The Humane Society of the United States is pushing for the release of three dozen dogs from a western Michigan laboratory, alleging that an undercover investigation found that they are being fed fungicides.

The animal rights group on Tuesday released the findings of its investigation conducted last year at Charles River Laboratories in Mattawan, which is about 10 miles west of Kalamazoo.

The Humane Society said it documented nearly two dozen experiments that involved animal testing.

“Our investigator, who spent nearly 100 days at the facility, documented the dogs cowering, frightened, in their cages with surgical scars and implanted with large devices. Dogs being force-fed or infused with drugs, pesticides and other products, using crude methods, many that are unlikely to ever be used in humans,” the Humane Society said on its website.

The group said one experiment involves 36 beagles that are being used in a yearlong pesticide test for a product being developed by Corteva Agriscience, which is a division of DowDuPont Inc. It said the dogs will be euthanized in July and is seeking their release so the organization can help find them homes.

Dow Chemical, which previously oversaw a fungicide business that’s now under Corteva and DowDuPont, said the company is looking for alternatives that wouldn’t involve animal testing.

“Animal testing is not something Dow undertakes lightly, but neither is it something the company can discontinue when it is required by regulatory authorities. Dow keeps its use of animal testing to an absolute minimum,” Dow Chemical said.

The animal testing is required by regulators in Brazil, Corteva said in a separate statement.

Animals are essential to understanding disease progression and drug safety, Charles River Laboratories officials said. When animals are used, the lab works to treat them in a “responsible, ethical and humane” way, officials said.

“As animal caregivers and scientific researchers, we are responsible to our clients and the public for the health and well-being of the animals under our stewardship, and we strive to fulfill that responsibility on a daily basis,” the lab said.