Failure of the Animal Model

Issues-Failure-of-the-Animal-ModelThe Issue

The use of animals as stand-ins for humans can give rise to misleading results because of the intrinsic differences between humans and other species. Human disease and human response to drugs and other chemicals should be studied in human-relevant systems.


Animals are used in scientific experimentation based on a presumption that similarities between animals and humans enable data from animal models to be extrapolated to humans. However, the differences between other species and humans make translating data from animals to people problematic.

Advancements in genetics are allowing scientists to appreciate how subtle genetic variations among humans can affect disease risk, progression and response to treatment. How then, can we assume that animals, who by nature are even more different, can accurately predict human response? And even if animals could be predictive, the question arises as to which humans the data could be accurately applied, considering the genetic variability among humans.

Even though humans share genetic material with other animals, it doesn’t necessarily mean it is expressed in the same way. For example, a recent study which compared the activity of human genes important for sepsis, trauma and burns with equivalent mouse genes revealed that humans and mice use very different sets of genes to cope with these insults. This explains why 150 drugs that successfully treated sepsis-like conditions in mice failed in human clinical trials.

Even animals with greater similarity to humans, such as primates, have failed to predict what happens in humans. For example, monkeys treated with a therapeutic antibody (anti-CD28 monoclonal antibody TGN1412) did not predict the potentially fatal immune response that was triggered in humans. The scientific community has also recently concluded that research on chimpanzees, our closest genetic relative, is unnecessary and is being phased out.

There is little consensus among researchers about what the “right” animal model to use is because there is no such thing. Often a model is chosen because it is convenient, inexpensive, easy to handle or has simply been used for a long time, not because it has successfully duplicated what happens in people. Different species—and strains within species for that matter—metabolize drugs and are affected by disease differently. No one model can accurately recapitulate the human condition because animals are not people.

Just because humans have historically relied on animal experiments does not mean we need to continue to do so. Limitations with animal models are encouraging researchers to think outside of the box and develop enhanced research methodologies that focus on humans, not animals.

How NAVS Helps

NAVS advocates for better, more humane and human-relevant science through our financial support of the International Foundation for Ethical Research (IFER). IFER awards grants to scientists at the earliest stages of their careers who are interested in developing alternatives to the use of animals in science. We also recognize the next generation of humane scientists with the NAVS Humane Science Award, presented at the Intel International Science and Engineering Fair.

NAVS also works with scientists in academia, government and industry who are mindful of the inadequacies of animal experiments, who understand the promise of modern technology and who support opportunities to advance smarter science that is human-relevant and can provide safer and more effective solutions to human health needs. We provide positive incentives and support to scientists at all stages of their careers, and partner with international efforts to implement new methodologies that replace the use of animals.

NAVS invests in better, more humane science that promises to pay huge dividends in smarter, better solutions for people and animals. We extend an open invitation and appeal to all scientists and people who care about the advancement of discovery, innovation and scientific knowledge to work together in ways small and grand to capitalize on every opportunity to replace the use of animals with better, more human-relevant alternatives.

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The Failure of the Animal Model