles.

Journals

Contemporary Veterinary Texts for Small Animal Practice.

Veterinary Herbal Medicine. S Wynn and B Fougere. Elsevier; 2006.

Dr Steve Marsdens Essential Guide to Chinese Herbal Formulas. www.civtedu.org

Integrating Complementary Medicine into Veterinary Practice. Broadfoot P, Palmquist R, Johnston K, Wen J, Fougere B. John Wiley and Sons; 2009.

References

1.  Shen M, Lu Z, Ye Q. [Effects of an extract of Ginkgo biloba on the blood flow of brains and back legs of dogs] [Article in Chinese]. Zhong Yao Cai. 2000;23(12):764–766.

2.  Reichling J, Frater-Schröder M, Herzog K, Bucher S, Saller R. Reduction of behavioural disturbances in elderly dogs supplemented with a standardised Ginkgo leaf extract. Schweiz Arch Tierheilkd. 2006;148(5):257–263.

3.  Nosál'ova G, Strapková A, Kardosová A, Capek P, Zathurecký L, Bukovská E. [Antitussive action of extracts and polysaccharides of marsh mallow (Althea officinalis L., var. robusta)] [Article in German]. 1992;47(3):224–226.

4.  Sutovska M, Nosalova G, Franova S, Kardosova A. The antitussive activity of polysaccharides from Althaea officinalis L., var. Robusta, Arctium lappa L., var. Herkules, and Prunus persica L., Batsch. Bratisl Lek Listy. 2007;108(2):93–99.

5.  Brown DC, Reetz J. Single agent polysaccharopeptide delays metastases and improves survival in naturally occurring hemangiosarcoma. Evid Based Complement Alternat Med. 2012;2012:384301.

6.  Wirth KA, Kow K, Salute ME, Bacon NJ, Milner RJ. In vitro effects of Yunnan Baiyao on canine hemangiosarcoma cell lines. Vet Comp Oncol. 2014 Jun 29. doi: 10.1111/vco. 12100. [Epub ahead of print].

7.  Shin KY, Won BY, Ha HJ, Yun YS, Lee HG. Preclinical safety of the root extract of Polygala tenuifolia Willdenow in Sprague-Dawley rats and beagle dogs. Evid Based Complement Alternat Med. 2014;2014:570134.

8.  Moreau M, Lussier B, Pelletier J, et al. A medicinal herb-based natural health product improves the condition of a canine natural osteoarthritis model: a randomized placebo-controlled trial. Res Vet Sci. 2014;97(3):574–581.

9.  Al-Jenoobi FI, Ahad A, Mahrous G, Al-Mohizea AM, AlKharfy KM, Al-Suwayeh SA. Effects of fenugreek, garden cress, and black seed on theophylline pharmacokinetics in beagle dogs. Pharm Biol. 2015;53(2):296–300.

10. Hanzlicek AS, Roof CJ, Sanderson MW, Grauer GF. The effect of Chinese rhubarb, Rheum officinale, with and without benazepril on the progression of naturally occurring chronic kidney disease in cats. J Vet Intern Med. 2014;28(4):1221–1228.

11. Wang M, Xu X, Xu H, et al. Effect of the total saponins of Aralia elata (Miq) Seem on cardiac contractile function and intracellular calcium cycling regulation. J Ethnopharmacol. 2014;155(1):240–247.

12. Al-Mohizea AM, Ahad A, El-Maghraby GM, Al-Jenoobi FI, AlKharfy KM, Al-Suwayeh SA. Effects of Nigella sativa, Lepidium sativum and Trigonella foenum-graecum on sildenafil disposition in beagle dogs. Eur J Drug Metab Pharmacokinet. 2015;40:219–224.

13. Alkharfy KM, Al-Jenoobi FI, Al-Mohizea AM, Al-Suwayeh SA, Khan RM, Ahmad A. Effects of Lepidium sativum, Nigella sativa and Trigonella foenum-graecum on phenytoin pharmacokinetics in beagle dogs. Phytother Res. 2013;27(12):1800–1804.

14. Al-Mohizea AM, Ahad A, El-Maghraby GM, Al-Jenoobi FI, Al Kharfy KM, Al-Suwayeh SA. Effects of Nigella sativa, Lepidium sativum and Trigonella foenum-graecum on sildenafil disposition in beagle dogs. Eur J Drug Metab Pharmacokinet. 2015;40:219–224.

15. Fukunaga K, Orito K. Time-course effects of St John's wort on the pharmacokinetics of cyclosporine in dogs: interactions between herbal extracts and drugs. J Vet Pharmacol Ther. 2012;35(5):446–451.