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Consider the Mouse

Published on: December 6, 2019
Published in: Hastings Bioethics Forum

The American species of the common house mouse (Mus musculus) does an odd thing when going through opioid withdrawal. It jumps involuntarily, rearing up on its hind legs and leaping 3-to-4 feet in the air. I was a spectator to this phenomenon this summer, while working at a research hospital in New York City.

On the bottom floor of the hospital is what doctors affectionately call the mouse house. Mice in the mouse house live an abnormally comfortable life—relative, at least, to the majority of their species. Cages are filled with ample food and water and cleaned daily. No more than five mice are allowed in each cage. Of course, the one drawback to the relatively comfortable life these mice lead is the experiments performed upon them. In my case, this involves injecting mice with novel opioid compounds and testing for analgesia and drug tolerance.

Talking about quality of life for these mice, though, is already a tricky subject, since the only reason these mice are alive is for scientific research. The mice are genetic variants bred so as to be useful for research. There is a teleological purpose to their life and death in the pursuit of science. Or so I tell myself when placing mice in CO2 chambers and then dislocating their cervical spines to access their brains for further analysis

But moral qualms become more pronounced as a minor mouse genocide begins to rest on my conscious. Certain questions become unavoidable. Is it morally acceptable to inject compounds with unknown physiological effects into sentient beings, who are later killed in the name of science? Is it ignoble to ask this question as a scientist?

Members of People for the Ethical Treatment of Animals would have you think that all of this is inhumane and immoral and unequivocally wrong. Presumably, the moral thesis promoted by PETA activists is one about pain, discomfort and death; to a PETA activist, the employment of sentient mammals as the testers of compounds of unknown effect and the subsequent pain and death inflicted upon them is wrong.

So how do we begin to even tackle the morality of the use of animals for scientific research?

Questions of how different kinds of animals experience pain, and of whether it might be justifiable to inflict pain on them in pursuit of scientific discovery are complex. Even defining what counts as pain is difficult, since it is mainly a subjective phenomenon. Though there are easily recognizable indications that signal pain from a human subject to a human observer, identifying objective measures of pain in other species is significantly more challenging. Moreover, how we ought to respond to their indications of pain are questions of philosophy—metaphysics, epistemology, ethics, value theory.

As a test just think about watching a friend of yours squashing a cockroach on the ground and seeing it writhe around. Next switch that to a lizard; now a mouse; now a dog; now a human. If you are a “normal” person, my guess is that you have a different gut moral response as you imagine each hypothetical situation. Hopefully one of increasing disgust, such that by the time your friend is squashing another human you have decided that you need to pick your friends more wisely. But the question of why you feel so differently about a bug’s pain and a mouse’s and a human’s is the stuff that philosophers find so interesting, especially because by the time you get to a mouse (or any mammal for that matter), the neuronal pathways that constitute pain are more or less the same as any human’s. This is, of course, why mice are used in scientific research on pain and pain medications.

Most ethicists hold that there are two criteria that determine whether an animal has the capacity for suffering—and thereby warrants our moral consideration. The first is neurological: does the animal have the hardware required to experience pain? The second is behavioral: does the animal behave in such a way as to indicate the experience of pain?

Most animals (from bug to human) fulfill the first requirement. Pain reception is part of an extremely old and evolutionarily beneficial neuronal pathway managed by nociceptors, histamines, bradykinins, prostaglandins and opioid receptors. This is what controls our unconscious, instinctual reaction to pain. It is why, for example, we pull away immediately after touching the electric stove we had believed was off.

The second criterion is more about an animal’s experience of pain, controlled in humans and other mammals by the cerebral cortex. The cerebral cortex allows us to associate stimuli with a feeling of distress or unpleasantness. It allows for an experience of pain beyond just instinctual response. It is why we know in some intellectual sense that touching a fire will be emotionally unpleasant for us.

I’m left with the image of mice showing clear signs of distress and discomfort, throwing themselves into the air because of a drug that I prepare and inject into them. Their response to pain is, by any ethicist’s definition, not so different from what yours or mine would be. The mice have an interest in ensuring that this experiment is not done to them. In fact, researchers often have to switch the mice they work on when the mice come to recognize them by their smell; mice eventually become much harder to handle—making an effort to avoid the inevitable discomfort they associate with the person’s scent.

These are realities of modern science, what I believe to be necessary evils involved in the pursuit of better human life. My initial reaction to PETA activists then, is that they are overly dogmatic. And yet when I truly interrogate my conviction, I’m forced to admit that the reason their position seems extreme to me is based on some unsubstantiated belief that animals are in some way less morally important than humans. That is, mouse suffering and death are justified by as little as the possibility of making scientific breakthroughs that could help human life.  

But even asserting this belief, forces me to acknowledge that it belongs to a self-interested ethical system that I may not be able to justify. I have only a vague notion that this belief is truly defensible rather than merely convenient. For now, though—with so much mouse death and suffering already on my hands—this self-interested belief may have to suffice.

Gabriel Redel-Traub is a medical student at New York University School of Medicine. David Foster Wallace’s essay, “Consider the Lobster,” was a major inspiration for this piece.

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  1. Bruce A. Middleton, JD CAC(1986-1994) on

    Actually the behavior in mice may be novel to scientific researchers, there is a reason why addicts have long referred to the process of heroin withdrawal as “kicking” dope. The intense leg spasms are well known to any person experiencing narcotic withdrawal beyond minimal or medically supervised situations.

    And, because I’m ‘that’ kind of person, I wonder if indeed this issue “….begins to rest on my conscious. ” or perhaps on your conscience?

    Thank you for your thoughtful and insightful exploration of this issue of ethical and societal concern.

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