# How to deal with genetic flaws?



## icedmice (Oct 4, 2009)

I lost a mouse tonight which I suspect died from a possible genetic flaw in the line.

There is suspicion at the moment a paticular breeder has supplied mice with questionable health. To my knowledge nobody has had them necropsied by a vet to be absolutely sure of the cause of unexplained deaths, a good proportion are now descesed before reaching 1 year of age. One of the founders (the doe) of my line originated from this breeder.

The unfortunate thing is I have already reached the F2 generation in the line before I experienced an unexplained loss of a mouse myself. I was hoping against hope I wasn't going to experience the same dramas others have, it appears something nasty is possibly lurking in my line too  . 
I know it's only one death but enough to alarm me because normal healthy mice typically don't drop dead at 4 months of age!

The original founders of the line are still alive and well both are 10 months of age.

the F2 generation was crossed to a line with better form and history of health. I'm glad I did that in the end.

I'm thinking about crossing back to the buck who founded the line to maintain the integrity of the mice being produced. To my knowledge no mice from his side have had health issues apart from obesity which seems to be really common amongst Aussie mice :roll: . 
Interestingly these fat mice live to an average of 1.5-2.5 years of age, that's a seperate issue I'll need to address.

The mice in this dodgy line are remarkably easy to handle and have some really good qualities I can't afford to loose so early in my programs. 
Not necessarily qualities you'd look for in a "show mouse" at this stage but ideal for a fuzzy friendly-faced companion animal.

It's not so easy just to let go of a line at my mousery I only have about 40 mice and most are retired. I'd be lucky to have 10 mice who are eligable to be breeders, most are bucks :shock: . 
I have had 3 litters recently because the situation with the choice I had was becoming rather desperate! - I'm in danger of loosing a couple lines if I leave things too long.

My plan to combat the issue is to breed from does as late in their breeding life as possible, and regularly outcross to lines with better health (and form- because it's rather average at this stage).
Outcrossing will occour every second generation until I no longer experience issues. I'm keeping a few bucks from the line to monitor longevity, bucks one year and older will be used to line breed.

Otherwise is there anything else I should keep in mind?


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## moustress (Sep 25, 2009)

How did the mousie die? Like, symptoms and time after symptoms until death?


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## icedmice (Oct 4, 2009)

She became lethargic the day before but I wasn't sure if that was because she was sick of if I'd just woken her. It was 2am when I last saw her alive.
Apart from that there were no physical symptoms that indicated poor health.

That's why it puzzled me.

Perhapse I'm overreacting. It's the first and only unexplained death in that line that I am aware of. I have most of her family here with me and nothing seems to be the problem with them.


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