Animal Research

Why do animal research?

Have you ever taken a pill to alleviate pain? Have you received a vaccine against deadly infectious diseases like polio or smallpox? Are you taking medications to lower your blood pressure? Have you had a hip or knee replacement? Do you have a loved one with cancer whose disease is in remission following treatment? If so, then you are the beneficiary of research conducted in animals.

Knowledge based on the study of animals has yielded numerous life-altering and lifesaving treatments—in human and veterinary medicine—including therapies for diabetes, polio, tuberculosis, organ transplantation, hypertension, HIV/AIDS, cardiovascular illness, neurologic disorders, cancer, and COVID-19. Research in animal models has made it possible to contain and treat many serious diseases and even eradicate some, such as smallpox and polio.

Understanding how diseases arise at the molecular level, how they cause dysfunction, and finding ways to combat suffering caused by disease is central to Harvard Medical School’s mission. The humane and regulated study of animals is indispensable for the pursuit of this goal.

Animal research is critical for:

  • Understanding the causes of disease at the very root
    • Animals provide a way to study the fundamental workings of the human body and explore how its basic building blocks—molecules and cells—work in health and disease. In doing so, researchers can unravel the most basic mechanisms that fuel illness.
    • Animal models help researchers understand how the normal processes in molecules, cells, and tissues go awry and give rise to organ dysfunction and, eventually, to full-blown disease.
    • Animal research is invaluable for tackling some of the most confounding human diseases, including neurodegenerative conditions, cancer, metabolic disorders, cardiovascular disease, and emerging infections.
  • Designing and testing new therapies and interventions to improve health
    • Only through understanding the earliest and slightest aberrations in healthy cellular function can scientists design therapies that target the root cause of disease instead of merely alleviating its symptoms.
    • Incorporating animals into research can also help researchers glean insights faster. For instance, the shorter life spans of mice or fruit flies allow researchers to study processes such as those involved in diseases of aging at an accelerated timescale. By comparison, such studies would take decades in humans.
  • Benefiting both animals and humans
    • Animals and people have a lot in common, including physiological pathways of diseases ranging from allergies to cancer to diabetes to neurologic disorders. This means that discoveries in animals can also help design interventions and treatments for pets, animals in the wild, and livestock.
  • Deciphering human biology and physiology
    • Understanding humans starts with understanding animals. For example, mice and humans share nearly the same set of genes, with differences in gene expression varying across regions of the genome.

A privilege, not a right

Members of the Harvard Medical School community understand that using animals in research is a privilege, not a right. Central to the conversation about the use of animals in scientific research are questions such as: Should the public be asked, and is the public willing, to take medicines and use therapies whose safety and efficacy have not been tested in animals? Are these experimental treatments deemed safe enough to test in humans without a safety record from animal testing?

Scientists do not have an automatic right to do animal research but to the extent that we, as a society, want to save human lives and alleviate suffering caused by disease, we have to accept that some advances are impossible without animal research.

Richard Born

Professor of neurobiology, HMS

“Scientists do not have an automatic right to do animal research but to the extent that we, as a society, want to save human lives and alleviate suffering caused by disease, we have to accept that some advances are impossible without animal research,” says Richard Born, professor of neurobiology at Harvard Medical School, whose work focuses on understanding vision through the study of structures and processes in areas of the brain that enable us to see.

Scientists continue to refine their methods of research to ensure that they avoid the use of animals when possible and that, when animals must be used, the number of animals involved is as small as possible. However, these non-animal alternatives have limitations and cannot yet fully replace animal research. As these non-animal alternatives evolve, scientists continue to adhere to current legal requirements and ethical guidelines that define when animal research must be done before therapies and treatments can be tested in humans.

About 95 percent of animal research in the United States involves rodents, according to the National Association for Biomedical Research.

Our faculty and staff are continually refining how they study and care for animals in our labs, striving to reduce the number of animals used in research, and using nonanimal models whenever possible.

Alternative techniques such as studying cells in lab dishes, using organs on a chip, or using computer models to explore interactions have their applications in research and offer some advantages. Despite recent advances, however, these technologies can’t yet replace animals fully — in part because it is critical to study biological processes in a complex system.

A single cell in a dish does not behave in the same way it does when it’s connected to other cells, when it’s a part of an organ system such as the heart or the liver or the brain, or when it’s embedded in the even more complex environment of a body. For instance, drug metabolism — how chemicals are processed and broken down by the body and whether they have any harmful effects on various organs — cannot be studied outside of the whole body. As biotechnologies evolve, it’s possible that researchers in the future will need to use animals less and less.

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