Hello,
I'm currently under the experiment with C57BL6 mice, male, 8 wks
Q1. They fight a lot, what can I do for this?
There are 6 mice in each cage initially, and I have been separating the most aggressive one from the cages, but it seems I need other solutions..
Q2. Is a fight without bleeding or severe injury admissible? is this just normal thing?
Q3. What do you think if I use female mice rather than male mice for liver metastasis model? (Cell line: MC38)
Thank you,
Cheers,
I'm afraid I don't know anything about the model you are using, but I have some suggestions for fighting (I used to be an animal technician).
When cleaning out the cage, some of the dirty bedding or sawdust can be transferred to the new cage. Mice often have to fight it out when they are put into the new clean cage, as they are missing all the smells telling them who's in charge. I don't know how strong the evidence is, but a technician colleague presented a poster saying this helped with fighting, and ever since then I always do it. It sounds gross, but mice like the smell of their own urine. Also make sure the cage has some enrichment, like a small tube. The weaker males can run in there to escape the dominant mouse. Finally, ensure they are not exposed to a stressful environment. The smell of unfamiliar male mice will upset them. Lots of sound in the room where they are housed is also stressful, and bear in mind mice can hear in much higher frequencies than we can. I have known building works to causing fighting and pup-eating before.
That said, some fighting is to be expected. Mice maintain a hierarchy in their cage, and enforce it with fighting and grooming. You will especially notice this after cleaning out, as I said before. If there are no injuries at all, I think it might be worse to split them up, as they are social creatures, and are stressed on their own. However, if they have lots of scabs and injuries, they can't be left to be bullied. I can only say what is admissible by the UK Home Office though!
I'm afraid I don't know anything about the model you are using, but I have some suggestions for fighting (I used to be an animal technician).
When cleaning out the cage, some of the dirty bedding or sawdust can be transferred to the new cage. Mice often have to fight it out when they are put into the new clean cage, as they are missing all the smells telling them who's in charge. I don't know how strong the evidence is, but a technician colleague presented a poster saying this helped with fighting, and ever since then I always do it. It sounds gross, but mice like the smell of their own urine. Also make sure the cage has some enrichment, like a small tube. The weaker males can run in there to escape the dominant mouse. Finally, ensure they are not exposed to a stressful environment. The smell of unfamiliar male mice will upset them. Lots of sound in the room where they are housed is also stressful, and bear in mind mice can hear in much higher frequencies than we can. I have known building works to causing fighting and pup-eating before.
That said, some fighting is to be expected. Mice maintain a hierarchy in their cage, and enforce it with fighting and grooming. You will especially notice this after cleaning out, as I said before. If there are no injuries at all, I think it might be worse to split them up, as they are social creatures, and are stressed on their own. However, if they have lots of scabs and injuries, they can't be left to be bullied. I can only say what is admissible by the UK Home Office though!
I agree with the suggestions from the lady above. C57s are notorious for fighting, unfortunately. There have been times where data can differ between males and females, so I would be careful when thinking of switching sex in an experiment. Maybe run a small pilot study and see if there are any sex differences for your particular model. Is there any reason you could not singly house these mice?
You can only keep male C57BL6 mcie together which are littermates and which never lived for a longer period separated. Never put males together after they were allowed to mate with a female. If you are not too much limitted with the strains and substrains, you might want to use a mouse strain that is less agressive (like C3H or BALB). Also, C57BL6 exists in different substrains (such as /J or /N), which differ dramatically in their behaviour. Maybe you try one of those or check the Mouse Genome Informatics / JAX-site for information of the substrains behaviour.
regards, Michael
We routinely use C57B6 mice and fighting is to be expected. As the others have posted, however, there are things you can do to reduce it: enrichment (like huts or tubes), bedding transfer (a little bit), etc. Great suggestions above. Also, if the males aren't weaned together, we do not place them together. If you are placing them in cages together at 8 weeks, they are going to have problems. We write into our protocols that male mice may be singly-housed if no littermates are available. Good luck and thanks for caring so much about your animals!
Aside from the suggestions from others that I agree wholeheartedly on, you could try to reduce the number of mice per cage. We place maximum of 5 mice per cage. Naturally, they should be littermates. If they are too crowded, the fighting is worse.
I agree with all the suggested solutions above. Just would like to encourage you to go on with your studies. We are working a lot with this mouse line (from JAX). In general, I only keep 3 mice of that age in one cage, and yes they have to be litter mates and kept together all the time. The transfer of a little bit of the bedding did help with our mice a lot, and yes changing gloves is annoying but helps a lot. Noise is another good point, avoid loud music and pushing things around when you work with these mice. Another thing to add and that is true for any mouse strain I have worked with, the mice are only as calm as you are. Be confident in what you are doing, don't stress anything and be calm. Regarding the male -female issues, there are huge differences in sexes, be very careful in switching. I would not recommend doing it in between your experiment. Good luck!
I have been using C57 mice for a while in tumor models also, I agree with everything. On my experience they are always seeking for troubles. If you buy the mice, ask for animals as younger as possible so they can be easy adapted to lab and cage mates before experiments. What is more important is to reduce animals per cage to half of the recomended number and never mix animals from different batches or after been separated even if they came from the same batch.
Q3 - I strongly advise against switching your model from male to female mice, especially if you already have data in male mice.
- In terms of the relevancy of your model to liver cancer, men have a higher risk of liver cancer than women (http://www.cancer.org/cancer/livercancer/detailedguide/liver-cancer-risk-factors)
- The gender disparity in liver cancer may be due to lifestyle & environmental factors, but many studies suggest that the androgen receptor plays a role in liver cancer (http://dx.doi.org/10.1530/ERC-13-0283)
The Mouse Cubby https://mousecubby.com/ has been shown to reduce aggression 50 to 90% in mice.
- Badges
- Science topic
- Similar topics
- Medicine
- Disease
- Disease Models
- Animal Models
- Rodent Models
- Mouse Models