# Piebald mega colon



## Kosmo (Apr 18, 2013)

I'm having a frustrating time with my broken marked mice. I understand that mega colon can be a problem with piebalds, with a frequency of 10% attrition often cited, but I seem to be getting somewhere closer to 20-40%. At first I wrote it off as bad luck, and it may still be, but I will admit that I'm beginning to wonder if there are different piebald genes out there that produce different frequencies of this deadly problem.

I'm crossing my piebalds with a wide variety of different mice, from a wide variety of sources, so I've done all I can to change up the genetic background on which the gene is expressed, but just today I see that my best marked mouse will probably be removed from the gene pool due to this problem. It is very frustrating to keep losing my best young mice to this, and I'm considering changing up to a different piebald gene, if it will do any good.

Right now I also have some nice belted mice that have never shown a single instance of mega colon. Does anyone have any insight into this issue?

Am I increasing the likelihood of the disorder by outbreeding so much? (thus bringing genetic backgrounds into the mix which haven't been vetted, so to speak, by previous viable generations of piebald expression) If I breed only the piebalds that don't have the problem, is it possible to lower the frequency of mega colon?


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## SarahY (Nov 6, 2008)

Hello Kosmo, I'm sorry you're experiencing this problem. It is heartbreaking to see litter after litter of young mice with trouble.

If you are keen to keep the piebald line, which I assume you are, then you must inbreed to weed out this problem. By breeding only the mice that make it to breeding age in good health, you should reduce the instance the mega colon in each generation until eventually you've got rid of it altogether. Unfortunately, Nature has a way of mocking maths and genetics, like those times when you pair two mice and have a chance of 25% of the litter being a certain recessive colour, and the whole litter comes out that recessive colour. Similarly, you may end up with no healthy piebald mice at all. The odds of this are low, but the only thing you can do is keep breeding the healthy piebalds together.

I hope this helps and I wish you the best of luck with this.


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## tsunamis (May 25, 2012)

It's entirely dependent on what type of piebald gene (or combination) that you have. seems like W* is mixed into your line? Anyhow it's possible you may need to scratch some if not most of your current stock. Sorry to say that, but it's simply not worth loosing your mice like that.

I also breed piebald and have never had a case of megacolon in them. I do consider myself very lucky.


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