Mice and rats make up the vast majority of animals used in experiments. PCRM recently received documents through the Freedom of Information Act that reveal how badly mice and rats are treated at some of the nation’s top-ranked universities. The following incidents occurred at Ivy League universities and were revealed in communications with the National Institutes of Health:

• Yale University
  • More than 75 mice were crowded into a single cage. The cage was found to contain many layers of both live and dead mice.
  • When administrators asked experimenters to stop performing unapproved procedures on rats, the experimenters refused, killing 20 rats.
• Dartmouth College
  • On several occasions, live mice were found in carcass disposal bags after laboratory staff thought they had been euthanized.
  • A rat was scalded to death when he was sent through a cage washer.
• Princeton University
  • Four mice were injected with a “pseudo rabies virus” and then killed in unapproved experiments.
  • Four rats died when caretakers failed to feed them for three days.
• Brown University
  • Two rats starved to death in their cages, unnoticed by animal care staff.

The incidents above are just a few of the many that occur all the time. Yet no federal law protects mice and rats from the cruelest experiments or even requires that they be given pain killers because the Animal Welfare Act explicitly excludes them from its definition of “animal.”

Due to the lack of legal protection and transparency, mice and rats are often treated very poorly with few consequences. They routinely die due to overcrowding in cages, starvation, dehydration, or use in unapproved experiments. With many large facilities each holding 100,000 or more mice and rats, tens of millions are at risk across the country.

If this carelessness and neglect had involved chimpanzees, dogs, or cats, the U.S. Department of Agriculture would have included these situations in inspection reports freely available to the public. Instead, the incidents go virtually unseen, with institutions responsible for policing and reporting their own care of mice and rats.

In addition to the deaths caused by animal welfare deficiencies, mice and rats are chosen to suffer through some of the most excruciating experiments. They are burned or forced to swim until exhaustion in pain and fear experiments. They are genetically modified to develop massive tumors. And they undergo nerve agent attacks without anesthesia or pain relief.

Research has shown that mice and rats experience a complex variety of emotions. Rats enjoy being tickled and laugh much like humans do, and mice in pain exhibit easily recognizable winces, grimaces, and other facial expressions.

As we work to end invasive experiments on great apes, heartbreaking cardiovascular experiments on dogs, and medical training on pigs, goats, cats, and ferrets, it is important to remember that millions of intelligent mice and rats are also needlessly suffering. They are a forgotten 99 percent.