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Why do critics question whether animal models are always necessary for medical research?

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Three PETA protesters in animal masks and green clothing hold signs reading No Fur at a demonstration against fur in clothing at a shopping district in Seoul, South Korea. — Animal rights A PETA (People for the Ethical Treatment of Animals) demonstration in Seoul, South Korea, against the use of animals for fur in clothing.

Critics question the necessity of animal models in medical research primarily due to ethical concerns and doubts regarding the scientific reliability of these models for human outcomes.1

Ethical Concerns

A central moral issue is whether it is justifiable to subject sentient beings to pain, suffering, or death for human benefit. Because animals cannot provide consent, critics argue they deserve protection from harm. This perspective emphasizes that animals are sentient and that their welfare should be prioritized over experimental utility.1

Scientific Reliability and Alternatives

Critics also challenge the effectiveness of animal testing, noting that a high percentage of drugs that succeed in animal trials fail during human clinical trials. They point to instances where animal tests failed to predict human reactions—such as the case of thalidomide—or misled researchers into abandoning potentially effective treatments.2

Furthermore, opponents argue that modern alternatives can often replace animal use. These include:13
* In vitro testing: Using human cells or tissues in laboratory settings.3
* Advanced modeling: Utilizing computer simulations and organ-on-a-chip technology to mimic human biological functions.1
* Human studies: Relying on volunteer participants who can provide informed consent.13

These arguments support the "three Rs" principle: replacement, reduction, and refinement.1