Randomised controlled trials of veterinary homeopathy: characterising the peer-reviewed research literature for systematic review

[Naturopathy and complementary medicine in small animal science - definitions and contents]

Naturopathic and complementary procedures attain increasing popularity in veterinary medicine. A common understanding of definitions and contents of these fields is crucial for communication between pet owners and veterinarians. This paper reviews the existing definitions and the various contents of naturopathy and complementary veterinary medicine as well as their assigned treatment options. Naturopathy includes phytotherapy, hydro-therapy, thermotherapy, electrotherapy, manual therapy/chiropractic/osteopathy, and dietetic treatment. Homeopathy, homotoxicology, Traditional Chinese Medicine including acu-puncture and Chinese herbal medicine, neural therapy, organotherapy and Bach flower remedies are known as complementary treatments. The level of evidence based on scientific literature and the opportunity for certification procedures differ between treatment modalities. In the area of small animal medicine, the most extensive body of literature is available on the subject of acupuncture, in part comprising high evidence levels.

Comparison of veterinary drugs and veterinary homeopathy: part 2

Part 2 of this narrative review outlines the theoretical and practical bases for assessing the efficacy and effectiveness of conventional medicines and homeopathic products. Known and postulated mechanisms of action are critically reviewed. The evidence for clinical efficacy of products in both categories, in the form of practitioner experience, meta-analysis and systematic reviews of clinical trial results, is discussed. The review also addresses problems and pitfalls in assessing data, and the ethical and negative aspects of pharmacology and homeopathy in veterinary medicine.

Comparison of veterinary drugs and veterinary homeopathy: part 1

For many years after its invention around 1796, homeopathy was widely used in people and later in animals. Over the intervening period (1796-2016) pharmacology emerged as a science from Materia Medica (medicinal materials) to become the mainstay of veterinary therapeutics. There remains today a much smaller, but significant, use of homeopathy by veterinary surgeons. Homeopathic products are sometimes administered when conventional drug therapies have not succeeded, but are also used as alternatives to scientifically based therapies and licensed products. The principles underlying the veterinary use of drug-based and homeopathic products are polar opposites; this provides the basis for comparison between them. This two-part review compares and contrasts the two treatment forms in respect of history, constituents, methods of preparation, known or postulated mechanisms underlying responses, the legal basis for use and scientific credibility in the 21st century. Part 1 begins with a consideration of why therapeutic products actually work or appear to do so.

Efficacy of homeopathy in livestock according to peer-reviewed publications from 1981 to 2014

Homeopathy is widely used in livestock, especially in order to reduce the use of antibiotics, although it is often seen as controversial. A comprehensive literature review has been conducted to assess the efficacy of homeopathy in cattle, pigs and poultry. Only peer-reviewed publications dealing with homeopathic remedies, which could possibly replace or prevent the use of antibiotics in the case of infective diseases or growth promotion in livestock were included. Search results revealed a total number of 52 trials performed within 48 publications fulfilling the predefined criteria. Twenty-eight trials were in favour of homeopathy, with 26 trials showing a significantly higher efficacy in comparison to a control group, whereas 22 showed no medicinal effect. Cure rates for the treatments with antibiotics, homeopathy or placebo varied to a high degree, while the remedy used did not seem to make a big difference. Looking at all the studies, no study was repeated under comparable conditions. Consequently, the use of homeopathy currently cannot claim to have sufficient prognostic validity where efficacy is concerned. When striving for high therapeutic success in treatment, the potential of homeopathy in replacing or reducing antibiotics can only be validated if evidence of efficacy is confirmed by randomised controlled trials under modified conditions.

Veterinary homeopathy: systematic review of medical conditions studied by randomised trials controlled by other than placebo

Background

No systematic review has previously been carried out on randomised controlled trials (RCTs) of veterinary homeopathy in which the control group was an intervention other than placebo (OTP). For eligible peer-reviewed RCTs, the objectives of this study were to assess the risk of bias (RoB) and to quantify the effect size of homeopathic intervention compared with an active comparator or with no treatment.

Methods

Our systematic review approach complied fully with the PRISMA 2009 Checklist. Cochrane methods were applied to assess RoB and to derive effect size using standard meta-analysis methods. Based on a thorough and systematic literature search, the following key attributes of the published research were distinguished: individualised homeopathy (n = 1 RCT)/non-individualised homeopathy (n = 19); treatment (n = 14)/prophylaxis (n = 6); active controls (n = 18)/untreated controls (n = 2). The trials were highly diverse, representing 12 different medical conditions in 6 different species.

Results

No trial had sufficiently low RoB to be judged as reliable evidence: 16 of the 20 RCTs had high RoB; the remaining four had uncertain RoB in several domains of assessment. For three trials with uncertain RoB and without overt vested interest, it was inconclusive whether homeopathy combined with conventional intervention was more or was less effective than conventional intervention alone for modulation of immune response in calves, or in the prophylaxis of cattle tick or of diarrhoea in piglets.

Conclusion

Due to the poor reliability of their data, OTP-controlled trials do not currently provide useful insight into the effectiveness of homeopathy in animals.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0542-2) contains supplementary material, which is available to authorized users.

Veterinary homeopathy: meta-analysis of randomised placebo-controlled trials

BACKGROUND

Meta-analysis of randomised controlled trials (RCTs) of veterinary homeopathy has not previously been undertaken. For all medical conditions and species collectively, we tested the hypothesis that the outcome of homeopathic intervention (treatment and/or prophylaxis, individualised and/or non-individualised) is distinguishable from corresponding intervention using placebos.

METHODS

All facets of the review, including literature search strategy, study eligibility, data extraction and assessment of risk of bias, were described in an earlier paper. A trial was judged to comprise reliable evidence if its risk of bias was low or was unclear in specific domains of assessment. Effect size was reported as odds ratio (OR). A trial was judged free of vested interest if it was not funded by a homeopathic pharmacy. Meta-analysis was conducted using the random-effects model, with hypothesis-driven sensitivity analysis based on risk of bias.

RESULTS

Nine of 15 trials with extractable data displayed high risk of bias; low or unclear risk of bias was attributed to each of the remaining six trials, only two of which comprised reliable evidence without overt vested interest. For all N = 15 trials, pooled OR = 1.69 [95% confidence interval (CI), 1.12 to 2.56]; P = 0.01. For the N = 2 trials with suitably reliable evidence, pooled OR = 2.62 [95% CI, 1.13 to 6.05]; P = 0.02).

CONCLUSIONS

Meta-analysis provides some very limited evidence that clinical intervention in animals using homeopathic medicines is distinguishable from corresponding intervention using placebos. The low number and quality of the trials hinders a more decisive conclusion.

Veterinary clinical research database for homeopathy: placebo-controlled trials

BACKGROUND

Veterinary homeopathy has led a somewhat shadowy existence since its first introduction. Only in the last three decades has the number of clinical trials increased considerably. This literature is generally not well perceived, which may be partly a consequence of the diffuse and somewhat inaccessible nature of some of the relevant research publications. The Veterinary Clinical Research Database for Homeopathy (VetCR) was launched in 2006 to provide information on existing clinical research in veterinary homeopathy and to facilitate the preparation of systematic reviews.

OBJECTIVE

The aim of the present report is to provide an overview of this first database on clinical research in veterinary homeopathy, with a special focus on its content of placebo controlled clinical trials and summarising what is known about placebo effects in animals.

RESULTS

In April 2012, the VetCR database contained 302 data records. Among these, 203 controlled trials were identified: 146 randomised and 57 non-randomised. In 97 of those 203 trials, the homeopathic medical intervention was compared to placebo.

COMMENT

A program of formal systematic reviews of peer-reviewed randomised controlled trials in veterinary homeopathy is now underway; detailed findings from the program's data extraction and appraisal approach, including the assessment of trial quality (risk of bias), will be reported in due course.