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Frequently Asked Questions About Medical Research

Q: How many (nonhuman) animals are used in research each year?

It is impossible to precisely state how many animals are used globally for research. Only 37 countries publish national statistics, and the definitions of “research” and “animal” both vary domestically and abroad.

And although researchers try to standardize the definition of “animal” when compiling data, it’s not always possible to compare data sets between countries—or even between US research facilities.

Using reports from the 37 reporting countries, and additional prediction modeling, experts estimate that roughly 192.1 million animals were used for scientific purposes worldwide in 2015.

Based on the increase in the numbers of animals used in research from 2005 to 2015, it is likely that that the number of animals used in research each year continues to grow.



Q: Which species of animals are used in medical research?

In the US, almost any species of animal can be used in research.

In 2015, after decades of invasive chimpanzee research, the US joined other nations in ending the use of chimpanzees in medical research.

Today, other nonhuman primates, cats, dogs, pigs, sheep, horses, and many other animals are all still commonly used in federally registered research facilities. The most commonly used animals in research include birds, mice, rats, fish, guinea pigs, rabbits, frogs, and hamsters.



Q: How are animals used in medical research?

Animal experiments conducted within the context of medical research generally fall into two categories: basic (e.g., curiosity-driven experiments) and applied (e.g., drug, device, and vaccine research and development, and toxicity and safety testing) research.

Research is conducted in both the private and public sectors. Animals can be used in research without any limit to the amount of pain they might endure, or any limit to the extent of permanent physical and psychological damage the experimentation might cause. Animals are typically killed after an experiment (or series of experiments) is concluded.


Q: How much money is spent on animal research each year?

It is difficult to know exactly how much money is spent on animal research each year. In 2018, an estimated $606 billion was spent on research and experimental development (R&D) in the United States alone.

The National Institutes of Health is the largest public funder of animal research. In fiscal year 2020, the National Institutes of Health received approximately $40.7 billion toward medical research, approximately half of which was spent on animal research.


Q: When it comes to medical research, what does Phoenix Zones Initiative advocate for?

As part of our commitment to a Just One Health approach, Phoenix Zones Initiative envisions and advances a research agenda that is ethical, effective, and just.

We also advocate for increased investments in primary prevention research and interventions, including attention to social and environmental determinants of health that disproportionately affect underserved and vulnerable communities.

Phoenix Zones Initiative advocates for human research protections—including respect for autonomy (freedom and choice), beneficence (“do good”), nonmaleficence (“do no harm”), and justice—to be enforced for humans and to be extended to animals.

Since they cannot provide informed consent, animals can be considered a vulnerable population, much like some human populations (such as children) are considered a vulnerable population. In human research, vulnerable populations receive specific protections from harmful research. Phoenix Zones Initiative advocates for similar protections for animals.

We specifically advocate for

  1. increased transparency, requiring full public records of all taxpayer-funded research;
  2. the establishment of a minimal risk threshold, much like what is used in pediatric research and for other individuals who cannot provide informed consent;
  3. preferential funding for modern, ethical, and innovative methods; and
  4. the requirement that all federal agencies create a roadmap toward more ethical, patient-centered methods in accordance with the principles established in the The Belmont Report.


Q: If nonhuman animals aren’t used in research, what does that mean for humans?

The history of human research is fraught with examples of unethical practices that exploited vulnerable populations. As adjustments have been made to the prevailing ethical framework, researchers have found new ways to engage with science.

Just as research has shifted within the last century to improve protections for human research subjects, research can shift to improve protections for animals involved in research while still producing knowledge that is beneficial to humans.


Read more about our vision for a more ethical and effective research agenda:

A Belmont Report for Animals?
Reenvisioning Our Research Agenda
Advancing Medical Research Through Ethics and Innovation


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