One day with lab mice

Introduction: I work as a student assistant in our university’s mouse lab where I mostly help out the caretaker. This is one lab out of many in existence and not every lab is the same, especially because our mice aren’t used for live experiments (if you count out “waiting for a tumor to grow”). So, enjoy this piece of half-fiction!

The door squeaks open as I have to lean heavily against it, because the pressure from the inside tries to keep it shut. I still haven’t completely understood why we have to work with a higher air pressure than usual, but it has to be important for something.

After changing into my work clothes and putting on latex gloves, I greet my boss, who sends me away to fill and replace the water bottles. Great. With about 300 cages, this always takes a while.

As I walk down the rows, I peak into every cage to check if everything is alright. Of course, my boss would repeat this later, but there is always the off-chance that I’d discover some newborn mice. I would be allowed to take them out, count them and check if they are healthy!

But, no luck today. Rachel is looking particularly fat today, but she just refuses to give birth. To be honest, I would too in her place. She’s one of the big, white mice and they usually have between ten and 24 babies. That’s definitely no walk in the park.
Francesca on the other hand has been lucky. She belongs to the smaller, black mice and they rarely have more than 6 babies. They look a bit like pink peanuts when they’re still small, with their closed eyes and hairless bodies.

I really shouldn’t name the mice, it’s too easy to get attached. But it just happens sometimes. And after a year, you have some favorites.

Whistling, I roll the cart with the bottles into the next room and start switching out empty bottles for full ones. Then I stop.
“Hey, boss?”, I call out. “What happened to the old ladies?” Lab mice rarely get a lot older than one or two years, but “the old ladies” was a group of 5 female mice that had succeeded in making the two years and still looking fit.
“The pharmacists needed them as a control group for that liver cancer thing. They took them yesterday.”

My heart sinks down in my chest a bit. It’s easy to forget that most of these mice are needed for science. They were bred for science, if you count out those that were accidentally conceived because someone mistook a male for a female and put it in the wrong cage.

I finish the water bottles and soothe my bleeding heart by changing cages. The cages are see-through plastic boxes with a snap-on lid, so you just take the dirty one, take out the mice, put them in a fresh one and snap the lid back on.
Some mice hate being switched, but especially the very young and very old ones enjoy the distraction. I take some extra time to let them climb over my gloved fingers. They’re so soft and when they wrap their tail around one finger for stability, you can feel how strong those little creatures are.

Before I know it, my shift is over. I check on Rachel one last time (still just fat and not yet a mommy), say goodbye to my boss and go to the changing room to take a shower.

I will see my darlings again tomorrow.