Alternative Methods

Limitations

All research methods and techniques have limitations, regardless of whether they use non-human animals or not. 

Firstly, there are ethical concerns. Non-human animals suffer in experiments. At a minimum, they suffer due to confinement but most often from invasive procedures. It is morally wrong to inflict harm on non-human sentient beings.  

Ethical issues with human subjects are less pervasive but may occur. E.g. in the lack of genuine informed consent, and the use of embryonic stem cells. (Stem cells from liver and skin are now available.)  

In vitro and in silico studies may not give information about complex interactions of living systems. As virtual humans become more sophisticated this weakness should be overcome. 

The British Medial Journal lists the following methodological problems of animal experiments:

• Disparate animal species and strains, with a variety of metabolic pathways and drug metabolites, leading to variation in efficacy and toxicity

• Different models for inducing illness or injury with varying similarity to the human condition

• Variations in drug dosing schedules and regimen that are of uncertain relevance to the human condition

• Variability in the way animals are selected for study, methods of randomisation, choice of comparison therapy (none, placebo, vehicle), and reporting of loss to follow up

• Small experimental groups with inadequate power, simplistic statistical analysis that does not account for potential confounding, and failure to follow intention to treat principles

• Nuances in laboratory technique that may influence results may be neither recognised nor reported - eg methods for blinding investigators

• Selection of a variety of outcome measures, which may be disease surrogates or precursors and which are of uncertain relevance to the human clinical condition

• Length of follow up before determination of disease outcome varies and may not correspond to disease latency in humans

Pound, P., Ebrahim, S., Sandercock, P., Bracken, M., and Roberts, I. 2004, Where is the evidence that animal research benefits humans? BMJ, 328: 514-517.