Drugmaker Merck & Co. is joining two dozen other pharmaceutical companies and contract laboratories in committing to ending research on chimpanzees.
The growing trend — driven by improved technology and pressure from animal rights groups as well as the National Institutes of Health and Congress — could mean roughly 1,000 chimps in the U.S. used for research or warehoused in laboratory cages could be "retired" to sanctuaries by around 2020.
That is according to the Humane Society of the United States, which called the move a "step in the right direction" and which seven years ago began urging companies to phase out all chimp research.
Merck directed Al Jazeera to a statement on its website in which the company said it has "voluntarily made the decision not to use chimpanzees in biomedical research in the foreseeable future or to directly or indirectly fund their use in studies by external research partners" due to what it called "scientific advances."
The statement also described research on animals as an essential part of the firm's work.
"The company's mission is to discover, develop, manufacture and market innovative medicines and vaccines that treat and prevent illness. Animal research is indispensable to this mission," Merck said.
Kathleen Conlee, the vice president of animal-research issues at the Humane Society, told Al Jazeera on Thursday that the organization feels Merck's decision is part of a larger trend away from animal research and is "another example of the direction we're moving in."
Conlee said that about 840 chimpanzees are kept in labs across the country today and said that in recent years, they had been used by companies to do research related to hepatitis C.
"We don't know how many are being used at any given time," Conlee added.
Last June, reacting to an Institute of Medicine study Congress had requested, which found that nearly all chimp research is unnecessary, the NIH announced it would retire and send about 90 percent of government-owned research chimps to the Chimp Haven sanctuary in Keithville, La. It's now home to about 160 chimps, with nearly 60 more to arrive soon.
After several years, the NIH plans to decide whether the remaining chimps in government labs can also be moved to sanctuaries.
Nearly all animal experiments in the U.S. involve mice, rats and guinea pigs, although some are done on dogs and great apes, almost always chimpanzees.
But animal research, particularly on primates and pet species such as dogs and rabbits, has long drawn criticism from animal rights groups, including protests outside laboratories and at annual shareholder meetings. Besides calling the practice inhumane, activists often have alleged — and sometimes proved — that animals were being abused.
Many companies previously said it was necessary to test potential medicines and vaccines on nonhuman primates because they needed an animal in which the anatomy and disease course were very similar to that in humans.
That thinking changed as technology allowed researchers to do initial testing via computer simulations, in bacteria or cells and in animals as small as fish. Many drugmakers also found ways to do testing on far fewer animals and to limit the discomfort of experiments by using painkillers and tranquilizers.
British drugmaker GlaxoSmithKline PLC was one of the first to stop research in chimps, back in 2008.
Chimpanzees used for commercial medical research generally are confined in the labs of contract testing companies, and the Humane Society is trying to convince those companies that there's no longer enough demand to continue warehousing chimpanzees for potential future work.
The organization hopes drug companies will pay to support those chimpanzees in one of five U.S. accredited sanctuaries for former research chimps. The Humane Society also continues to push for wider use of non-animal alternatives in medical research and to call for government investment to find those alternatives.
"We want there to be non-animal alternatives used when possible," Conlee said.
Philip J. Victor contributed to this report, with The Associated Press.