Homeopathic treatment of weaned piglets

Sir,

Soto et al.'s[ ¹ ] paper in Homeopathy's October 2008 issue concludes that giving newborn piglets homeopathic supplements could reduce their postnatal diarrhoea-induced weight loss. It describes a trial comparing a control group of piglets fed no sucrose saline to 24 piglets fed with plain sucrose saline and 24 other piglets fed with sucrose saline and a homeopathic complex. Analyses of the piglets' subsequent weight loss revealed that the piglets fed homeopathically treated sucrose lost less weight than the other piglets; this difference was statistically significant.

Soto et al. suggest that this result was an effect of the homeopathy. Examining their results more closely, however, indicates a more likely explanation: baseline differences in the piglets' weights.

The homeopathy group piglets weighed about 400 g less than the other piglets before the trial began. Soto et al. mention this, and also point out (correctly) that this difference was statistically insignificant. Soto et al. do not mention that the initial weights of the homeopathy group piglets also had less variance than those of the other piglets: the homeopathy group piglets' original weights had a standard deviation of 0.69 kg, as compared to 1.08 kg in both the other groups. These differ significantly (F = 2.45, p = 0.036). This suggests that the homeopathy group piglets' initial weights came from a different statistical population to the control piglets' weights, and that an assumption of the analyses of variance and Tukey tests that Soto et al. performed – namely, homogeneity of variance – was violated.

It is also significant that the homeopathy group piglets lost less weight than the other piglets despite eating no more than them and suffering as much diarrhoea. This result in particular is hard to reconcile with the hypothesis that the homeopathy group piglets lost less weight because the homeopathy stanched their diarrhoea.

If, as these facts imply, Soto et al.'s positive results are due merely to pre-trial differences, their view that “[t]hese data suggest that the supplementation…with added homeopathic medicine…may be an useful option to reduce weight loss in weaned piglets” is difficult to sustain.

Soto et al. have declined to respond.

• Reference

• 1 Soto F.R.M., Vuaden E.R., Coelho C.dP., Benites NR., Bonamin LV., de Azevedo SS. A randomized controlled trial of homeopathic treatment of weaned piglets in a commercial swine herd. Homeopathy 2008; 97: 202-205.