In recent years, the landscape of scientific research involving animals is undergoing a profound transformation. Governments around the world are announcing ambitious plans to significantly reduce, and eventually eliminate, the use of animals in experimental procedures. This shift is driven by growing ethical concerns about animal welfare and remarkable advances in alternative scientific methods that promise to replace animal testing. Yet, despite the optimism surrounding these new approaches, substantial challenges remain before animal experiments can be fully phased out.
One of the most notable policy announcements came from the United Kingdom in November 2025. The UK government unveiled a bold strategy to phase out animal testing in various areas of research, setting concrete targets such as eliminating animal tests for skin irritation by 2026 and reducing studies involving dogs by 2030. Their ultimate goal is a future “where the use of animals in science is eliminated in all but exceptional circumstances.” Similar commitments have been echoed internationally: the US Food and Drug Administration (FDA) plans to make animal studies the exception rather than the norm in drug safety and toxicity testing within the next three to five years, while the US National Institutes of Health (NIH) has launched initiatives to reduce animal use in research funding. Meanwhile, the European Commission intends to publish a roadmap to end animal testing in chemical safety assessments.
These policy shifts are fueled not only by ethical and animal welfare considerations but also by rapid progress in ‘new approach methodologies’ (NAMs). NAMs comprise innovative technologies such as organs-on-chips, 3D tissue cultures known as organoids, and sophisticated computational models powered by artificial intelligence. These models often utilize human cells or data to better mimic human biology, offering potentially more accurate predictions of drug safety and efficacy compared to traditional animal models. For example, organs-on-chips are microfluidic devices that replicate key functions of human organs, enabling researchers to study disease processes and drug effects in a controlled environment. Similarly, organoids are miniature, lab-grown versions of human tissues that capture many features of real organs, providing an invaluable platform for disease modeling and drug screening.
The scientific literature reflects this surge in NAMs, with the number of biomedical publications relying solely on these methods increasing fourfold from about 25,000 in 2006 to 100,000 by 2022, according to Animal Free Research UK. Furthermore, countries like China are investing heavily in this field, with a 2024 infrastructure project—the Human Organ Physiopathology Emulation System—supported by a $382 million investment to advance NAMs development.
Proponents of NAMs argue that these technologies can outperform animal models in predicting human responses because they are based on human biology. Donald Ingber, a bioengineer at the Wyss Institute and co-founder of Emulate—a company specializing in organs-on-chips—describes the shift towards alternatives as “long overdue.” However, he cautions that many NAMs are still under development and require rigorous validation before they can fully replace animal studies. Some biological systems are inherently complex and unpredictable, and current models cannot yet replicate all aspects of human physiology.
Efforts to reduce animal use in science have been ongoing for decades, following the principles of the 3Rs: Replacement, Reduction, and Refinement. These efforts have yielded measurable decreases in animal testing in some regions. For instance, the UK saw a drop in scientific procedures on animals from 4.14 million in 2015 to 2.64 million in 2024. Similarly, the European Union and Norway reported a 5% reduction in animal use between 2018 and 2022. However, in the United States, tracking is more difficult because reporting laws exclude rats, mice, and fish—the most commonly used species.
Mice and rats constitute approximately 67% of animal testing in the UK, with the majority of procedures (76%) dedicated to basic and applied research such as understanding disease mechanisms and developing therapies. Another 22% of animal experiments focus on regulatory testing, including toxicity and safety assessments of new drugs and chemicals. Despite their widespread use, animal models have significant limitations. Drugs that show promise in preclinical animal tests frequently fail in human clinical trials—about 86% of investigational drugs do not succeed. This high failure rate is partly due to species differences; for example, the immune systems of rodents differ markedly from humans, making it challenging to model complex diseases like sepsis accurately in mice.
NAMs offer promising solutions to these challenges. Joseph Wu, a cardiologist and researcher at Stanford University