More studies needed to explore effects of complementary therapies in animals – review

Leeches are used in Medical Leech Therapy (MLT) or hirudotherapy. Image by István Asztalos
Medical Leech Therapy (MLT) or hirudotherapy was one of the complementary and alternative veterinary medicines reviewed. Image by István Asztalos

A lack of scientific studies on complementary and alternative therapies used in animals has been identified in a just-published review.

Complementary and alternative veterinary medicine describes a range of therapies that vary in theory and practice. They are commonly used in animals, and mainly delivered by therapists without a veterinary medical background.

Anna Bergh and her fellow researchers, writing in the journal Animals, noted that there is an increasing interest in such therapies. However, there is limited knowledge of how they affect animals.

The researchers set out to review the scientific literature on 24 different complementary and alternative therapies used in horses, cats and dogs.

They systematically checked three online databases for relevant articles, which were assessed for scientific quality. Information was extracted on study characteristics, species, type of treatment, indication, and treatment effects.

Of 982 unique publications screened, 42 were assessed as eligible for inclusion, representing nine different therapies — aromatherapy, gold therapy, homeopathy, leeches (hirudotherapy), mesotherapy, mud, neural therapy, sound (music) therapy, and vibration therapy. For the other 15 predefined therapies, no study was identified.

The risk of bias was assessed as high in 17 studies, moderate to high in 10, moderate in 10, low to moderate in four, and low in one study.

However, in those studies where the risk of bias was low to moderate, there was considerable variability in reported treatment effects.

“Therefore, the scientific evidence is not strong enough to define the clinical efficacy of the 24 complementary and alternative veterinary medicine therapies,” the review team concluded.

The authors said their work revealed significant gaps in scientific knowledge regarding the effects of a number of methods used in horses, cats and dogs.

“For the majority of the therapies, no relevant scientific articles were retrieved. For nine therapies, some research documentation was available. However, due to small sample sizes, a lack of control groups, and other methodological limitations, few articles with a low risk of bias were identified.”

Where beneficial results were reported, they were not replicated in other independent studies.

“Many of the articles were in the lower levels of the evidence pyramid, emphasising the need for more high-quality research using precise methodologies to evaluate the potential therapeutic effects of these therapies,” they said.

Of the publications that met inclusion criteria, most did not have scientific documentation of sufficient quality to draw any conclusion regarding their effect.

Several of their observations may be translated into lessons on how to improve the scientific support for such therapies, they said. Crucial efforts include:

  • A focus on the evaluation of therapies with an explanatory model for a mechanism of action accepted by the scientific community at large;
  • The use of appropriate control animals and treatments, preferably in randomized controlled trials;
  • High-quality observational studies with emphasis on control for confounding factors;
  • Sufficient statistical power. To achieve this, large-scale multicenter trials may be needed;
  • The inclusion of blinded evaluations; and
  • Replication studies of therapies that have shown promising results in single studies.

The review team comprised Bergh, with the Department of Clinical Sciences at the Swedish University of Agricultural Sciences; Iréne Lund, with the Department of Physiology and Pharmacolgy at the Karolinska Institute in Stockholm; Anna Boström and Heli Hyytiäinen, with the Department of Equine and Small Animal Medicine at the University of Helsinki; and Kjell Asplund, with the Department of Public Health and Clinical Medicine at Umeå University in Sweden.

Bergh, A.; Lund, I.; Boström, A.; Hyytiäinen, H.; Asplund, K. A Systematic Review of Complementary and Alternative Veterinary Medicine: “Miscellaneous Therapies”. Animals 2021, 11, 3356.

The study, published under a Creative Commons License, can be read here

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