The HSUS Undercover Investigation at Charles River Mattawan

The Humane Society of the United States placed an undercover investigator inside Charles River's Mattawan, Michigan facility for “nearly 100 days” between April and August 2018. The investigator documented “nearly two dozen” experiments involving dogs.

On March 12, 2019, HSUS publicly released video and related materials. The press release named four entities whose work was depicted: Dow AgroSciences, Corteva Agriscience, Paredox Therapeutics, and Above and Beyond NB, LLC.

The sponsor (Dow AgroSciences/Corteva) ended the one-year pesticide test within days of the video release. In a Twitter-posted statement, Corteva said it received confirmation from Brazil's regulator — Agência Nacional de Vigilância Sanitária (ANVISA) — that animal pesticide testing would no longer be required, and therefore the study would end.

HSUS characterized the one-year dog test as scientifically unnecessary, noting that the U.S. had eliminated it as a requirement more than a decade earlier. The specific dispute centered on international expectations — Brazil in particular — not U.S. domestic regulatory needs.

HSUS reported it “convinced” the company to release the beagles to Michigan Humane Society for preparation and adoption. The shelter plan included behavioral assessments (dogs were not used to leashes or the outdoors), independent veterinary assessments, and likely foster placement, supported by an HSUS grant.

In March 2020, STAT reported that biotech client Paredox Therapeutics filed a lawsuit accusing Charles River of allowing confidential trade secrets to be disseminated after the HSUS undercover agent filmed dog experiments and publicized them online. The suit alleged screening and supervision failures that permitted unauthorized access to highly confidential procedures.

The case was filed as Paredox Therapeutics, LLC v. Charles River Laboratories International, Inc. et al, case number 1:20-cv-10464 (District of Massachusetts), before Judge Indira Talwani.

HSUS's 2019 materials had explicitly named Paredox among the companies whose dog experiments were shown in the video, including footage of a beagle named “Harvey” used in a Paredox-sponsored study.

After the video release, Charles River issued a statement asserting that it follows federal laws and international standards and operates “consistent with” a commitment to animal welfare and ethical treatment — framing its responsibilities as both animal care and scientific research stewardship.

No public, detailed description of specific post-investigation changes to hiring or security screening at the Mattawan site was found in retrieved sources. Charles River later acquired MPI Research (the Mattawan campus operator) for approximately $800 million in early 2018, expanding its early-stage CRO capabilities. The company now reports quarterly revenue around $1 billion, consistent with approximately $4 billion in annual revenue.

Charles River's CHARTER program (Commitment to Humane Animal Research Through Excellence and Responsibility) predates the investigation, having been established in 2009. In 2023, the company established an Office for Responsible Animal Use (ORAU) and adopted a “4Rs” framework: Replacement, Reduction, Refinement, plus Responsibility.

Prior to October 2007, EPA required both 13-week and 1-year beagle dog studies for pesticide registration. An EPA-authored retrospective analysis concluded the 1-year requirement should be eliminated, and the U.S. dropped it.

However, a 2024 EPA policy document notes that while many statutes allow flexibility to incorporate New Approach Methods (NAMs), vertebrate testing is still mandated for certain pesticide evaluations in Title 40 CFR. Animal testing requirements for pesticides have not been fully eliminated and remain embedded in parts of the regulatory framework — particularly for international registration where other countries' requirements (like Brazil's pre-2019 stance) can force additional studies.