Some Animals Are More Equal Than Others

Apr 14, 2016

Photo credit: JacobStudio/Thinkstock

By Daniel Engber

I’ve killed birds by suctioning their brains, and I’ve sacrificed the lives of tiny kittens. I’ve withheld water from a live macaque. But in all the time I spent in graduate school for neurobiology, the most diabolical procedure that I performed in the name of scientific research—the one that haunts me still—was my very first: the perfusion of a mouse.

That begins with the animal etherized upon a lab bench, its paws spread wide and secured with tape. I’d snip the skin of its abdomen with a pair of nail scissors, and separate the muscle to expose its heart, smaller than a hazelnut and still beating. The mouse’s own circulatory system would become my instrument, pumping a preservative throughout the mouse’s veins and arteries, so as to pickle every cell inside its body. First I’d poke a hole in the right atrium of the heart, allowing all the blood that’s flowing in to drain into the body cavity. Then I’d slide my syringe into the left ventricle and start feeding it with paraformaldehyde—only so much as the organ could press out with its diminishing contractions. A few minutes later, all the mouse’s vessels would be flushed, made pallid by the chemical, and repurposed for my use. The animal, split open on the table, would have mummified itself before my eyes.

I don’t believe the mice suffered all that much during this process—I’d pinch their feet as I anesthetized them to make sure they were really out, and the procedure had been approved by a standard institutional review committee at my school. But in truth I’d never worked with mice before and had no way to intuit their well-being. (It’s much easier to see pain in the face of a monkey or a cat.) At any rate, it was clear enough that these rodents were disposable: If one perfusion didn’t go so well, I’d simply reach into the cage and grab another mouse. It seemed as though the rules for working with these animals were different from the ones for other species. Bigger, more likable animals were sacrificed for research. Mice were used.

I only learned much later that this disparity has been ensconced in U.S. law for half a century. The Animal Welfare Act, signed by President Lyndon Johnson in August 1966, enforces an apartheid system of concern for animal suffering. This has been the case for most of the law’s history, though in its original formulation, it was intended to protect all warm-blooded animals in the lab. (It was also meant to address a national panic over dognapping.) “Science and research do not compel us to tolerate the kind of inhumanity which has been involved in the … careless and callous handling of animals in some of our laboratories,” Johnson said that summer, at a signing ceremony that was strategically small and out of sight. But within a few years, the U.S. Department of Agriculture—the agency responsibly for implementing the new law—had decided that the rats, mice, and birds in science labs were simply too numerous to be protected. “The math just did not allow it,” a former department official told me several years ago, for another article in Slate. “We couldn’t use the National Guard to make all of these inspections. We didn’t have the force.” On the basis of that calculation, these species were formally excluded.

As we approach the 50th anniversary of the Animal Welfare Act, it’s worth reviewing the legacy of this decision, in both practical and symbolic terms. Rats and mice remain trapped in a special, unprotected category, although they compose a large majority of research animals around the world. Efforts to refine experiments and make them more humane has led to broad reductions in the use of many different species: Numbers from the USDA demonstrate that experiments on protected animals—dogs, cats, and monkeys; rabbits, hamsters, and guinea pigs; and so forth—have been dropping over time and are at a record low. Still, figures on the use of rodents suggest a rapid upward trend. In European labs, rats and mice together represent about four-fifths of experimental vertebrates (a category that includes mammals, fish, birds, reptiles, and amphibians), and their global use now results in more than 100,000 published papers every year.

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25 comments on “Some Animals Are More Equal Than Others

  • High School Turtle Torture
    When I was high school, a biology teacher, Mr. Jackson cut the bottom shell off a live turtle and attached its heart to a lever that charted the twitchings on a graph. I told everyone he was a sadist. Mr. Mackenzie, the principal, called me down to his office and gently chastised me for slandering a teacher. Mr. Jackson reassured me “The turtle feels no pain.” I countered “How do you know?” He replied, “it’s spinal nerves are cut.” I said Well, it sure looks as if it is in pain. It is struggling frantically to right itself.” He responded, “That is just a reflex.”

    He offered “Using the turtle will save many lives. This turtle will last all day. Had I used frogs, I would have had to kill one for each class”. I accused “Your experiment has no point. Everyone already knows that hearts beat”. He said “You are planning a career in biology. You will have to get used to this”. I said “If that’s what it means to be a biologist I want no part of it.”

    Since I am writing this years later, I can compose a better retort: “If you are so sure this will not hurt, how about I poke a scalpel into the back
    of your neck and cut your spinal nerves. Then you can reassure me, based on evidence, that the procedure is painless. From my personal experience, nerves hurt like the blazes when you cut them. Turtle nerves and human nerves are almost identical”.

    That was the last day of my biology career and my first day of animal rights advocacy.

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  • @ first sentence…

    That could be viewed as akin to pulling wings off butterflies, first indicators of later transgressions against humans.

    Rats and mice are great, as snake / bird-of-prey food.

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  • I was a Biology major as a freshman in college. There is this sound that you hear when you pull the skin off of a cat. It is faint for most of the procedure, but, when you get to the area around the tail, it takes more effort and the sound is akin to tearing a bed sheet.

    Performing this procedure convinced me to change to Microbiology. When my advisor asked why i was changing I said “because bacteria don’t scream when you poke them”. My graduate work was in Molecular genetics (micro to molecular — i guess I’d have gone to Nano if it existed at the time).

    Now, as a high school biology teacher, I am gratified that dissection is out of our curriculum. We can do virtual dissections, if the topic calls for it. Now, do not get the impression that dissection is out of the high school experience, kids have the opportunity to dissect in Anatomy and Physiology. This class is an elective and tailored to kids who are future doctors, nurses, researchers etc… But the general student does not have to dissect.

    I love Biology. i do not want anything to suffer at my hand.

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  • 5
    Pinball1970 says:

    No one likes the idea of in vivo research on rodents or any other species and year on year the regulations are reviewed, tightened, amended and so they should.
    I used one rat in two years of A level biology study in the UK, they do not hand them out like sweets.
    University was different but one would hope that a student had made a decent commitment to the future course of study and career by that point.
    Students of biology need to know how animals fit together, work as a complete system, why? Because this is how knowledge is passed on and someday they may become the researcher that comes up with a novel prosthetic or surgical procedure or other treatment than can save lives or improve treatments.
    Current researchers need to use live animals at some stage to either test drugs or for other biochemical physiological study.
    Cut to the last sentence, “their global use now results in more than 100,000 published papers every year.”
    Aside from the ethical question, the best possible welfare of these animals should be a priority as it makes sense in terms of the study, one does not want to add a huge amount of stress and unnecessary amount of pain into the results.
    Not quite on topic but do the same people who cry over the rats also get angry at the medical profession for not helping their sick relative with terminal cancer?
    The same people that try and set free experimental animals from research facilities (that would quickly succumb to disease due to an impaired immune system in many cases) or hound respected scientists whose work could lead to new drugs/treatments?

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  • Given the amount of alternative resources available today: simulators, bioengineering, computational biochemistry, … we need to end or reduce cruel animal testing. Animal welfare laws can still be better developed and also need to spread over the world. Suffering shouldn’t be induced.

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  • 7
    Pinball1970 says:

    @irene-rz “Suffering shouldn’t be induced.”

    Administering drugs, treatment or any sort of invasive investigation cannot be done without some sort of discomfort or pain.
    This is true with experimental animals or patients receiving treatment in hospital.
    Scientists do not want to cause any sort of unnecessary harm to an experimental animal for the sake of it why would they?
    If there was a more effective way to study living systems, than studying living systems, then scientists would employ it, there is absolutely no advantage in taking the long way round to get a result.
    It is generally agreed that antibiotics are or have reached a plateau which will require a paradigm shift very soon in the treatment of infectious disease.
    Animal research will undoubtedly play a key role in this there no escaping that.
    Even with animal testing drug studies can go horribly wrong once they get to the human trial stage.
    As we stand, like it or loath it, rodents play a key role in scientific research for which there is currently no equivalent substitute.

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  • An entirely fruitful mode of reducing the suffering of lab animals is to boycott global brands of toiletries that particularly seek tosell in China (i.e. most). Animal testing is still mandated for them. Own brand products from the big three (four?) UK supermarkets are allegedly testing free as are any other UK only directed products.

    (This information is from my Vegan spy. I’ve not checked it myself but this sounds entirely credible)

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  • The Royal Society’s published position is the consensus among involved researchers.

    Sometimes research may be presented in a crass seeming way- monkey mind control of wheel chairs seen recently here. Someone very close to me would benefit hugely were this technology perfected. Huge swathes of neural prosthetics and pacemakers lie in prospect, transforming aging and diseased lives.

    The tsunami of infection that lies in prospect for the planet will need some innovative technologies, very possibly dependent on whole body systems. Our current “topical toxin” approach with antibiotics is far too open to evolutionary circumvention. We’ve hastened this evolutionary catastrophe almost perfectly, but if not now it would still have happened in the fulness of time. The topical solution fully explorable in the petri dish or the computer molecular simulation etc. is unlikely to meet our complex needs any longer.

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  • 12
    Pinball1970 says:

    @bonnie2 @phil-rimmer
    Industry is constantly being held to account by NGOs like Greenpeace Friends of the earth for using dangerous chemical that end up on consumer products. REACh was introduced in 2007 and policed by ECHA to cut these dangerous chemicals down or ban them completely in the EU.
    Now we have DETOX (driven by Greenpeace among others) which is a directive that is aiming to eradicate dangerous chemicals in production that can end up in the water system but not necessarily on or in the final product.
    The upshot is industry has to substitute those chemicals for alternatives that perform the same function but do not have ecological consequences.
    How do we substitute those functional chemicals with a safe alternative without animal testing?
    This sort of animal testing is just as important but much harder to gain support for.

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  • Phil #9

    The topical solution fully explorable in the petri dish or the
    computer molecular simulation etc. is unlikely to meet our complex
    needs any longer.

    I think it totally necessary that we move on and concentrate our resources in that direction. The confusion needs to be cleared up in the general industry of diagnosis and cross referencing.

    MSG and Me.

    I am further confused by the paper below blaming media for the ‘hype’. (In general)

    Mixed extracts:

    “Why doesn’t everyone in China have a headache?” Jeffrey Steingarten,
    a Harvard Law School gradu- ate turned renowned food critic, poses
    this question

    (Why don’t western people usually suffer Asian Flush Syndrome?)

    MSG, is found in many of the foods they consume on a daily basis.

    however it only functions as an enhancer when it is in its “free”
    form, not when it is bound with other amino acids in proteins In
    addition, it is important to note that most researchers believe that
    once ingested, the human body treats glutamate that is added to foods
    via MSG the same as glutamate which is found naturally in foods, like
    tomatoes or cheese. The FDA requires labeling of all ingredients in
    processed and packaged foods. Therefore, whenever MSG is added to a
    food product, it must be listed on the ingredient list under its
    common name, “monosodium glutamate.” However, when
    glutamate-containing ingredients, such as Parmesan cheese, soy sauce
    and hydrolyzed proteins, are included in a food, they are to be listed
    by their common name. One of the most contested issues that arises in
    the MSG debate is the question of whether to base findings of MSG
    safety solely on double-blind scientific studies or to take into
    consideration the anecdotal evidence. A study by two Italian
    scientists, P.L. Morselli and S. Garatini of the Institute of
    Pharmacologic Research in Milan, indicated that CRS may ultimately be
    a result of “autosuggestion.” the number of anecdotal reports
    continues to grow

    Note; The quotes above seemed to have merged into one!

    Before I knew what MSG even was;

    Panic attacks in restaurants, especially Pizza Hut (Not a restaurant 🙂 ), where I would have to leave my children and wife inside while I had to go get some fresh air and try to hide my pacing up and down and try to resist the urge to run away. Some shaking.

    A couple of years later when at a birthday meal at a restaurant, Chinese, I started to shake a little and my heart rate went up after the constant supply of starters. Tried to hide it. I looked over at the birthday girl, who had been suffering from a particularly bad cold, who was beginning to look ill and very white and was shaking. She was finally so bad she was taken home by which time I was feeling a little worse also. We managed to finish the meal and not stick around as the birthday girl wasn’t there. As I walked out into the car park and the cold hit, I started to shake so much my wife had to take the wheel. I carried on shaking until I pulled a muscle in my back and had to have a week off work.

    The following day we called to find out how the birthday girl was and were told she had been to the doctors and was told she had a bad reaction to the MSG. That is when I found out what MSG was and what to avoid.

    After knowing;

    I have tried to keep away from it. Although it is tasteless and odourless, I seem to be able to taste and smell the stuff getting better at recognising it as time goes by. My body seems to have found another way of detecting it?

    I am suspicious of being told the body handles the substance the same in natural form and as an extraction. I love, and crave, tomatoes and can not detect it in any way but could ‘smell’ the stuff on my chicken wrap last night and only ate one piece so my granddaughter would eat her meal. More and more Turkish restaurants seem to be using it and is known as “Chinese salt” to them. Being Turkish my options are narrowing as to where I can eat. I also love oranges. If I eat an orange I am fine but if I have more than a tiny amount in juice form, well…. it goes through me like a dose of salts, as it were….

    I have an auto immune disease which could be a factor or my genetic makeup might have an effect but the original question at the top is a silly one and shows scientific cross referencing isn’t quite good enough in fields and computer simulation will be the way forward as animal testing is failing.

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  • 30 years ago I was a research assistant helping with a study of muscle spindles in jaw muscles. This involved vital perfusion of a couple dozen newborn hamsters. Even though there was approval from the IRB and the animals were well-anesthetized, I’ve been critical of animal research ever since. I understand that there are some questions that can’t be answered without such work, but I take a dim view if it’s not actually necessary.


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  • Most of the replies have focused on animal testing as a way of curing debilitating and life threatening illnesses. I suspect however that the majority of tests done on animals are of a more mundane variety – a new brand of eyeliner perhaps, or yet another treatment for ED.

    Part of the ethics of animal testing should concern itself with the use to which we put the data. I’m aware that many of the products we employ to make ourselves look pretty or smell nice, (and yes, to be able to have erections that last more than four hours), most of these products were originally tested, in vast overdoses, on poor animals. These animals suffered and died for our vanity which quite frankly is despicable. Despite this we now have a small but strong movement to boycott these products. I of course support this, but I think governments need to go further and mandate that if animals suffer in our name they do so for noble reasons, and not the self-serving interests of the toiletries and pharmaceutical businesses.

    On a side note, I agree with the premise of the original article. Why is it OK for example to make a rat suffer but not a kitten? Rhetorical question.

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  • Why is it OK for example to make a rat suffer but not a kitten? Rhetorical question.

    Its a good question…

    A cat has ten times the neuron count of a mouse and four times more than a rat.

    Pain that happens to us suddenly without anticipation and subsequent introspection about its repeat is far less stress inducing and is often handled by adrenaline uplift and an automatic mode that gets us through. Torture is effective precisely because it plays on anticipation and introspection. This takes grey matter.

    The less aware animal is preferred where the model of what is to be studied is sufficient. Fruit flies in preference… (Lobsters are only 40% as brainy as fruit flies! They are giant but rather primitive “insects” and have fringe benefits.)

    Also, in picking on the unlucky few animals to suffer we at least build up more expertise in the specifics of the model accuracy over the spread of areas examined and may thus be better predictive in new areas of problems needing revised methods with reduced waste time and reduced animal harming.

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  • Olgun,

    The very last thing either glutamic acid or one of its glutamate salts is, is tasteless.

    This is the single best researched article on the subject out there-

    A few people undoubtedly have a substantialy negative response to its appearance in foods. As a flavour enhancing condiment (as a glutamate salt like MSG) it is very possibly to receive particularly high doses and for its effects to be more noticeable.

    Like lactose intolerance (not possessing the evolved breakdown chemical lactase) or gluten or alcohol intolerance, it is entirely likely that the food eating cultures in your past have not equipped you as well to handle certain “foodstuffs”. A culture without seaweed consumption or tomato consumption or hard cheese consumption may fail to provide the digestive machinery to breakdown the glutamate/glutamic acid before it gets absorbed by the gut and gets into the blood stream. If any crosses the blood brain barrier (and this may be the evolutionary differentiating point alternately) because it is a powerful neurotransmitter, basic system controls in the brain stem may start to go little awry.

    My brain is somewhat hooked on coffee. In micro-electronics prototyping I need very steady hands. I don’t have them any longer until two heaped coffee spoons of Gold Blend are circulating in my booldstream. Receptor sensitivities have been skewed by my persistent blood chemical offset and homeostasis, as ever, resets to a moving average. (Thats all it can do.) Maybe, slow acclimatisation to raised glutamate levels is possible?

    Just a teensy bit of marmite on your toast in the morning?

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  • @phil

    A cat has ten times the neuron count of a mouse and four times more than a rat.

    That may be. It’s not the reason we use rats and mice for experiments. They are preferred over cats (and other mammals) because:
    – they are small and easy to handle
    – they are cheap and abundant
    – they closely resemble humans in their biology and behaviour
    – a small industry has built up supplying them for research
    – their anatomy and physiology is well studied
    – and of course, the hundred million or so we kill a year don’t make the headlines the way that the deaths of a hundred million kittens would. That’s just in the US by the way.

    People who experiment on animals do not choose one particular species over another for any altruistic reason. Low cost, abundance, ease of handling, ready availability, convenience – all play a part. Less suffering? Sadly, no.

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  • john.wb #21

    I think you use some of my points back to me.

    More pertinent is that mice and rats are caught and killed as vermin.

    Cuteness and attractive human like behaviours is highly correlated with brain power and awareness. Kittens have far more adorable and varied behaviours than mice, purring, playing, acting fierce and soppy. This is all grey matter at work. More sentient animals used always gets more pushback and distaste. Who is fighting for the fruitfly?

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  • Thanks Phil.

    The very last thing either glutamic acid or one of its glutamate salts
    is, is tasteless.

    I haven’t any special powers then 🙂 . I should have listened to my body instead of listening to the rubbish I read.

    Thanks for the link and helping me to sort through the mess.

    Just a teensy bit of marmite on your toast in the morning?

    I’m on the hate side of the Marmite debate!!
    I have developed a lactose intolerance over the last eight or so years also. Like the effects of the MSG, I can eat somethings that seem to have varying amounts of effect on me but a drop of milk in my tea or coffee and I begin to feel the effects more. Getting older must have its effects as well.

    Beef tomatoes which might have figured more in your immediate cultural

    Spot on!!!!!!


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  • Thanks for raising the issue, Daniel Engber. Some animals are indeed more equal than others. You could stop all animal testing tomorrow, and there would still be roughly 70 BILLION land animals mutilated, tortured, and slaughtered every year for no reason other than we were all taught to like the taste of them. These sentient animals (mostly cows, pigs, chickens, turkeys, and lambs) have similar intelligence, social structures, and ability to feel pain as lab mice or our pet dogs and cats do, but somehow everyone thinks it’s OK to cause massive suffering to one group but not the other. Hopefully more people will question the status quo and realize that all these animals deserve our compassion and not to instead be treated like unfeeling, disposable commodities that they are today.

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  • Christopher Harris #24

    70 BILLION land animals mutilated, tortured, and slaughtered every year for no reason other than we were all taught to like the taste of them.

    Myself, I don’t want to be mutilated or tortured. I have though offered that I become dog food for some little old ladies companion dog when I die (hopefully at a time of my choosing).

    Meat need not be murder. Driving up animal welfare should be the focus of all our activities. It is the fastest way to ameliorate harms. Living with animals is good for us I contend. I believe we can encompass the love and the loss of others the better for their humbling presence.

    Selecting species to live in holiday camps, with dental, freedom from parasites and predators (excepting ourselves) and living longer than the average life of their sparse wild counterpart, just failing to wake up one morning, might be a proposition they might choose for themselves….

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