Your Annual Reminder that there is no Reason to Believe Homeopathy Can Help Your Pet

I have devoted far too much time and energy to the least plausible of alternative therapies in veterinary medicine, homeopathy. From a comprehensive literature review in 2012 to a detailed response to the best evidence the Academy of Veterinary Homeopathy could muster, and much more, I have done my best to make sure pet owners don’t get taken in by the baseless claims for this bogus practice. I know, of course, that such efforts will never be complete, but over the years, I’ve rather lost interest in the subject. There are only so many ways to say, “It doesn’t work,” and the evidence isn’t likely to change without the complete upending of centuries of established science.

That said, every once in a great while, I feel the need to remind everyone that, nope, homeopathy still doesn’t work. Earlier this year, yet another systematic review of the veterinary homeopathy literature was published:

Bez, I. C. C., Paula, G. Z. de, Revers, N. B. M., Oliveira, A. C. da F. de, Weber, S. H., Sotomaior, C. S., & Costa, L. B. (2024). The use of homeopathy in veterinary medicine: a systematic review. Semina: Ciências Agrárias, 45(3), 783–798.

Goodness knows, we don’t need more studies or more reviews to serve as a few more nails in the coffin of this idea, but hope and delusion spring eternal in the human psyche, so here we are. Despite the lack of a plausible reason for conducting it, and the almost certain pro-homeopathy bias of researchers still looking under rocks for evidence that it does something, the review followed pretty standard guidelines and practices for systematic reviews. The results?

• 161 studies found
• 8 studies that met the minimum criteria for analysis
• 3 studies that were consider to have a low risk of bias

Of these, one was in cows, one in cats, and one in dogs. The cow and cat studies found no effect. The dog study did report a positive outcome.

Raj PAA, Pavulraj S, Kumar MA, Sangeetha S, Shanmugapriya R, Sabithabanu S. Therapeutic evaluation of homeopathic treatment for canine oral papillomatosis. Vet World. 2020 Jan;13(1):206-213.

This was a small study, involving 16 dogs, and it was conducted in India, where homeopathy is more widely used and believed to be effective than in other parts of the world. The condition was viral papilloma, an infectious wart that typically goes away without treatment within 4-8 weeks. According to the paper, the dogs were randomly assigned to homeopathy (8, a mixture of remedies at the 30C dilution, which means no trace of the original ingredient could possibly remain) or placebo (8, distilled water).

The reported results are quite dramatic. All of the dogs given the homeopathic remedy were “cured” by less than three weeks, while many of the dogs given placebo still had lesions up to 5 months (20 weeks).

This certainly looks like compelling evidence. You will not be surprised, however, to hear I am not convinced. If hundreds of studies are done by people committed to proving what they already believe, some will appear to succeed even with reasonable attempts to eliminate bias. We have already seen this in previous studies of homeopathy. A famous study published in the prestigious journal Nature in 1988 appeared to show incontrovertible proof of biological effects of highly dilute homeopathic remedies in vitro. Subsequent investigation found the results could not be repeated if the investigators were effectively blinded, as they ought to have been in the first place.

There are a number of red flags in this paper. The persistence of lesions much longer than normal in the placebo group raises questions about the original diagnosis and whether these were normal papillomas in normal dogs. Did the treatment group resolve much faster because of the remedy, or could there have been some hidden bias in how the dogs were selected, treated, or evaluated?

I certainly don’t have an explanation for the results, but given the consistent failure of homeopathy in scientific investigations for many decades, the explanation that homeopathy cured these dogs is not the most likely. Replication of these results in other studies by different, independent investigators would be needed to even begin to suggest that as a realistic possibility, and more likely explanations, such as residual bias or error, would have to be eliminated.

Thus does the zombie of homeopathy lurch along, sustained by the desperate proliferation of numerous studies, most methodologically poor, and the occasional apparent success which mysteriously, is never replicated or proven to be true.