New born mice dying

Question
Dear Natasha!
We had two female mice give birth to 13 baby mice 11 days ago. They seemed OK, with both mothers taking care of all siblings - they are now furry, eyes not yet open, still breast feeding, sometimes crawling around. We did not touch anything for a week after which we cleaned their living space, removing the two mothers first, and then the mice - not touching them - onto a paper plate - and then put them back again. Everything was back into normal. Last night we cleaned the cage again - same way, only this time we put the baby mice in a small cardboard box while the cleaning took place. Neither cleaning lasted longer than 10 minutes. Room temperature is stable and well within the suggested range. Today the baby mice started dying one by one - already 4 are dead and we are very worried. After the baby mice die, the mothers eat them, it is horrible to watch.
This is our first time having baby mice and would like to help somehow. Do you have any ideas? Can we still save the other 9 somehow?
Thank you,
Petra

Answer
Dear Petra,

I'm so sorry to hear of this situation.  How terrible for you and the mice.  You did nothing wrong.  Even if the mice had gotten a little cold during 10 minute cage cleaning, at this age that should have no effect on them.  I'm glad you understand that the mothers (think they) have to eat the dead babies, and they are not killing them.  

Since both litters are dying, we can pretty much rule out genetics-- unless the father is the same mouse (if he is, I would not mate him again). If it were genetics there would be nothing you could do anyway. Something is killing the mice, a bacterial infection, virus, chemical, or parasite.  They are too small to be treated for anything, even if you knew what it was.  

Examine the mother mice carefully for any signs of illness or stress. Are they behaving any differently?  Is their fur clean and smooth, backs straight, no sneezing or discharge?  Also think about about their environment:  Have you used any room deodorizers, furniture polish, or harsh cleaners in the area?

I can't give veterinary advice, of course, not being a vet.  If you have a mouse vet-- specialist in exotics or pocket pets-- you could see if they would see the litters and mothers together. If you are able to do that, bring in the whole cage.  The vet will likely want to see the living environment.  If you can't find a specialist I wouldn't bother with someone else.  I have put in a call to the other mouse expert, Cass, who has some vet training, and if she has any advice she will call me back-- I suspect she won't be able to say any more than I can.  Anyway a phone call is faster than an email through here.  I also put in a call to my mouse breeder, who isn't a vet either but might have run into this.  The question in  my mind is whether to try treating the mothers with antibiotics, or if that might kill the babies.

I am sending this off to you now, but if I hear back from anyone I will add that information and immediately send a revised answer.  

Again, I'm so sorry.  Best of luck.

squeaks,

Natasha