Why Animal Research Is Necessary

Even though scientists are continually trying to minimize the use of animals and to replace them with non-animal alternatives, animal research remains critical and necessary to comply with legal requirements, for ethical and safety reasons, and to address other scientific and practical considerations.

Legal requirements

In an effort to reduce the use of animals in clinical research, in December 2022 the U.S. government passed legislation that allows drug manufacturers to submit testing data based on non-animal alternatives for biosimilar drugs — medicines that are highly similar to other, already approved ones. However, for safety and efficacy reasons, the U.S. Food and Drug Administration continues to require that investigational new drugs be first tested in animal models before using them in humans.

The ethics of research in humans

While some treatments and procedures can be studied in humans without using animal models first, many therapies require testing in animals before being used in humans. In the wake of historical atrocities involving experimentation in humans, the international community has established ethical guidelines that call for conducting animal studies before experiments can progress to trials in humans.

Scientific and practical considerations

• To understand how a given disease arises at the most basic level and how it progresses through various stages, researchers must induce the disease in animal models—something that would be neither ethical nor possible to do in humans.
• Certain experiments are simply impossible in humans. For example, researchers who study the gut microbiome must often feed different groups of animals strictly controlled diets. They must keep them in an entirely sterile environment free of any germs or engineer them to have guts completely free of any microbes. None of this is possible in humans.
• For some types of research, animals must be engineered to have or lack certain genes (or the proteins made by these genes) in order to determine what role a gene and its protein might play in disease development. This is not possible to do in humans for legal, ethical, and scientific reasons.
• Researchers often recreate many serious diseases — including cancer, neurodegenerative conditions, and autoimmune diseases — in animal models to study a condition in detail and to test possible treatments. Doing so in humans would not be ethical, legal, or possible.