I work in a university research lab that works on brain development. One of my duties is taking care of our lab mice, which includes setting up matings, appliying ear tags, and killing mice.

When I chose this career path the option of having to work with mice was there, but I thought I’d be able to avoid it. Simply apply for jobs in the non-mouse labs – can’t be that hard, can it? What I underestimated was just how ubiquitous animal testing still is. Here I am now, 7 years into my career, and as it turns out almost everything is tested on mice. This is especially true in medical science. Nobody seems to mind that there are serious doubts regarding whether or not it's actually working.

In the interview for my current position, I was open with my aversion towards animal work. It was agreed that my duties would only be basic husbandry, which I didn’t think I’d be losing any sleep over. I would have to kill some mice from time to time, but mostly I'd set up a few matings, take care of the database, and work in the proper lab the remaining 80% of the time, doing what I love: Science.

I wouldn't have to do any of the truly grisly stuff. I would not have to do intracardial perfusions, which is the technical term for anesthetizing a mouse, cutting it open, cracking its ribcage, and plunging a needle into its still-beating heart so that the mouse's cardiovascular system spends its last minute helping you pumping the fixative into even the tiniest blood vessels of the brain. For the ones among you that are more brave and curious than sensible, here's an instructional video. My recommendation is to not watch it before lunch.

But the grisly stuff is not what bothers me. At least the animals are anesthetized for this. What bothers me is the stuff we do to them without anaesthesia. To start, we apply ear-punches as a means of identification as well as to get some tissue samples for genotyping. The tool for ear-punching looks like little scissors, only instead of blades there's a blunt metal pin on one side and a simple hole on the other. It is not a high-end tool. The low quality means that, about 30% of the time, it does not punch clean holes into the mice's ears like it’s supposed to. Instead it just makes a crescent-shaped tear, and we have to either try again or just pull until the rest comes off. The feeling of tearing tissue is not something I think I’ll ever be able to forget. Raising this issue with the ones responsible resultet in a shrug and a "yeah the tool is kinda crappy, you have to get used to it."

We keep five of them in a shoe-box-sized cage at the best of times. The cages are often overcrowded way above this limit. Only temporarily of course, “just two, three days until the results are in.” Many professors, students and caretakers see nothing wrong with this. But in practice this means that there will be several overcrowded cages at any given time, giving the lie to the claim that this is only ever a temporary exception.



We kill them for little or no reason. Mouse lives are cheap. This has two reasons: First, cages are expensive. So killing mice and breeding new ones whenever they’re needed is cheaper than trying to expand the number of cages, and publicly funded research is always looking for ways to cut corners in maintenance costs like this.

Secondly, cage space is real estate that is constantly fought over in university politics. Professors who don’t need their cages will do everything to keep them anyway, because just sitting on unused space is always better than having to re-apply for it in the future.

Reduce, Replace, Refine

All this results in a careless waste of animal life. There is a glaring gap between this everyday reality and the progressive ethical theory, the tight government regulations, and the lofty goals of research institutions. Above all there is the ever-present lip service being paid to the 3R: “Reduce, Replace, Refine”. But this concept is an obstacle to its own implementation, for „Reduce“ and „Replace“ will never happen as long as the research community frantically clings to animal models as the gold standard™ of the review and publication system. The concept of 3R however is a pillar of support for exactly this kind of frantic clinging-on, because it serves as the fig-leaf of a broken system.

Many mouse lines are fertile till well over a year, but I’ve rarely seen anything older than three months used in breedings. Which means that anything older than three months will sooner or later get killed to make space, which in turn means we need to breed more to keep the numbers constant. And so the circle keeps rolling.

In everyday handling, it’s hard to avoid making the mice suffer. Mice are animals of flight, and being held terrorizes them. Which means that even being as careful as I possibly can, I still have to grip them by the scruff of their neck so tight that it makes their eyes bulge. It's the only way to hold them still enough to be able to mark their ears. It's also the only way to not get bitten. Base-of-tail- and Scruff-of-the-neck-handling is still state of the art, by the way. Of course methods for “non-aversive” handling have long been available, but the news seems to travel slow through the scientific community. Probably because only behavioural researchers care about the stress levels of their mice anyway, while the rest of science cares about being able to handle mice quickly and securely, which translates to lower costs.

Last but not least there's the incompetence of students. I don’t blame them – These are PhD-students get paid for a 50% position but are expected to work 60+ hours a week. Students who are permanently stressed, poorly supervised, and only ever receive a 10 minute alibi of an introduction to mouse work, all of which they’ve long forgotten by the time they actually start working with mice. All this means they constantly overestimate what they can do, underestimate the amount of cage-space they’ll need, forget to update the database, mislabel their cages, fail to stop breedings on time, and as mentioned before, overcrowd cages “for just a few days”.



Nobody cares

The public more or less willingly turns a blind eye to this all. Even animal-welfare advocates let themselves be lulled by some simple number-fixing. In the EU for example, numbers are being reported for animals “used in experiments”. Few people realise that almost none of what I described so far shows up in the statistic, because husbandry is not an “experiment”. It’s preparatory work for experiments. All those generations that lead up to a mouse that has a specific genotype, all those that carry not all of the desired genes because the student got confused and put the wrong mouse in a mating, all those that simply belong to the high percentage of offspring that don't carry the desired mutation even if the mating was set up correctly, all those mice that just got too old to use while other stuff elsewhere in the university caused a delay - All those don't show up in the statistic. Only a handful of animals end up being experimented on. The suffering that is part of preperatory breeding and simple upkeep doesn’t seem to be worth mentioning, even if this is where 90% of the animals live and die.

In a lab meeting last week we discussed the publication of a "parkinson model", which the authors proudly presented to the world. They quantified the state of disease by making the mice climb a pole and measure how long they could hold on before they fell. They tried to make a homozygous line (Mice, like humans, carry two copies of each gene. “Homozygous” means that both copies are altered rather than just one of them) but they note that this line is hard to breed because the mice have tremors so bad that they can scarcely reach their food. But hey, who doesn't want to cure Parkinson's? Please note that there was not even an attempt at a cure involved in this research. What was being celebrated as a breakthrough in the field was successfully inflicting our disease upon another species. Yes of course this is done in the hopes of finding a cure one day, but in cancer research for example mice have had tumors induced or implanted since the 70ies, and we haven’t exactly made strides towards anything. In the clinic, we still use good ol’ chemotherapy, the trusted blunt warhammer among the toolbox full of surgical knives.



We can do better

Meanwhile, there are alternatives. In the same time frame that continued mouse work got us exactly nowhere, stem-cell research has been making actual strides. Ever since 2006, we don’t even need embryos anymore – we can revert most cells back to stem-cell status. Nowadays we can grow close to any human cell type in a dish. This means we can test, say, the cardiotoxicity of a drug on actual human heart-muslce cells rather than do our drug-testing on the hearts of living monkeys and mice followed by amazement when it takes until the first clinical trials until it turns out that the drug is toxic to humans after all. Results from testing on human cells, despite all imperfections, translate much better into clinical reality.



Of course even stem-cell research has its shortcomings. The 2006 discovery of induced pluripotent stem cells (iPSCs) was a truly amazing breakthrough, but of course it turned out not to be a panacea. Despite this amazing tool, we still haven’t cured cancer. Or Parkinsons. Or MS.

But I can’t help but imagine how much further the field would be if it was fully embraced and developed as the new standard. I can’t help but imagine that if we fully committed to finding something better, maybe we could finally end this nightmarish treadmill of casual animal cruelty.