How mice are like humans, how they aren’t, and why it matters

By Kathy Guillermo

A recent study published in the journal Science Advances concluded that mice can transfer their heightened pain sensitivity to other mice through scent cues. This paper is the latest in a long line showing that these tiny animals deserve our respect, yet the very people who gather the data fail to draw the obvious conclusion: We must stop treating mice as though they have no emotions or feelings — because it’s been proved over and over again that they do.

To reach this latest conclusion, experimenters at Oregon Health & Science University (OHSU) first had to make mice acutely sensitive to pain — a terrible process in and of itself — and then determine whether other mice had become super-sensitive by inflicting additional painful procedures on them.

Certainly, nothing good came of this study for the mice involved. Some were injected with a substance that induces long-lasting inflammation. Others were addicted to morphine or alcohol and then made to endure an agonizing withdrawal process.

They were poked with plastic filaments. Their tails were dipped in hot water, and their paws were injected with an irritant to see how much they licked the site.

If these inhumane procedures had been inflicted outside the laboratory, they’d have warranted cruelty-to-animals charges. But mice in laboratories are exempt from even the most meager of protections under the law. Under the federal Animal Welfare Act, they aren’t even defined as “animals.”

Other studies have shown that mice form long-lasting bonds, are good mothers, feel empathy and even giggle (at frequencies that we can’t hear). They have a fundamental right to live without being tormented by humans.

But that’s not all that’s wrong with imprisoning and exploiting mice in laboratories. While they are like humans in many ways, such as the ability to suffer, in others, they are entirely different.

There is abundant evidence that experiments on animals rarely yield findings that end up being clinically useful for humans. One study found that fewer than 10 percent of promising discoveries coming out of basic animal research make their way into clinical use within 20 years.

One large, multi-institution study found few similarities between the genetic response in mice to things that cause inflammation—such as burns, trauma and infection—and the response in humans. In some cases, the reactions were actually the opposite.

And dozens of papers are released each month on rodent studies of diabetes, despite vast differences in the way rodents regulate glucose and the way the disease progresses in them compared with in humans.

By any definition, that’s a pretty dismal track record.

“I think we’ve got ourselves into a mess right now, with lab mice in particular.”

That’s Joseph Garner, an associate professor in the Department of Comparative Medicine at Stanford University, speaking in a recent interview in New Scientist magazine. Garner says that researchers need to ask themselves if animals are truly modeling human disease. “Increasingly, they are not,” he says. “So we end up learning a great deal about how mice respond to various compounds, but it’s irrelevant to humans and an enormous waste of money.”

What is relevant to human medicine is research that uses superior non-animal methods, such as sophisticated computer modeling, engineered human tissue and organs on microchips, which can gauge the effectiveness of drugs on human cells. In fact, Harvard University just announced the development of a 3-D-printed heart-on-a-chip, which will pave the way for rapid customization to an individual patient’s cells.

So perhaps it’s time for OHSU—and others who continue to conduct archaic experiments on animals—to embrace modern, non-animal research methods and develop some empathy of their own.