"We must keep an open mind!" is a cry frequently heard from veterinary surgeons who have little familiarity with homoeopathy, and whose main concern seems to be to avoid offending anyone. This is usually followed by the assertion, "We need more research!"
An open mind is an admirable approach to a new idea. However, it is possible to have such an open mind that your brain falls out. Homoeopathy has been around for a good two hundred years - the first publication was in 1796. Are we really still short of the information we need to start coming to some conclusions?
Before calling for even more research spending, why not take a look at what's already out there? There are also review articles and 'meta-analyses' which attempt to draw all the information together and provide an overview. Yet more articles have summarised the review articles (for example Prescrire International, 1996; Wagner, 1997; Ramey, 2000; Barrett, 2002; Ernst, 2002). See also the relevant Bandolier section. Many of these present the situation as very disappointing for homoeopathy, with only a few marginally positive findings which on examination don't really amount to a hill of beans. Indeed there is at least one homoeopathy proponent paper which admits exactly the same thing (Walach, 2000). On the other hand, pro-homoeopathic glosses can be found which, simply by quoting different excerpts from the very same papers, present the discipline as being strongly backed up by an extensive body of reputable research (for example Hoare, 2003).
The most truthful assessment of 200 years of research is perhaps that it has signally failed to persuade the doubters to believe, but it has equally failed to persuade the believers to doubt. A few points are indisputable, however.
One area where reproducibility has been claimed is in the work of David Reilly's group at the Glasgow Homoeopathic Hospital (Reilly et al., 1994; Taylor et al., 2000), though this approach to the treatment of hay fever is in fact isopathy rather than homoeopathy, and lacks classical homoeopathic individualisation. However, the claimed reproducibility is only within the original research group, and the statistical analyses employed have been subjected to much criticism. More recently another group at Exeter University met the common objection that much of the controlled trial work in homoeopathy is not individualised, by allowing normal individualisation in the treatment of childhood asthma (White et al., 2003). The conclusion of this much more rigorous trial was that there was no difference between the homoeopathic treatment and a placebo. (Noted without comment: about three weeks after the White et al. paper was published, the government announced the allocation of £1.3 million for research into complementary medicine, principally homoeopathy. Prince Charles was reportedly delighted.)
It's quite difficult to keep up with the growing literature in this area. Even the review articles and meta-analyses, summarised on a separate page for reference, present a moving target. Fifteen years of review and meta-analysis. After a first starkly negative conclusion in 1990, the 1990s were characterised by reviews that seemed to delight in the frisson of mystery invoked by the suggestion that maybe, just maybe, there could be something there. However, since the turn of the millennium, more rigorous scrutiny has generally prevailed, and the possibility that maybe, just maybe, some homoeopathy proponents might have been over-playing their hand has been recognised. The most recent article again comes firmly down on the "no effect beyond placebo" side of the fence, prompting a very testy editorial in the Lancet criticising the "politically-correct" tolerance of homoeopathy in the medical profession, and the wasting of yet more research funds in investigating "selective analyses and biassed reports". The editor calls on doctors to be "bold and honest with their patients about homoeopathy’s lack of benefit". Watch this space.
When considering specifically veterinary trials, results are even more disappointing than in man, with no controlled studies of any degree of credibility having demonstrated a significant effect. In one memorable paper Taylor et al. (1989) described seven calves treated with a commercially purchased homoeopathic nosode for Dictyocaulus viviparus and seven with a sham solution, both groups then being challenged with virulent larvae. No antibody could be demonstrated in either group, mortality in both groups was high, and there was no difference in the number or morphology of the worms recovered from the groups post mortem. The conclusion was that "There were no discernable differences between the treated and the control groups in their manifestations of resistance to D. viviparus or their clinical responses to the diseases produced." Proponent reaction was to reassert that homoeopathy works in clinical situations, and to deplore the condemnation of its use on the basis of a single unsuccessful experiment (MacLeod, 1989; Webb, 1989; Couzens, 1989).
More recently, other authors have reported similar findings. Scott et al. (2002) studied a commercial homoeopathic remedy for dermatitis in 18 dogs suffering from atopic dermatitis. One dog in each group (treated and control) showed a reduction in pruritus (to less than 50% of pre-treatment severity) after treatment. This study also generated much criticism from homoeopathy proponents, mainly on the grounds that as the treatment had not been administered by homoeopaths, the results were therefore invalid. The fact that the remedy used, like the nosode employed by Taylor et al. (1989), had been purchased from a commercial source advertising it as suitable for exactly that purpose, was not commented on by the critics. The following year de Verdier et al. (2003) treated 24 calves suffering from neonatal diarrhoea with a D30 preparation of Podophyllum, and compared them to a group of 20 similar calves given a sham solution, in a double-blind study. There was no significant difference between the groups with respect to depression, inappetance and fever, and the treated group actually had a slightly longer duration of diarrhoea than the control group. In the light of these findings, the authors expressed concern about the welfare implications of the fact that homoeopathic treatment is encouraged among "organic" farmers in the EU. Once again, the study was dismissed by homoeopaths on the grounds of lack of individualisation, ignoring the fact that this is exactly how homoeopathy is actually practised in farm animal medicine.
Since this page was written, a fourth controlled trial of veterinary homoeopathy has been published (Holmes et al., 2005). Once again the trial involved a commercially-marketed product, in this case a "mastitis nosode", marketed by a homoeopathic pharmacy with impressive therapeutic claims. No information was available regarding what was (or wasn't!) contained in this "broad-spectrum treatment régime", although the authors imply that it was not necessarily diluted beyond Avogadro's limit. Nevertheless, "Within the limits of the power of this trial there was no evidence to show that the homoeopathic nosode tested had any effect on the cows’ somatic cell counts."
Oops, just noticed another recent one, Hektoen et al., (2004). Mastitis again, but this time the clinical disease. "Evidence of efficacy of homeopathic treatment beyond placebo was not found in this study," what a surprise.
To the best of our knowledge, these
four five studies are the only controlled trials of homoeopathic treatment in veterinary medicine which have achieved publication in reputable journals.
As long ago as 1842, after describing a number of trials in which homoeopathic remedies had been found to be completely worthless, Oliver Wendell Holmes observed -
It is impossible not to realize the entire futility of attempting to silence this asserted science by the flattest and most peremptory results of experiment. Were all the hospital physicians of Europe and America to devote themselves, for the requisite period, to this sole pursuit, and were their results to be unanimous as to the total worthlessness of the whole system in practice, this slippery delusion would slide through their fingers without the slightest discomposure, when, as they supposed, they had crushed every joint in its tortuous and trailing body.
Not much change there, then.
Proponents of homoeopathy frequently cite extremely dramatic individual anecdotes in support of their claims (for example Nunn, 1984; Hunter, 1991; Mueller, 2003). If such striking effects are typical of homoeopathic preparations, or in any way reproducible, it should be easy to demonstrate this even to the most sceptical of critics. However, we seem to have little to show for a considerable amount of effort but marginal and inconsistent significances in small or poorly-controlled trials.
Continuing to pursue a line of investigation in the face of disappointing or inconclusive results usually depends on a conviction that the underlying theory is sound, and that it is rational to expect a positive result if the studies are better designed or the procedure is refined. Does the underlying theory of homoeopathy lend itself to such a rational scientific belief?
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BARRETT, S. (2002) Overview of homeopathic research. HomeoWatch, www.homeowatch.org/research/overview.html.
COUZENS, T. W. (1989) Homoeopathy. Vet. Rec. 124, 355.
ERNST, E. (2002) A systematic review of systematic reviews of homeopathy. Br. J. Clin. Pharmacol. 54, 577-582.
HEKTOEN, L., LARSEN, S., ØDEGAARD, S. A. & LØKEN, T. (2004) Comparison of Homeopathy, Placebo and Antibiotic Treatment of Clinical Mastitis in Dairy Cows – Methodological Issues and Results from a Randomized-clinical Trial. J. Vet. Med. 51, 439-446.
HOARE, J. (2003) In defence of homoeopathy. Veterinary Times 33:15, 7.
HOLMES, M. A., COCKCROFT, P. D., BOOTH, C. E. & HEATH, M. F. (2005) Controlled clinical trial of the effect of a homoeopathic nosode on the somatic cell counts in the milk of clinically normal dairy cows. Vet. Rec. 156, 565-567.
HOLMES, O. W. (1842) Homeopathy and its kindred delusions. In Examining Holistic Medicine, ed. D. Stalker & C. Glymour, 1985. New York: Prometheous Books.
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MACLEOD, G. (1989) Homoeopathy. Vet. Rec. 124, 355.
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NUNN, R. J. (1984) Homoeopathic treatment of partial epilepsy. Vet. Rec. 114, 24.
PRESCRIRE INTERNATIONAL (unattributed articles) (1996) Homeopathy update. Prescrire International, 5:21.
RAMEY, D. W. (2000) The scientific evidence on homoeopathy. Priorities for Health 12, 19-21, 40.
REILLY, D., TAYLOR, M. A., BEATTIE, N. G., CAMPBELL, J. H., McSHARRY, C., AITCHISON, T. C., CARTER, R. & STEVENSON, R. D. (1994) Is evidence for homeopathy reproducible? Lancet, 344, 1601-1606.
SCOTT, D. W., MILLER, W. H. Jr., SENTER, D. A. et al. (2002) Treatment of canine atopic dermatitis with a commercial homeopathic remedy: A single-blinded, placebo-controlled study. Can. Vet. J. 43, 601-603.
TAYLOR, M. A., REILLY, D., LLEWELLYN-JONES, R. H., McSHARRY, C. & AITCHISON, T. C. (2000) Randomised controlled trial of homoeopathy versus placebo in perennial allergic rhinitis with overview of four trial series. British Medical Journal 321, 471-476.
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de VERDIER, K., ÖHAGEN, P. & ALENIUS, S. (2003) No effect of a homeopathic preparation on neonatal calf diarrhoea in a randomised double-blind, placebo-controlled clinical trial. Acta Vet. Scand. 44, 97-101.
WAGNER, M. W. (1997) Is Homeopathy 'New Science' or 'New Age'? Scientific Review of Alternative Medicine 1, 7-12.
WALACH, H. (2000) Magic of signs: a non-local interpretation of homeopathy. Br. Hom. J. 89, 127-140.
WEBB, A. H. (1989) Homoeopathy. Vet. Rec. 124, 355.
WHITE, A., SLADE, P., HUNT, C., HART, A. & ERNST, E. (2003) Individualised homeopathy as an adjunct in the treatment of childhood asthma: a randomised placebo controlled trial. Thorax 58, 317-321.