# Weak immune system



## Lyra (Mar 1, 2013)

I've recently acquired few mice of much better type than the ones I have now. Using them could let me skip years of selective breeding for type! 
The problem is, their immune systems are really weak compared to all of my other mice...

My poor, pet-typed mice sneeze sometimes, but very rarely - it happens once in few months (usually after airing my flat), although some of them have never been ill in their lifetimes (oldest of them is now 1 year old). Few drops of multivitamin in the water bottle and eucalyptus oil in their bedding ALWAYS works. The only mouse that ever needed antibiotic was 17 months old. I have never bred mice prone to diseases, and I always picked the healthiest ones from the litters.

Now, I have no idea what to do... The typey mice I've got are all 4-6 months old and they always seem on edge of disease. But there is nothing wrong with the place they are in! The temperature is ~23 Celsius degrees / 73.4 F at daytime, around 2 degrees less at night. All of my other mice are fine, even those they have constant contact with! Sometimes, they have their eyes glued shut or their fur is strangely fluffy. 
Few times my home methods helped, but now they seemingly at random got skinny, sneezing and hard breathing - and the only solution was to give them antibiotics! The 6 months old male is treated 2nd time already, the 4th months old male his 1st. But they are both so young! The females didn't got that ill yet, but they do sneeze a lot.. And of course I'm not able to get more typey mice... :evil:

Is there any chance I could improve their immune systems somehow? Like breeding males with healthy females, or fostering sneezy does' pups with my females? Or should I just exclude them from breeding at all in your opinion?


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## SarahC (Oct 3, 2008)

I have been in this position more than once.Weak mice,nowhere to get healthy ones in the chosen colour from.It would depend on the variety whether I crossed to a different line of mice but generally I wouldn't.I would breed from all of the available individuals and from every litter keep only the healthiest.Colour and type may suffer temporarily.You need a lot of patience,it takes about 2 years in my experience to fix health and then put the colour and type back if you only have a small group of animals.It can be very disheartening at times .


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## Lyra (Mar 1, 2013)

Thank you for quick response, *SarahC*! You've made me feel hopeful again!  2 years is a long time, but certainly it's much better than resigning...

I have to admit I've started feeling depressed by watching them all getting sick out of the blue... It crossed my mind that maybe I've made a mistake by buying them - breeding mice is my hobby, but I feel really tired as I'm trying hard to keep those new ones in moderately good condition.

How do you go in choosing mice from the litters in a project like this? Even my first mice weren't as weak as those new ones are, so I'm not sure how careful I should be now... I've always left around 2 times more mice than I've wanted to keep and chose the keepers when they were around 10-12 weeks old. Would it be enough to watch out for sings of poor health now?


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