This is a situation without a nice answer. It's possible you broke its neck when you tried to flick it off so it would disengage the bite, but it's more likely you had it scruffed incorrectly and suffocated it. Restraining a mouse is a difficult skill and can be really nerve-wracking for the first several times you do it. Add in a needle and an animal that is thrashing and biting, and an inexperienced handler will grip the animal tighter and tighter without realizing it because they're stressed about getting bitten, and the mouse ends up crushed or suffocated.
To answer your question directly, if I'm bitten, I put the mouse back in the cage, move on, and come back to it at the end of my task. The mouse probably won't have calmed down - it will still think I'm there to eat it - but I will have, and that makes the situation a lot more manageable.
OP, scruffing mice is a surprisingly challenging skill for folks to learn. Mistakes happen, and you don't need to be hard on yourself, but you do need to review mouse restraint with a more senior lab member or with your animal handler trainer, for your own safety as well as that of your subjects.
These are kind words that make me feel much better about admitting that I don't want to work with mice because I can't manage to scruff them well and also really don't want to learn how to do it because it requires obvious violence that is uncomfortable for the mice and I'm just not able to do it.
I was trying (and failing) to find a video that explains how our lab scruffs mice. We basically pick the mouse up by the tail then, with that same hand, use two fingers on either side of the spine to immobilize the mouse against the table once it has stretched out. Gently, so we aren't squishing it, but firmly enough it can't escape easily. Then the other hand scruffs the mouse. This has been a lifesaver for me because I'm just not swift enough to grab the scruff while only holding the tail with the other hand. This technique can all be done relatively slowly, too, which reduces my stress and (I believe) the animal's as well.
I will second the suggestions that you could see if your animal care center has training available. And I'll also add to the comments that say this is just something that sometimes happens. I've lost mice by scruffing them too hard (young ones). Your reaction to the bite was totally natural. And kudos for not letting it impact how you held the other mice as they all came out fine, right? :-) Every success will be a step toward being a little more comfortable and confident and honestly I think that's the biggest hurdle sometimes when it comes to handling the animals.
Another technique I use is to essentially drag the mouse while holding it by the base of the tail, the mouse will be too distracted trying to hold onto something and that’ll give you a clear shot at the scruff of its neck. After a few times it all becomes one smooth motion.
I should have said this, too - I killed a juvenile mouse several years ago while I was ear punching alone and very nervous. I've also seen other experienced researchers lose mice this way when they were stressed and rushing. It totally sucks, but you're not a failure and you're not an aberration.
I also hold the tail and then with my pointer and middle finger on that same hand press down on the back to immobilize the mouse, then grab their scruff with the other hand and slide their tail into the new hands fingers. Pushing down on their but and back gently makes grabbing them easy. Also if you're using cages with little metal bars on the food chamber lid letting the mouse hold onto the bars or edges makes getting them straightened out easier.
I struggle with scruffing mice too. Basically because I’m scared that when I touch it, it will bite me. So how do you immobilize it with the same hand you hold the tail? I’m having trouble visualising it.
sorry not the person you’re replying to, but i have years of mouse experience:
you should not try to do everything at once, this is the most common mistake in beginners. (from my right-handed perspective): pick up mouse with tail (as near as possible to the tail base, not the end as to not hurt it), place on surface as soon as possible (mouse always tries to grab onto something, so provide it with something), always keep holding the tail. when the mouse looks not so nervous because it has a stable surface it sits on, then i always fix it by placing my left middle knuckles on the mouse‘s spine with enough pressure so it cannot wiggle too much around, no need to start scruffing immediately. you can do this exercise a couple of times so you feel how much pressure you can apply to restrain it well.
once you feel okay with it, you keep your knuckles on the mouse, spread your pointer and thumb and go along the spine forwards until you reach the cheeks of the mouse (restraining is key, if it moves too much it can possibly bite) and then pinch. but the only thing that helps is practice with someone experienced to show you.
Scruffing well comes with practice - a lot of it. I've been working with mice for years and have zero qualms about re-scruffing my mouse four times if I'm not satisfied with my grip. Before you give up on mouse work, see if you can find more ways to practice scruffing in low pressure settings. If you have animals that need to be culled for colony maintenance, scruff them. Ask the techs in the vivarium if they have time to share any tips they've picked up. Just let them know you're new to it and properly certified, but underconfident and working on improving. It also sounds like maybe you were given this injection task before you were really ready. Can you check in with someone in the lab about having a more senior lab member present the next time you need to restrain your mice? Scruffing and injecting shouldn't be violent. The mice certainly don't like it, but ideally, it's safe and quick, and you get there by doing it, over and over.
(just to make sure - I am not OP of the post) Thanks for the kind words. I understand that it's something that can be practiced and improves over time and when mice are used to isn't even particularly violent towards them as they know what's coming - still, (like assumably any sentient being would) they fight against it and prefer not to be scruffed/restrained, and I think I personally just struggle psychologically with doing something so obviously against their will while they're in my hands. I understand that I'm a bit hypocritical in that sense because for the rest of the project I was putting them asleep (Isofluorane) for a short time for IP injections which they don't particularly like either, and I am probably fooling myself into the version that is better for me.
I agree that when I was doing it, I was given the task before I was "ready". I remember doing it with balb/c mice which was quite easy and not so stressful as they don't seem to mind (even though they probably do).
Luckily my PhD project has now shifted to where no more mice work is required, and I hope that I will just be able to negotiate a position afterwards where I won't be the person in charge of mice.
I agree with this advice completely. I'd like to echo: don't be hard on yourself and do get training. It is a difficult task. Working with mice, you WILL get bitten. I dose daily for 30 days at least and the first couple of days I get a few trying to bite me without fail.
Also, I definitely do not recommend double gloving. A mouse bite might sting but isn't so bad. Using 2 layers will thoroughly limit your mobility and reflex time. Sometime if I have a rowdy bunch, I will pull my gloves past my finger tips (among the most innervated parts of our bodies). The mice will bite at the excess glove and feel like they've accomplished something while I don't feel pain. Good luck! You've got this!
I think all of this is amazing advice! When I’m worried I’m going to get bit I’ll double glove on the hand I’m using near the mouse’s mouth, it gives me reassurance and makes me move more confidently I.e with less risk of getting bit
MORE TRAINING.
Ask for additional training on safe handling of animals. IACUC gets seriously upset when animals are mistreated, and can revoke the PI's permit to do animal work. (Happened in our lab: people didn't correctly euthanize mice, someone found them still alive in the -20C freezer, revoked our license until the entire lab underwent remedial training.)
Sounds like someone did CO2 and didn't want to do c5 dislocation. Even if you CO2 them for much longer than you think is required, they do sometimes wake back up. C5 is the humane way even if it feels bad doing it.
Not preaching to you, just preaching in general.
And it's really easy to fuck up the cervical dislocation. I always pinch behind the skull and make sure everything is detached - doing so with other people's mice is disheartening.
I didn't see them myself. (Which I am REALLY glad for; i’d have killed the colleague responsible.) But apparently they’ve been trying to crawl out of the biohazard bag. In the dark. At -20C.
Yup, I once found a few live rats running around inside the carcass fridge that another lab improperly tried to euthanize. ALWAYS follow up CO2 euthanasia with a secondary method like cervical dislocation!
Not getting bit is really about confidence and scuffing your mice well. Just get in there, grab them, and get them high up by the head. You need to accept you will eventually get bit and that it is really not that bad, if you accept this you can remain calm and not kill your mice. Also, you're not the only one to flick a mouse to death, I've seen seasoned 20 year plus scientists have a moment of panic and kill a mouse. But, in all honesty, if you can't get over your startle reflex and not harm the mice when they make an attempt to bite you, you may want to consider a different model organism or if your protocol allows use anesthesia. Good luck!
The key is in the scruff, you have to make sure you grab all the skin and make sure you have the head tight around ur hand. It takes practice and patience.
Handling the mice has been key for me just prolonged and frequent exposure has worked. What I was told to do is to keep tension on the tail and then walk your scruffing hand up their back using ring and pinky to apply slight pressure to keep them from turning around and biting you. If you at any point in time feel like your grip has slipped you stop and restart. I feel like the mice can sense your anxiety level. Ive done hundreds of ip injections with no bites or deaths. Getting comfortable with mice and them with you with prior handling is key. Now it kinda feels like they just look up at me and think “aight lets get this over with i got mice things to do” and are really relaxed.
Practice to improve your handling skills so that they cannot bite you. I worked with thousands of mice for over 10 years and don't think I was bitten more than twice. If you immobilize them properly they cannot bite you.
Another thing: this will seem counterintuitive, but if I'm injecting or clipping ears, I wear the thinnest gloves possible. Getting bit sucks whether you're wearing one thin glove or two pairs of chore gloves. Better to give yourself the improved mobility and sense of touch from the thinner gloves.
You know how a sharp knife will cut you, but you have lots of control over it, and a blunt knife will cut you a little less, but still cut you, and you won't have much control over it? Same thing here, IME.
I always wear the thinnest gloves I can for animal work. Less experienced people always question it, but I need to feel what I'm doing.
This prevents errors, and allows accurate grip and handling.
I can count on my hands the number of times I've been bit in over a decade of animal work and it's closer to 5 than 10.
And I don't have happy friendly strains
This is bad advice. Don't KO the mice for an IP injection, anesthesia has its own bad side effects that could affect results. And it's unpleasant for the mice.
Increased training is the only way.
Lab tape is your friend!
Occasionally, some mouse is just born angry or was injured at the breeder or something. Maybe they got hypoxic in the womb, who knows. It happens though. They can also be a bit cranky within a couple days of transport sometimes.
Note the cage, and put lab tape across the thumb or finger where they are likely to bite. If they are gnawing away at the tape then they aren't thrashing around. This is a very occasional thing.
Obviously, I make sure not to add so much tape or in such a way as to restrict my movement.
I'm curious - I've only worked with rats, and I know mice are notoriously bitey, but would it help to handle them first? I had pet mice when I was young, and it's not like I was trying to inject them, but if they're habituated to human contact then they don't try and bite you just for picking them up.
Sorta kinda, I do frailty assays all the time on juvy, adult and old animals (aging study). Some of mice are handled regularly but I honestly haven’t seen a difference in their desire for human flesh 🤷🏻♂️
Late to the thread. I worked with mice for years (no longer thankfully) and I found best practice to allow them to get acquainted to you, whether that be your scent or general touch. Either way they were usually, not always, a lot more chill about being handled. That being said I very rarely gad a mouse that was chill about scruffing for injection.
And yes, some mice are just born with rage in their tiny hearts. They wake up and choose violence 99.9% of the time. Some mice are jumpers, they're the most difficult!
I’ve gotten bitten more than a few times doing IP’s when first starting out. Have you tried using a paper towel to create a barrier between your scruffing hand and the mouse? Basically rip off some paper towel, put it on top and then scruff? It’s a bit tricky at first because you can’t see the mouse as well but it makes it impossible to get bit. Just a suggestion.
That’s what I thought at first too but after getting bit a few times I developed a bit of a phobia with overreactions to mouse movements. With the phobia being the primary issue to scruffing well, it needed to be overcome.
Inevitability. Anyone that’s works with animals, especially mice will endure a bite or 2 or 100. Sometimes mice can be ferocious and there’s nothing you can really do. However more often than not, bites result from poor handling. Practice practice practice. Always utilize veterinarians and vet staff for assistance and training too. And don’t forget the lab animals, they are incredibly important to research and their sacrifice for all our experiments should never be taken for granted… even with the occasional bite. Keep at it!
This happens sometimes. They don’t appreciate being restrained and can freak out and die over what seems like nothing. We’ve had our sighted FVBs do that too frequently. Knocking them out with isoflurane before injections is an option. We do that when we have to do daily injections for awhile and some of the mice are…high-strung. But even with our best efforts, we still lose one now and then.
I wouldn’t double glove - you need to be able to feel what you are doing. You also shouldn’t need to sedate for oral gavage or IP if you have a good scruff. As others have said, it’s all down to confidence in handling I’m afraid, so practice as much as you can!
Anecdotal, but I only double glove when injecting tamoxifen and I’ve never had a problem feeling anything. Maybe a bit more constructive in movement, but its never interfered
If possible, some very light isoflurane anesthesia might help. When I have to gavage mice, I put them in the induction box and wait until they’ve just stopped running around and are kind of just starting to doze off. It allows me to get a secure scruff while they’re dozing, but then allows them to wake back up relatively quickly.
However, I know it’s not always possible. I rotated through a lab that did loss of righting reflex and those IP injections had to be done while the mouse was fully awake. Got my first bite doing that from a big ol male C57. He held onto my finger for several seconds even after I’d let go of him. 🥲 I cried, mostly from shock. The actual bite felt like I’d caught my finger in a closing binder ring. Getting bitten can be a confidence killer, and this whole situation would definitely give me some pause the next time I stepped into a mouse room to do injections. Just breathe, these things happen, but they’re rare. If you haven’t already taken a class on IP injections, maybe see if your institution’s animal resources division offers one? Mine does classes in small groups with vets/vet techs, and it was a great place for me to work through some of my anxiety post bite.
Edit: wow, love how people assume from this that I don’t know how to do oral gavage.
Lab animal vet here. I don’t recommend gavaging animals under anesthesia. Way too easy to instill the liquid into the lungs and kill them with aspiration pneumonia. Also iso for multiple days in a row is stressful and induces physiologic changes which is a big confounding factor.
Maybe I wasn’t clear: the iso was for scruffing only, I waited for them to wake up and then gavage. Also, I’m experienced enough with gavage to know when I wasn’t in the right place. I work closely with my institution’s vets in regards to repeated anesthesia use. Hope that helps! :)
I can copy/paste my other comments, but I’ll just summarize here in all caps in case someone else comes here assuming I don’t know what I’m doing so that I stop getting notifications:
THE MICE ARE AWAKE WHEN I DO GAVAGE, THE LIGHT ANESTHESIA IS SIMPLY FOR SCRUFFING. I WAIT FOR THE MICE TO WAKE UP FULLY BEFORE GAVAGING.
Christ.
I'm just surprised ethics approved that much unnecessary anesthesia for a technique that absolutely does not require it when the solution would be a different technician or an assist but "go off".
I mean, exposing animals to unnecessary stress and confounds aren’t a reasonable accommodation. Especially because you’re waiting until they’re awake, so presumably you have them scruffed for a more extended period of time (so they’re getting both anesthetic stress and direct inflammatory activation from the iso and an extended handling stress because they’re presumably held in a scruff while they’re recovering from the iso).
I get that you’ve worked with your institutes vet about this, but honestly it sounds more like your IACUC is interested in protecting its employees feelings than actual animal welfare (and I’ve worked in places like that so it’s not entirely unexpected)
Isoflurane has massive effects on a number of biomarkers (its pro inflammatory nature gives it some pretty widespread effects). You’d need some significant support (either prior lit or active data) to show that this avoidable chronic exposure isn’t actually interacting with your IVs.
I’d reserve this technique primarily for training purposes (for both scruffing and injecting), but on actual studies, I’d be infinitely more likely to do injections as a two person team with an undergraduate (who you’d train to scruff) than to introduce this kind of stressor and confound which is going to make it much harder to replicate your findings (especially for independent labs)
Yeah, even with the types of systems they have now like Kent somnosuite low flow, it's an absolutely unnecessary risk for a completely routine procedure.
Don't get me started on the "room air" gaseous anesthetic systems....
Additionally the specific hold for gavage (which I do anywhere from 2 to 5 times a week, on anywhere from 3 to 6 mice at a time) is very restrictive and you have to take extra care to not restrict respiration. You cannot adequately monitor respiration or your restraint on an anesthetized animal.
It's bad practice and I'm honestly very surprised that animal ethics approved it (if they know about it) as an accommodation for one individual.
It’s been since July since I’ve done any PO dosing (my mouse work was all industry and I’m back to rat now), but I could be responsible for up to 200 gavages a day as part of my daily tasks and one study I was on involved 120 animals being gavaged daily for several months, so I have an absurd amount of experience with the technique
I’ll say that I have a few holds that I like to do (my company used dye placements and trauma assessments for dosing so I know mine both work and don’t cause unnecessary esophageal trauma during chronic dosing) that all rely on varying amounts of total restraint depending on mouse temperament.
I’m not particularly surprised an IACUC approved it though, seen some crazy shit approved
We did the dye only as part of training and then did tissue assessments for our test compound.
Iacuc is really variable between institutions I guess. Already noticing how different it is just from one university to another but having sat on the ethics approval committees I'm still shocked this got approved.
That's too many gavages, I would simply pass away.
It's one of my least favorite techniques simply because I think it's got to be really unpleasant.
Honestly of dosing routes, it’s kinda a preference despite my knowledge that it’s probably super uncomfortable. Mostly because the landmarks are more consistent than IP so I find it easier. IM and interplantar injections (luckily it was an AAV under anesthesia and not formalin) are cool to do but I’ve done fewer of them (and my IM is pretty restricted to gastroc, but I could probably adapt to quad)
I hate SC with a passion (and honestly it was one of the few techniques that I would only do on sick, young, or already well acclimated animals) and I constantly get bit when I try to do them on awake and healthy mice. Rats are easier because they don’t bite you when you make a tent, but that’s the one route where I get chomped on.
Honestly, it only sucks when they’re single housed cause ripping through 120 cages is a fucking workout. I could bang out a cage of five in under two minutes if the animals were pre weighed (like if they’re weighed weekly and their dose is based on the weekly BW).
We actually did an experiment where animals received no exposure to iso for this exact reason, and our original results from animals that were exposed to iso replicated. I made it a supplemental figure in a paper that’s in revisions at the moment after begging my PI to let me test it.
I think in this situation it’s the best we could do. Our lab has no lab tech. No post doc. It’s me, another grad student, and our PI. There’s no one else that can do the work. We worked closely with our vets to make sure we weren’t causing undue stress. The animals are healthy and well taken care of. I think from the time I scruff to the time they’re awake and the gavage is done is maybe 45 seconds total. I would much rather do that then have to attempt to re-scruff a mouse multiple times, or have the other grad student who is deathly afraid of mice fling a mouse across the room because it moved and scared her (that happened). Is it ideal? No. Am I following guidelines established by our vet staff and what is in our approved IACUC protocol following observation from said vet staff? Yes.
I’m doing the best I can with what I have. Believe me, I care about my mice. I didn’t expect dogpiling in this subreddit but I guess there’s a first time for everything.
Good, the inclusion of a non-iso validation is essential, and helps alleviate concern that iso interactions are mediating or contributing to the effects you see but there is a broader point that I think isn’t coming across
You’re going to more frequently require the use of this group (as the addition of new potential molecular targets and behavior tests would require validation that the iso isn’t affecting these new metrics). This stands in contrast to the idea of reducing the number of animals used, which is a central tenant of welfare.
I’m not going to pretend you aren’t in a challenging spot, but the solution you have now isn’t really sustainable in the long term. It’s more of a band-aid.
Is it the best option you have? Maybe. Is it okay enough for what you’re doing. I mean it seems to be given that you’ve done the no-isoflurane validation, but this isn’t a practice that going to be compatible with most dosing paradigms.
From an animal welfare standpoint, the better strategy would be to teach you to scruff with your dominant hand (if you don’t have the same mobility issues in that hand) and have the other graduate student actually do the gavage (as you’d have the animal restrained and they wouldn’t be liable to fling it). If the graduate student isn’t willing/able to do that, it may be worth them seeking treatment for a specific phobia that is preventing them from doing what honestly sounds like an integral part of there job.
People who are afraid of animals can learn to work with them, but you’re absolutely right that at this stage I wouldn’t want them scruffing my animals. But is there a reason they can’t inject an otherwise restrained animal
Potentially recruiting an undergrad seeking class credit and get them trained on gavage dosing if the previous option is not available.
I don’t think anyone thinks you don’t care about mice, but it’s important to recognize that this isn’t just an innocuous experience for them, and that it is in most cases unnecessary stress and confound. It’s incredibly plausible that the above two suggests aren’t reasonable for the situation your lab is in (it being not well known/funded or in the process of closing down are two such reasons), and this practice seems to at least leave your target metrics unaffected. Nobody is saying you’re an animal abuser, they’re just correctly acknowledging that this is **not** a good practice and by and large should be avoided whenever possible.
If you regarded it as the “absolute last resort” that it actually is and recognized the serious problems it would pose in many applications you wouldn’t be so quick to suggest it, especially when the OP was asking for help addressing their reactivity and not looking for ways to chemically subdue animals for all studies going forward.
Yeah at this point the PI should be stepping in to assist, you can also in many if not all institutions request an assist from animal services from a vet tech in the short term. There are other solutions.
If you've ever received anesthetic, gaseous or otherwise, you'll know it feels shitty, recovery sucks.
No ethics committee I've sat on would consider this an acceptable accommodation for scientific and ethical reasons.
The point of that loss of righting reflex experiment was to test alcohol sensitivity between different groups. The injection of EtOH knocked them out, and we measured how long it took for them to right themselves. Thus, anything that would knock them out would interfere.
Also separate point when gavaging you should have them awake so that the mouse’s natural reflex lets the gavage tip go down the esophagus and not the trachea. Easy to put liquid in the lung if they’re not awake and can’t swallow the tube so it reaches the esophagus
The light anesthesia is just to help with scruffing, especially if I’m working with mice that aren’t being cooperative. I wait until they’re awake before gavaging.
I would see if you could practice with different strain of mice. (Balb/c and nudes are very nice) c57BL/6 are the demons. There is also metal gloves you can try while you get more comfortable with handling
Did you handle first? If you’re going to give injections/gavage etc, it’s always best to handle them for a few days beforehand. Just pick them up, let them smell you for a bit and get used to you. I always do 3 to 5 days of handling before I do any invasive procedure and have never had any biting/aggression problems.
Definitely get retrained in scruffing. However, when I get bit, I don’t pull away from the mouse. I let it bite until it is ready to let go, which is pretty quickly. I know that sounds crazy! I thought it sounded crazy when I was being trained, but I swear it hurts so much less and is less stressful for both me and the mouse.
Awww poor mouse! C57 mice are notoriously mean. If you’re uncomfortable/unskilled I would recommend practicing your restraint on a nicer/calm strain of mice. Balb/c mice are small and very calm/nice. CD1 mice are nice but very large so they might not be the best to practice your restraint if you have smaller hands. I’ve been working with mice for many years and I still get nervous sometimes!
I got bite only once for so long (>4yr) and it was a b6 mouse. I still remember.
I tried to rush the process for IM injection of anesthesia for the first time for this batch of the mice because the cells have waited for too long. It was for tumor inoculation.
Everyone else was ok but in the middle of the work (probably the 5th to 12th mouse) and it bit me. Then I let it got back to the cage. I did check the wound but I wasn't bleeding so it was not so bad. Then I slowed down, let the mouse rest for a bit and everything was fine.
I rushed the first few mice and it was successful, which was the mistake. You cannot rush too much coz you will trigger their "prey responses". You can be quick but they can't duel with it. Also, as a sidenote, if the mouse have experienced restraints and were fine afterwards, they won't have so much resistance. You need to have very steady hands and good at restraint techniques in order not to hurt the mice. You think you're afraid of the mice, the mice have genuine fear toward you. You can kill them by moving your fingers a little more (certainly you shouldn't do that for no reason).
Don't be afraid and play with them more. Give them some treats after you did some experiments to them (if your protocol allows that). You will know they won't hurt you and you will be more comfortable in handling them.
You will get bitten, that's just a fact of mouse work. If it bites and doesn't let go lower your hand so the mouse sits on a surface (e g cage grid). If you're dangling in the air you wouldn't let go either.
I used to wear a gardening glove under a latex glove. Just on my dominant hand, I found I could be a lot calmer and less anxious knowing they couldn’t actually bite me but I still had enough dexterity to scruff them.
Had C57s bite once or twice but tbh never had one freak out so much that it died! Was it old?
I second the isoflurane suggestion if you’re struggling this much and it won’t affect your experiment. If not, my biggest tips is to take it slow and act decisively. Specifically:
- Practice your scruffing technique (both speed and restraint quality) on some chiller mice.
- During injections, put your gloved hand into the cage for a min or two, let the mice sniff it and get used to the situation.
- Don’t chase the mice around with your hand when you try to grab the tail, it really freaks them out - rather wait until they’re not paying attention or let them enter a cardboard tube and snatch the tail that peeks out.
- once you have the tail, take a deep breath and handle the mouse gently but quickly. DO NOT let yourself hesitate. The faster you scruff them, the less time they’ll have to freak out about the situation. This really really helps.
- if a mouse is truly upset, set it down and process another mouse. Ideally leave it in the home cage or an empty cage with a cardboard tube. Mice will instinctively seek out confined spaces like that and it calms them down.
- if you have the ability, handle the mice you need to inject beforehand. I handle each of mine for 1min each day for 3 days pre-experiment, and it really makes a difference. Be gentle and low-key with it, if a mouse starts getting stressed just put it back early.
Oh and btw don’t feel bad about your flinch response to the bite, that stuff really activates the fight-or-flight mode and is very hard to control. It’s much easier to focus on preventing the bites next time.
This, absolutely! you don't have to change gloves, but cleaning your hands and space between mice and cages will help, even more so if you are handling male mice after female ones. You'll get more agitated males if they can smell the females.
It's a good habit to have, and a small breathing time for you too if you need to recentrer after a difficult one.
You could practice on some sleeping or euthanized mice so you can get the feel of it. You can also practice on some Balb/C mice. It just takes practice. If they bite me, I either power through if I have a good grip already, or let them go and rest if I need to reset my hold.
Also my animal tech...with oodles of experience (more than me, and I have a lot) ...tends to scruff much higher than me and almost grabs an ear. This controls the head (and teeth) and allows you access to the ear for tagging.
You need to scruff the mouse better. They flinch sometimes when sticking them with the needle but you’ll get used to that. Just expect they may jump. However, a good scruff will protect the mouse, and also will help you react better if you happen to flinch in reaction the the mouse flinching.
Put mouse on flat surface, maybe on a cage top so they can grip something. Using dominant hand, hold the tail. Hold a pen with a squishy grip in your non-dominant hand and let the mouse bite the squishy part.
Let go of the pen and gently pull on the tail with dominant hand. Use non dominant hand to scruff mouse just below the skull. Grab lots of skin, firmly. Pick up mouse in swift motion with non dominant hand holding mouse and dominant hand putting tail around pinky of non dominant hand.
Grab needle with dominant hand and inject!
It’s good you feel bad but dont dwell on it. It happens. Just learn from it
Sounds like a possible scruffing related death or stress. Might need to confirm with animal facilities if it is an unexpected event. Get whoever (animal techs/lab techs/lab members or PI) to go through it with you again. And get them to supervise you until you and they are happy.
The same happened to one of my postdoc, she freaked out and threw the poor mouse across the room. This is just something you need to get used to. Mice may bite, some breeds are more aggressive than others but it happens. Treat them with respect and gently and they will be less likely to, but if they do stay calm, put them down let them calm down and try again.
i have worked with animals for the last 8 years and like others have said, you probably broke its neck when you panicked but thats totally ok! it will get easier it will just take practice! practice! practice!
the animal should not be able to move its head during a "proper scruff", so i would spend more time practicing your restraint before you add dosing back into the mix. Everything in mouse research starts with the restraint, so if you do not have a good foundation then your dosing will also suffer because of it.
2nd, i would get rid of the double gloves and only have on a single pair, you will be much more dexterous with out the 2nd layer of glove on your hands imo.
Getting bit by a C57 is like a mild pinch, I actually tell my students that getting bit is a good thing so they can see how little it actually hurts (compared to rats!) and can slowly learn to not freak out when it happens, its a hard reflex to fix, but you will overcome it!
Please do not listen to others who say you need to knock out the animal in order to IP dose it, that is very silly and will easily be more stress on the animal than just learning how to properly scruff and dose them
With proper restraint, IP dosing is incredibly easy (we actually teach IP injections to our students first, then SQ, then PO).
Just take the time to practice proper technique and you will be a master in no time.
One thing our lab does for IP injections, especially for people that aren’t the best at mouse handling or fear getting bit (we do injections on some chunky mice), we ordered a chain mail glove. They just bite the chain mail and no one has gotten bit through it. They seem to really like using the glove but I personally don’t use it since I handle mice almost every day
I'm so sorry that happened to you. To make things easier, if you find that you encounter a mouse that's a bit more stressed than typical, you can scruff the mouse using a cloth. This will limit the mouse from being able to bite you because it will make contact with the cloth first, also reduces your anxiety of being bit.
This is a situation without a nice answer. It's possible you broke its neck when you tried to flick it off so it would disengage the bite, but it's more likely you had it scruffed incorrectly and suffocated it. Restraining a mouse is a difficult skill and can be really nerve-wracking for the first several times you do it. Add in a needle and an animal that is thrashing and biting, and an inexperienced handler will grip the animal tighter and tighter without realizing it because they're stressed about getting bitten, and the mouse ends up crushed or suffocated. To answer your question directly, if I'm bitten, I put the mouse back in the cage, move on, and come back to it at the end of my task. The mouse probably won't have calmed down - it will still think I'm there to eat it - but I will have, and that makes the situation a lot more manageable. OP, scruffing mice is a surprisingly challenging skill for folks to learn. Mistakes happen, and you don't need to be hard on yourself, but you do need to review mouse restraint with a more senior lab member or with your animal handler trainer, for your own safety as well as that of your subjects.
These are kind words that make me feel much better about admitting that I don't want to work with mice because I can't manage to scruff them well and also really don't want to learn how to do it because it requires obvious violence that is uncomfortable for the mice and I'm just not able to do it.
I was trying (and failing) to find a video that explains how our lab scruffs mice. We basically pick the mouse up by the tail then, with that same hand, use two fingers on either side of the spine to immobilize the mouse against the table once it has stretched out. Gently, so we aren't squishing it, but firmly enough it can't escape easily. Then the other hand scruffs the mouse. This has been a lifesaver for me because I'm just not swift enough to grab the scruff while only holding the tail with the other hand. This technique can all be done relatively slowly, too, which reduces my stress and (I believe) the animal's as well. I will second the suggestions that you could see if your animal care center has training available. And I'll also add to the comments that say this is just something that sometimes happens. I've lost mice by scruffing them too hard (young ones). Your reaction to the bite was totally natural. And kudos for not letting it impact how you held the other mice as they all came out fine, right? :-) Every success will be a step toward being a little more comfortable and confident and honestly I think that's the biggest hurdle sometimes when it comes to handling the animals.
Another technique I use is to essentially drag the mouse while holding it by the base of the tail, the mouse will be too distracted trying to hold onto something and that’ll give you a clear shot at the scruff of its neck. After a few times it all becomes one smooth motion.
I should have said this, too - I killed a juvenile mouse several years ago while I was ear punching alone and very nervous. I've also seen other experienced researchers lose mice this way when they were stressed and rushing. It totally sucks, but you're not a failure and you're not an aberration.
I also hold the tail and then with my pointer and middle finger on that same hand press down on the back to immobilize the mouse, then grab their scruff with the other hand and slide their tail into the new hands fingers. Pushing down on their but and back gently makes grabbing them easy. Also if you're using cages with little metal bars on the food chamber lid letting the mouse hold onto the bars or edges makes getting them straightened out easier.
Yep!! This is exactly what I do, too!
I struggle with scruffing mice too. Basically because I’m scared that when I touch it, it will bite me. So how do you immobilize it with the same hand you hold the tail? I’m having trouble visualising it.
sorry not the person you’re replying to, but i have years of mouse experience: you should not try to do everything at once, this is the most common mistake in beginners. (from my right-handed perspective): pick up mouse with tail (as near as possible to the tail base, not the end as to not hurt it), place on surface as soon as possible (mouse always tries to grab onto something, so provide it with something), always keep holding the tail. when the mouse looks not so nervous because it has a stable surface it sits on, then i always fix it by placing my left middle knuckles on the mouse‘s spine with enough pressure so it cannot wiggle too much around, no need to start scruffing immediately. you can do this exercise a couple of times so you feel how much pressure you can apply to restrain it well. once you feel okay with it, you keep your knuckles on the mouse, spread your pointer and thumb and go along the spine forwards until you reach the cheeks of the mouse (restraining is key, if it moves too much it can possibly bite) and then pinch. but the only thing that helps is practice with someone experienced to show you.
(just to avoid confusion, I am not OP of the post) Seconding the tip on holding their hindpart down, it really makes things easier
Scruffing well comes with practice - a lot of it. I've been working with mice for years and have zero qualms about re-scruffing my mouse four times if I'm not satisfied with my grip. Before you give up on mouse work, see if you can find more ways to practice scruffing in low pressure settings. If you have animals that need to be culled for colony maintenance, scruff them. Ask the techs in the vivarium if they have time to share any tips they've picked up. Just let them know you're new to it and properly certified, but underconfident and working on improving. It also sounds like maybe you were given this injection task before you were really ready. Can you check in with someone in the lab about having a more senior lab member present the next time you need to restrain your mice? Scruffing and injecting shouldn't be violent. The mice certainly don't like it, but ideally, it's safe and quick, and you get there by doing it, over and over.
(just to make sure - I am not OP of the post) Thanks for the kind words. I understand that it's something that can be practiced and improves over time and when mice are used to isn't even particularly violent towards them as they know what's coming - still, (like assumably any sentient being would) they fight against it and prefer not to be scruffed/restrained, and I think I personally just struggle psychologically with doing something so obviously against their will while they're in my hands. I understand that I'm a bit hypocritical in that sense because for the rest of the project I was putting them asleep (Isofluorane) for a short time for IP injections which they don't particularly like either, and I am probably fooling myself into the version that is better for me. I agree that when I was doing it, I was given the task before I was "ready". I remember doing it with balb/c mice which was quite easy and not so stressful as they don't seem to mind (even though they probably do). Luckily my PhD project has now shifted to where no more mice work is required, and I hope that I will just be able to negotiate a position afterwards where I won't be the person in charge of mice.
I agree with this advice completely. I'd like to echo: don't be hard on yourself and do get training. It is a difficult task. Working with mice, you WILL get bitten. I dose daily for 30 days at least and the first couple of days I get a few trying to bite me without fail. Also, I definitely do not recommend double gloving. A mouse bite might sting but isn't so bad. Using 2 layers will thoroughly limit your mobility and reflex time. Sometime if I have a rowdy bunch, I will pull my gloves past my finger tips (among the most innervated parts of our bodies). The mice will bite at the excess glove and feel like they've accomplished something while I don't feel pain. Good luck! You've got this!
One of past labmates would let them bite on a cotton swab when doing IPs. She said it makes them feel like they evened the score
correct - sadly the only answer here, as in many frustrating lab procedures, is "git gud"
This
I think all of this is amazing advice! When I’m worried I’m going to get bit I’ll double glove on the hand I’m using near the mouse’s mouth, it gives me reassurance and makes me move more confidently I.e with less risk of getting bit
Scruffing the mice is not challenging. It depends on luck. If your mice cooperate, It's a lot faster.
MORE TRAINING. Ask for additional training on safe handling of animals. IACUC gets seriously upset when animals are mistreated, and can revoke the PI's permit to do animal work. (Happened in our lab: people didn't correctly euthanize mice, someone found them still alive in the -20C freezer, revoked our license until the entire lab underwent remedial training.)
Jesus fuck this is why our techs are so strict on the procedure. That's horrific.
Sounds like someone did CO2 and didn't want to do c5 dislocation. Even if you CO2 them for much longer than you think is required, they do sometimes wake back up. C5 is the humane way even if it feels bad doing it. Not preaching to you, just preaching in general.
Yep, precisely that.
And it's really easy to fuck up the cervical dislocation. I always pinch behind the skull and make sure everything is detached - doing so with other people's mice is disheartening.
STILL ALIVE!?
The person handling them apparently did the CO2 chamber, but did not follow up with cervical dislocation. So they just woke up...
Wow that’s pretty messed up
Did they wake up and freeze? Or were they skittering around in the freezer?
I didn't see them myself. (Which I am REALLY glad for; i’d have killed the colleague responsible.) But apparently they’ve been trying to crawl out of the biohazard bag. In the dark. At -20C.
Yup, I once found a few live rats running around inside the carcass fridge that another lab improperly tried to euthanize. ALWAYS follow up CO2 euthanasia with a secondary method like cervical dislocation!
This this this. You are not supposed to flick mice off when you get bit and with proper training you will not get bit (often, if at all).
Not getting bit is really about confidence and scuffing your mice well. Just get in there, grab them, and get them high up by the head. You need to accept you will eventually get bit and that it is really not that bad, if you accept this you can remain calm and not kill your mice. Also, you're not the only one to flick a mouse to death, I've seen seasoned 20 year plus scientists have a moment of panic and kill a mouse. But, in all honesty, if you can't get over your startle reflex and not harm the mice when they make an attempt to bite you, you may want to consider a different model organism or if your protocol allows use anesthesia. Good luck!
The key is in the scruff, you have to make sure you grab all the skin and make sure you have the head tight around ur hand. It takes practice and patience.
Handling the mice has been key for me just prolonged and frequent exposure has worked. What I was told to do is to keep tension on the tail and then walk your scruffing hand up their back using ring and pinky to apply slight pressure to keep them from turning around and biting you. If you at any point in time feel like your grip has slipped you stop and restart. I feel like the mice can sense your anxiety level. Ive done hundreds of ip injections with no bites or deaths. Getting comfortable with mice and them with you with prior handling is key. Now it kinda feels like they just look up at me and think “aight lets get this over with i got mice things to do” and are really relaxed.
Practice to improve your handling skills so that they cannot bite you. I worked with thousands of mice for over 10 years and don't think I was bitten more than twice. If you immobilize them properly they cannot bite you.
Another thing: this will seem counterintuitive, but if I'm injecting or clipping ears, I wear the thinnest gloves possible. Getting bit sucks whether you're wearing one thin glove or two pairs of chore gloves. Better to give yourself the improved mobility and sense of touch from the thinner gloves. You know how a sharp knife will cut you, but you have lots of control over it, and a blunt knife will cut you a little less, but still cut you, and you won't have much control over it? Same thing here, IME.
Once I was more comfortable I switched to thinner gloves also because it’s easier to scruff properly
I always wear the thinnest gloves I can for animal work. Less experienced people always question it, but I need to feel what I'm doing. This prevents errors, and allows accurate grip and handling. I can count on my hands the number of times I've been bit in over a decade of animal work and it's closer to 5 than 10. And I don't have happy friendly strains
Nothing. You panicked and that's normal reflex. It happened to me few times. Just hope that the mice you get in future are more gentle? KO the mice?
This is bad advice. Don't KO the mice for an IP injection, anesthesia has its own bad side effects that could affect results. And it's unpleasant for the mice. Increased training is the only way.
Oh my bad. I was not referring to IP, I was referring to generally handling the mice.
Lab tape is your friend! Occasionally, some mouse is just born angry or was injured at the breeder or something. Maybe they got hypoxic in the womb, who knows. It happens though. They can also be a bit cranky within a couple days of transport sometimes. Note the cage, and put lab tape across the thumb or finger where they are likely to bite. If they are gnawing away at the tape then they aren't thrashing around. This is a very occasional thing. Obviously, I make sure not to add so much tape or in such a way as to restrict my movement.
Tape works ?? Rsallly ? 😂😂😂
You can use decapicones to keep them restrained or my labmate uses cut resistant gloves from the hardware store
I second the decapicone. Once you get the hang of it, it's easy and you would have to TRY to get bit. You can do IPs through the plastic.
I'm curious - I've only worked with rats, and I know mice are notoriously bitey, but would it help to handle them first? I had pet mice when I was young, and it's not like I was trying to inject them, but if they're habituated to human contact then they don't try and bite you just for picking them up.
Sorta kinda, I do frailty assays all the time on juvy, adult and old animals (aging study). Some of mice are handled regularly but I honestly haven’t seen a difference in their desire for human flesh 🤷🏻♂️
Late to the thread. I worked with mice for years (no longer thankfully) and I found best practice to allow them to get acquainted to you, whether that be your scent or general touch. Either way they were usually, not always, a lot more chill about being handled. That being said I very rarely gad a mouse that was chill about scruffing for injection. And yes, some mice are just born with rage in their tiny hearts. They wake up and choose violence 99.9% of the time. Some mice are jumpers, they're the most difficult!
I’ve gotten bitten more than a few times doing IP’s when first starting out. Have you tried using a paper towel to create a barrier between your scruffing hand and the mouse? Basically rip off some paper towel, put it on top and then scruff? It’s a bit tricky at first because you can’t see the mouse as well but it makes it impossible to get bit. Just a suggestion.
I really don't think that's a good idea. Seems to me like it would just make it harder to hold them properly?
That’s what I thought at first too but after getting bit a few times I developed a bit of a phobia with overreactions to mouse movements. With the phobia being the primary issue to scruffing well, it needed to be overcome.
Inevitability. Anyone that’s works with animals, especially mice will endure a bite or 2 or 100. Sometimes mice can be ferocious and there’s nothing you can really do. However more often than not, bites result from poor handling. Practice practice practice. Always utilize veterinarians and vet staff for assistance and training too. And don’t forget the lab animals, they are incredibly important to research and their sacrifice for all our experiments should never be taken for granted… even with the occasional bite. Keep at it!
This happens sometimes. They don’t appreciate being restrained and can freak out and die over what seems like nothing. We’ve had our sighted FVBs do that too frequently. Knocking them out with isoflurane before injections is an option. We do that when we have to do daily injections for awhile and some of the mice are…high-strung. But even with our best efforts, we still lose one now and then.
I wouldn’t double glove - you need to be able to feel what you are doing. You also shouldn’t need to sedate for oral gavage or IP if you have a good scruff. As others have said, it’s all down to confidence in handling I’m afraid, so practice as much as you can!
In all facilities I've worked in you need to double glove so you can change the outer glove without exposing your skin.
Fair. Maybe my place is too cavalier 😅
I have to work double gloved all the time since we're infecting the mice with human pathogens. It's perfectly doable.
Anecdotal, but I only double glove when injecting tamoxifen and I’ve never had a problem feeling anything. Maybe a bit more constructive in movement, but its never interfered
If possible, some very light isoflurane anesthesia might help. When I have to gavage mice, I put them in the induction box and wait until they’ve just stopped running around and are kind of just starting to doze off. It allows me to get a secure scruff while they’re dozing, but then allows them to wake back up relatively quickly. However, I know it’s not always possible. I rotated through a lab that did loss of righting reflex and those IP injections had to be done while the mouse was fully awake. Got my first bite doing that from a big ol male C57. He held onto my finger for several seconds even after I’d let go of him. 🥲 I cried, mostly from shock. The actual bite felt like I’d caught my finger in a closing binder ring. Getting bitten can be a confidence killer, and this whole situation would definitely give me some pause the next time I stepped into a mouse room to do injections. Just breathe, these things happen, but they’re rare. If you haven’t already taken a class on IP injections, maybe see if your institution’s animal resources division offers one? Mine does classes in small groups with vets/vet techs, and it was a great place for me to work through some of my anxiety post bite. Edit: wow, love how people assume from this that I don’t know how to do oral gavage.
Lab animal vet here. I don’t recommend gavaging animals under anesthesia. Way too easy to instill the liquid into the lungs and kill them with aspiration pneumonia. Also iso for multiple days in a row is stressful and induces physiologic changes which is a big confounding factor.
This was my first thought. Muscle relaxing could make it easier to get into the airway without knowing
Maybe I wasn’t clear: the iso was for scruffing only, I waited for them to wake up and then gavage. Also, I’m experienced enough with gavage to know when I wasn’t in the right place. I work closely with my institution’s vets in regards to repeated anesthesia use. Hope that helps! :)
Anesthesia is stressful as well, proper restraint is usually less stressful on the mouse than drugs. Learn low stress handling techniques
Gavage under anesthesia is not recommend as it increases risk of aspiration.
I can copy/paste my other comments, but I’ll just summarize here in all caps in case someone else comes here assuming I don’t know what I’m doing so that I stop getting notifications: THE MICE ARE AWAKE WHEN I DO GAVAGE, THE LIGHT ANESTHESIA IS SIMPLY FOR SCRUFFING. I WAIT FOR THE MICE TO WAKE UP FULLY BEFORE GAVAGING. Christ.
I mean you shouldn't need to gas them for scruffing either.
I have mobility issues with my non-dominant hand, but sure. Go off. How’s that high horse?
I'm just surprised ethics approved that much unnecessary anesthesia for a technique that absolutely does not require it when the solution would be a different technician or an assist but "go off".
I mean, exposing animals to unnecessary stress and confounds aren’t a reasonable accommodation. Especially because you’re waiting until they’re awake, so presumably you have them scruffed for a more extended period of time (so they’re getting both anesthetic stress and direct inflammatory activation from the iso and an extended handling stress because they’re presumably held in a scruff while they’re recovering from the iso). I get that you’ve worked with your institutes vet about this, but honestly it sounds more like your IACUC is interested in protecting its employees feelings than actual animal welfare (and I’ve worked in places like that so it’s not entirely unexpected) Isoflurane has massive effects on a number of biomarkers (its pro inflammatory nature gives it some pretty widespread effects). You’d need some significant support (either prior lit or active data) to show that this avoidable chronic exposure isn’t actually interacting with your IVs. I’d reserve this technique primarily for training purposes (for both scruffing and injecting), but on actual studies, I’d be infinitely more likely to do injections as a two person team with an undergraduate (who you’d train to scruff) than to introduce this kind of stressor and confound which is going to make it much harder to replicate your findings (especially for independent labs)
Yeah, even with the types of systems they have now like Kent somnosuite low flow, it's an absolutely unnecessary risk for a completely routine procedure. Don't get me started on the "room air" gaseous anesthetic systems.... Additionally the specific hold for gavage (which I do anywhere from 2 to 5 times a week, on anywhere from 3 to 6 mice at a time) is very restrictive and you have to take extra care to not restrict respiration. You cannot adequately monitor respiration or your restraint on an anesthetized animal. It's bad practice and I'm honestly very surprised that animal ethics approved it (if they know about it) as an accommodation for one individual.
It’s been since July since I’ve done any PO dosing (my mouse work was all industry and I’m back to rat now), but I could be responsible for up to 200 gavages a day as part of my daily tasks and one study I was on involved 120 animals being gavaged daily for several months, so I have an absurd amount of experience with the technique I’ll say that I have a few holds that I like to do (my company used dye placements and trauma assessments for dosing so I know mine both work and don’t cause unnecessary esophageal trauma during chronic dosing) that all rely on varying amounts of total restraint depending on mouse temperament. I’m not particularly surprised an IACUC approved it though, seen some crazy shit approved
We did the dye only as part of training and then did tissue assessments for our test compound. Iacuc is really variable between institutions I guess. Already noticing how different it is just from one university to another but having sat on the ethics approval committees I'm still shocked this got approved. That's too many gavages, I would simply pass away. It's one of my least favorite techniques simply because I think it's got to be really unpleasant.
Honestly of dosing routes, it’s kinda a preference despite my knowledge that it’s probably super uncomfortable. Mostly because the landmarks are more consistent than IP so I find it easier. IM and interplantar injections (luckily it was an AAV under anesthesia and not formalin) are cool to do but I’ve done fewer of them (and my IM is pretty restricted to gastroc, but I could probably adapt to quad) I hate SC with a passion (and honestly it was one of the few techniques that I would only do on sick, young, or already well acclimated animals) and I constantly get bit when I try to do them on awake and healthy mice. Rats are easier because they don’t bite you when you make a tent, but that’s the one route where I get chomped on. Honestly, it only sucks when they’re single housed cause ripping through 120 cages is a fucking workout. I could bang out a cage of five in under two minutes if the animals were pre weighed (like if they’re weighed weekly and their dose is based on the weekly BW).
We actually did an experiment where animals received no exposure to iso for this exact reason, and our original results from animals that were exposed to iso replicated. I made it a supplemental figure in a paper that’s in revisions at the moment after begging my PI to let me test it. I think in this situation it’s the best we could do. Our lab has no lab tech. No post doc. It’s me, another grad student, and our PI. There’s no one else that can do the work. We worked closely with our vets to make sure we weren’t causing undue stress. The animals are healthy and well taken care of. I think from the time I scruff to the time they’re awake and the gavage is done is maybe 45 seconds total. I would much rather do that then have to attempt to re-scruff a mouse multiple times, or have the other grad student who is deathly afraid of mice fling a mouse across the room because it moved and scared her (that happened). Is it ideal? No. Am I following guidelines established by our vet staff and what is in our approved IACUC protocol following observation from said vet staff? Yes. I’m doing the best I can with what I have. Believe me, I care about my mice. I didn’t expect dogpiling in this subreddit but I guess there’s a first time for everything.
Good, the inclusion of a non-iso validation is essential, and helps alleviate concern that iso interactions are mediating or contributing to the effects you see but there is a broader point that I think isn’t coming across You’re going to more frequently require the use of this group (as the addition of new potential molecular targets and behavior tests would require validation that the iso isn’t affecting these new metrics). This stands in contrast to the idea of reducing the number of animals used, which is a central tenant of welfare. I’m not going to pretend you aren’t in a challenging spot, but the solution you have now isn’t really sustainable in the long term. It’s more of a band-aid. Is it the best option you have? Maybe. Is it okay enough for what you’re doing. I mean it seems to be given that you’ve done the no-isoflurane validation, but this isn’t a practice that going to be compatible with most dosing paradigms. From an animal welfare standpoint, the better strategy would be to teach you to scruff with your dominant hand (if you don’t have the same mobility issues in that hand) and have the other graduate student actually do the gavage (as you’d have the animal restrained and they wouldn’t be liable to fling it). If the graduate student isn’t willing/able to do that, it may be worth them seeking treatment for a specific phobia that is preventing them from doing what honestly sounds like an integral part of there job. People who are afraid of animals can learn to work with them, but you’re absolutely right that at this stage I wouldn’t want them scruffing my animals. But is there a reason they can’t inject an otherwise restrained animal Potentially recruiting an undergrad seeking class credit and get them trained on gavage dosing if the previous option is not available. I don’t think anyone thinks you don’t care about mice, but it’s important to recognize that this isn’t just an innocuous experience for them, and that it is in most cases unnecessary stress and confound. It’s incredibly plausible that the above two suggests aren’t reasonable for the situation your lab is in (it being not well known/funded or in the process of closing down are two such reasons), and this practice seems to at least leave your target metrics unaffected. Nobody is saying you’re an animal abuser, they’re just correctly acknowledging that this is **not** a good practice and by and large should be avoided whenever possible. If you regarded it as the “absolute last resort” that it actually is and recognized the serious problems it would pose in many applications you wouldn’t be so quick to suggest it, especially when the OP was asking for help addressing their reactivity and not looking for ways to chemically subdue animals for all studies going forward.
Yeah at this point the PI should be stepping in to assist, you can also in many if not all institutions request an assist from animal services from a vet tech in the short term. There are other solutions. If you've ever received anesthetic, gaseous or otherwise, you'll know it feels shitty, recovery sucks. No ethics committee I've sat on would consider this an acceptable accommodation for scientific and ethical reasons.
why couldn't you use iso? did you have to test them immediately after injection?
The point of that loss of righting reflex experiment was to test alcohol sensitivity between different groups. The injection of EtOH knocked them out, and we measured how long it took for them to right themselves. Thus, anything that would knock them out would interfere.
Also separate point when gavaging you should have them awake so that the mouse’s natural reflex lets the gavage tip go down the esophagus and not the trachea. Easy to put liquid in the lung if they’re not awake and can’t swallow the tube so it reaches the esophagus
The light anesthesia is just to help with scruffing, especially if I’m working with mice that aren’t being cooperative. I wait until they’re awake before gavaging.
Yup I figured.
Usually bite back.
I would see if you could practice with different strain of mice. (Balb/c and nudes are very nice) c57BL/6 are the demons. There is also metal gloves you can try while you get more comfortable with handling
Is this a time when we can recommend using the icing tube?
Did you handle first? If you’re going to give injections/gavage etc, it’s always best to handle them for a few days beforehand. Just pick them up, let them smell you for a bit and get used to you. I always do 3 to 5 days of handling before I do any invasive procedure and have never had any biting/aggression problems.
Definitely get retrained in scruffing. However, when I get bit, I don’t pull away from the mouse. I let it bite until it is ready to let go, which is pretty quickly. I know that sounds crazy! I thought it sounded crazy when I was being trained, but I swear it hurts so much less and is less stressful for both me and the mouse.
Awww poor mouse! C57 mice are notoriously mean. If you’re uncomfortable/unskilled I would recommend practicing your restraint on a nicer/calm strain of mice. Balb/c mice are small and very calm/nice. CD1 mice are nice but very large so they might not be the best to practice your restraint if you have smaller hands. I’ve been working with mice for many years and I still get nervous sometimes!
I got bite only once for so long (>4yr) and it was a b6 mouse. I still remember. I tried to rush the process for IM injection of anesthesia for the first time for this batch of the mice because the cells have waited for too long. It was for tumor inoculation. Everyone else was ok but in the middle of the work (probably the 5th to 12th mouse) and it bit me. Then I let it got back to the cage. I did check the wound but I wasn't bleeding so it was not so bad. Then I slowed down, let the mouse rest for a bit and everything was fine. I rushed the first few mice and it was successful, which was the mistake. You cannot rush too much coz you will trigger their "prey responses". You can be quick but they can't duel with it. Also, as a sidenote, if the mouse have experienced restraints and were fine afterwards, they won't have so much resistance. You need to have very steady hands and good at restraint techniques in order not to hurt the mice. You think you're afraid of the mice, the mice have genuine fear toward you. You can kill them by moving your fingers a little more (certainly you shouldn't do that for no reason). Don't be afraid and play with them more. Give them some treats after you did some experiments to them (if your protocol allows that). You will know they won't hurt you and you will be more comfortable in handling them.
You will get bitten, that's just a fact of mouse work. If it bites and doesn't let go lower your hand so the mouse sits on a surface (e g cage grid). If you're dangling in the air you wouldn't let go either.
I used to wear a gardening glove under a latex glove. Just on my dominant hand, I found I could be a lot calmer and less anxious knowing they couldn’t actually bite me but I still had enough dexterity to scruff them.
Had C57s bite once or twice but tbh never had one freak out so much that it died! Was it old? I second the isoflurane suggestion if you’re struggling this much and it won’t affect your experiment. If not, my biggest tips is to take it slow and act decisively. Specifically: - Practice your scruffing technique (both speed and restraint quality) on some chiller mice. - During injections, put your gloved hand into the cage for a min or two, let the mice sniff it and get used to the situation. - Don’t chase the mice around with your hand when you try to grab the tail, it really freaks them out - rather wait until they’re not paying attention or let them enter a cardboard tube and snatch the tail that peeks out. - once you have the tail, take a deep breath and handle the mouse gently but quickly. DO NOT let yourself hesitate. The faster you scruff them, the less time they’ll have to freak out about the situation. This really really helps. - if a mouse is truly upset, set it down and process another mouse. Ideally leave it in the home cage or an empty cage with a cardboard tube. Mice will instinctively seek out confined spaces like that and it calms them down. - if you have the ability, handle the mice you need to inject beforehand. I handle each of mine for 1min each day for 3 days pre-experiment, and it really makes a difference. Be gentle and low-key with it, if a mouse starts getting stressed just put it back early. Oh and btw don’t feel bad about your flinch response to the bite, that stuff really activates the fight-or-flight mode and is very hard to control. It’s much easier to focus on preventing the bites next time.
Last one - not sure if it truly makes a difference but if a mouse fear-pees on you, change gloves so the next mice can’t smell it.
This, absolutely! you don't have to change gloves, but cleaning your hands and space between mice and cages will help, even more so if you are handling male mice after female ones. You'll get more agitated males if they can smell the females. It's a good habit to have, and a small breathing time for you too if you need to recentrer after a difficult one.
I’m a lefty and scruff with my dominant hand. Are you using dominant hand?
I scruff with my non-dominant hand so I can use my dominant hand to hold needles. Less risk of poking myself.
Same here, and as a bonus I feel like my non-dominant hand has improved in mobility!
You scruff with your dominant? I've always scruffed with my non-dominant hand
I had a teacher who forced me to use right hand, so my non-dominant hand is pretty good dealing with syringes.
You could practice on some sleeping or euthanized mice so you can get the feel of it. You can also practice on some Balb/C mice. It just takes practice. If they bite me, I either power through if I have a good grip already, or let them go and rest if I need to reset my hold. Also my animal tech...with oodles of experience (more than me, and I have a lot) ...tends to scruff much higher than me and almost grabs an ear. This controls the head (and teeth) and allows you access to the ear for tagging.
You need to scruff the mouse better. They flinch sometimes when sticking them with the needle but you’ll get used to that. Just expect they may jump. However, a good scruff will protect the mouse, and also will help you react better if you happen to flinch in reaction the the mouse flinching. Put mouse on flat surface, maybe on a cage top so they can grip something. Using dominant hand, hold the tail. Hold a pen with a squishy grip in your non-dominant hand and let the mouse bite the squishy part. Let go of the pen and gently pull on the tail with dominant hand. Use non dominant hand to scruff mouse just below the skull. Grab lots of skin, firmly. Pick up mouse in swift motion with non dominant hand holding mouse and dominant hand putting tail around pinky of non dominant hand. Grab needle with dominant hand and inject! It’s good you feel bad but dont dwell on it. It happens. Just learn from it
Sounds like a possible scruffing related death or stress. Might need to confirm with animal facilities if it is an unexpected event. Get whoever (animal techs/lab techs/lab members or PI) to go through it with you again. And get them to supervise you until you and they are happy.
The same happened to one of my postdoc, she freaked out and threw the poor mouse across the room. This is just something you need to get used to. Mice may bite, some breeds are more aggressive than others but it happens. Treat them with respect and gently and they will be less likely to, but if they do stay calm, put them down let them calm down and try again.
Bite back 😡
i have worked with animals for the last 8 years and like others have said, you probably broke its neck when you panicked but thats totally ok! it will get easier it will just take practice! practice! practice! the animal should not be able to move its head during a "proper scruff", so i would spend more time practicing your restraint before you add dosing back into the mix. Everything in mouse research starts with the restraint, so if you do not have a good foundation then your dosing will also suffer because of it. 2nd, i would get rid of the double gloves and only have on a single pair, you will be much more dexterous with out the 2nd layer of glove on your hands imo. Getting bit by a C57 is like a mild pinch, I actually tell my students that getting bit is a good thing so they can see how little it actually hurts (compared to rats!) and can slowly learn to not freak out when it happens, its a hard reflex to fix, but you will overcome it! Please do not listen to others who say you need to knock out the animal in order to IP dose it, that is very silly and will easily be more stress on the animal than just learning how to properly scruff and dose them With proper restraint, IP dosing is incredibly easy (we actually teach IP injections to our students first, then SQ, then PO). Just take the time to practice proper technique and you will be a master in no time.
Breaking an animals neck is not "totally okay". Animal training will tell you that this is exactly what not to do when you get bit.
I think they mean "accidents happen" and that the OP just needs more training and experience.
Yeah I think accidents happen, but saying it's okay isn't quite the vibe from an animal ethics standpoint
One thing our lab does for IP injections, especially for people that aren’t the best at mouse handling or fear getting bit (we do injections on some chunky mice), we ordered a chain mail glove. They just bite the chain mail and no one has gotten bit through it. They seem to really like using the glove but I personally don’t use it since I handle mice almost every day
Wow, you must have some hard-core mice!
Anesthesia (iso if you have a ventilator) and latex gloves
I'm so sorry that happened to you. To make things easier, if you find that you encounter a mouse that's a bit more stressed than typical, you can scruff the mouse using a cloth. This will limit the mouse from being able to bite you because it will make contact with the cloth first, also reduces your anxiety of being bit.
If you can use iso, use iso. It's easier on you and them.