CDC Seeks to End Program Using Monkeys in Research

On November 21, 2025, Science reported that the Centers for Disease Control and Prevention (CDC) was told to phase out its research on monkeys, which includes approximately 200 rhesus and pig-tailed macaques being used to “study HIV, hepatitis, and other infectious diseases.” According to the news article, the program will reportedly be phased out by the end of the year, though it is not clear what will happen to the animals once it has ended.

The news follows the U.S. Food and Drug Administration’s (FDA) announcement in April 2025 noting the agency would begin phasing out animal testing with “more effective, human-relevant methods,” beginning with monoclonal antibody therapies.

Animal testing is a cruel and gruesome industry where animals are subjected to horrifically painful experiments, often without pain-relieving medication. There is little regulation or meaningful oversight of the labs in which animals are experimented on. For all that pain, experts say that the testing isn’t even effective for the development of drugs that aid humans.

While the FDA’s plan to phase out animal testing and the CDC’s directive to end testing on primates are promising developments, it is estimated that there are over 100 million animals used for research in the U.S. annually — the vast majority of which are mice and rats who are offered no legal protections. Most experimentation on animals is conducted in the private sector and not by government agencies like the FDA and will thus remain subject to experimentation. Both show how much more work is still needed.

The Animal Legal Defense Fund (ALDF) has a long history of taking action to protect animals used for research and their advocates. For example, in July 2024, the U.S. Court of Appeals for the D.C. Circuit ruled that the National Institutes of Health (NIH)’s use of keyword blocking on its social media pages, which censors comments critical of animal testing, violates the First Amendment. The decision came in response to a lawsuit brought by animal activists represented by ALDF and the Knight First Amendment Institute at Columbia University, along with People for the Ethical Treatment of Animals (PETA). In 2025, ALDF achieved a similar victory after the Seventh Circuit Court of Appeals ruled that the University of Wisconsin-Madison’s efforts to censor a former employee of one of its primate laboratories using keyword blocking violates the First Amendment.

In April 2022, ALDF and Rise for Animals (RISE) filed a lawsuit against the U.S. Department of Agriculture (USDA) challenging the agency’s secret policy of only conducting partial inspections of laboratories accredited by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC International), a private organization dominated by the animal research industry. Under this secret policy, the USDA is failing in its duty to conduct thorough annual inspections of numerous animal research facilities regulated under the federal Animal Welfare Act (AWA) — the only federal law ensuring minimum standards of care for some of the animals who are tested on by research facilities. ALDF and RISE were represented by the Harvard Law School’s Animal Law & Policy Clinic.

It is extremely rare for any animal to get out of a research lab alive. However, in July 2024, ALDF helped facilitate the legal release of six Gottingen pigs from an undisclosed research lab to three reputable sanctuaries and made a financial contribution to support the pigs’ care during and after the transition. Gottingen pigs are specifically bred for use in biomedical research, engineered to be small, compliant, docile pigs with good ear veins, that make them easier for researchers to experiment on.

ALDF continues to work throughout the legal system to secure better protections for animals used in research, and better enforcement of those protections.