# question about hairless



## Erica08 (May 20, 2009)

Can someone fill be in on hairless and how it's inherited? I thought fuzzy mice carried one copy of the hairless gene then a completely hairless mouse had two copies of the hairless gene? And how long does it take for a hairless/fuzzy (they both start out furred correct?) to start loosing hair?

I'm fairly sure I don't have the genes in my mice as all my adults/breeders are fully furred but I've noticed several kits that have very thin fur especially on their nose and face. But right now I have one who I put in an Iso. box because he has been loosing hair like mad but the skin looks good it's not crusty or scabby like I'd expect if she had mites, or any parasite for that matter and no one else in the cage is loosing fur or sick so I'm not sure what's going on. I'll try and post pictures of her but I can't get my camera to focus on her (the poor things so ugly she's breaking the camera lol)
The mouse appears healthy other than a little thinner than I'd like.


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## WoodWitch (Oct 18, 2009)

Erica08 said:


> Can someone fill be in on hairless and how it's inherited? I thought fuzzy mice carried one copy of the hairless gene then a completely hairless mouse had two copies of the hairless gene?


No, both fuzzy and hairless are recessive genes, so _two_ copies are needed


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## Rhasputin (Feb 21, 2010)

Fuzzy and Fuzzy hairless are seperate genes from Hairless.


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## Jack Garcia (Oct 9, 2009)

Tratallen and Erica, you're both (partially) right. Hairless is complicated because there are a few different ways to create a hairless mouse, and all are slightly different. To make it even more confusing, what we call "hairless" is often not really hairless (hr/hr). These are the ways to get hairless mice:

1) Hairless. This is hr/hr and is recessive. It causes loss of hair, whiskers, and all pigment. It is rare. Jenny (WNTMousery) has it, but I don't personally know anybody else in the US who breeds it. This kind of hairless is sometimes called "true hairless" to distinguish it from fuzzy hairless. Females have trouble nursing (nipples are modified hair/sweat glands, and theirs are messed up), so you have to breed male hairless X female carrier repeatedly.

2) Fuzzy-hairless. This is a fuzzy mouse (fz/fz) who has been bred to be as hairless as possible. They often have Caracul or Rex as well. They lactate normally.

3) Nude. Then there's the nude (nu/nu) mice, which resemble true hairless and are denoted nu/nu but in 10+ years of mousekeeping I've only known one person who had these, and they were directly from a lab. They have severely weakened immune systems so are hard to keep alive outside of a lab.

4) Dominant hairless. There's also a dominant variety of hairless in Europe, but I've only heard anecdotal stories and seen pictures from France. As far as I know it's unknown in labs.

5) Another one. I suspect there's another kind of hairless recessive in Europe as well, as I've seen mice who look identical to our true hairless but have pigment, and it's inherited as a recessive. The person I spoke to said they lactate normally, as well.

When you thought that one copy made fuzzy and two made hairless, you were probably thinking of rats. I don't know a lot about rat coat mutations, but I know they have one which operates similarly.


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## Rhasputin (Feb 21, 2010)

One copy of rex in rats makes rex, and two copies of rex in rats makes a double rex, which can sometimes appear hairless.  
Or have hairless patches.


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## Jack Garcia (Oct 9, 2009)

There you go!


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## Rhasputin (Feb 21, 2010)

They rarely look completely hairless unfortunately. . . usually they look like they had a fight with a hair dresser. :?


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## WoodWitch (Oct 18, 2009)

Jack Garcia said:


> Tratallen and Erica, you're both (partially) right. Hairless is complicated because there are a few different ways to create a hairless mouse, and all are slightly different. To make it even more confusing, what we call "hairless" is often not really hairless (hr/hr). These are the ways to get hairless mice:


Yep, I was being a bit literal about the fuzzy (fz/fz) and hairless (hr/hr) and not taking into account all the other ways


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## Erica08 (May 20, 2009)

Hum? Then I'm not sure what the heck I have :lol: .
None of my adults look to be rex or caracul so it shouldn't be a fuzzy-hairless. That leads me to think it's environmental rather than genetic maybe an allergy issue? When I moved her to the iso box I put her on shredded paper rather than the aspen so I'll see if that changes something.I'm sure it's not mites as I asked on here and she nor any of my mice have signs of mites(though I'll treat just in case).
I'll get a pic of her tonight or tomorrow morning and post it that might get some better answers.


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## Erica08 (May 20, 2009)

Rhasputin said:


> They rarely look completely hairless unfortunately. . . usually they look like they had a fight with a hair dresser. :?


That's how she looks but I just don't think the genetics are there.


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## Jack Garcia (Oct 9, 2009)

It can't be shown, but I think it looks kinda funny, like I do when I first wake up.


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## Rhasputin (Feb 21, 2010)

Here's a picture of a Fuzzy hairless mouse


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## Erica08 (May 20, 2009)

See that's in the category of so ugly your cute. Mine looks similar she has bald spots on her legs and belly and very thin on her nose.

What where the parents and genetics for that one.


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## Rhasputin (Feb 21, 2010)

Parents were both fuzzies with rex in them.

Some fuzzy hairless can have bald patches. If your mouse looks like that one, with some bald patches, that's probably what she is.


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## Erica08 (May 20, 2009)

Here are the pics.

Balding face








Hairless tummy some guard hairs but that's about it








balding patches on side and upper leg


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## Rhasputin (Feb 21, 2010)

Hmmmm. . . That actually looks like either a hairless, or a health issue.


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## Jack Garcia (Oct 9, 2009)

It looks like sarcoptic mange to me.


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## Stina (Sep 24, 2010)

I saw coats like that a couple times at the pet store I worked at in litters....no idea what caused it, but many of the pups that had that hair loss didn't grow as quickly and weren't as thrifty as others that didn't...those that survived (and weren't sold as feeders....) ended up regrowing all the hair.

Jack, what makes you think sarcoptic and not a demodex type mange?....by the way I know NOTHING about mange in mice...so I don't even know if they can have demodectic mange...lol I just know in dogs demodex is common in immunocompromised (young/old/inferm) animals, tends to affect areas like the face and belly, and can be treated fairly easily...and can resolve itself in less severe cases as immunity improves. Only very young animals have the fur loss would seem to suggest a demodex mite over a sarcoptic mite. (again, I know nothing of mange in mice...)


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## Erica08 (May 20, 2009)

I wondered about mange too but the skin looks healthy and in animals I've seen with mange or any time of external parasite the skin looks bad either scabby, or dry, or flake like dandruff. He's just over 3 weeks so he is a little small but then he's out of my smallest doe so that makes it hard to tell.
He's the only one that currently looks like this so if it's a health issue I think it's something like allergies may to the bedding. I'll keep him around as long as he looks healthy and see if things change now that he's by himself and on paper rather than aspen.


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## Stina (Sep 24, 2010)

I have had mice allergic to aspen myself and they've had hair loss...so hopefully that's all it is!


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## Jack Garcia (Oct 9, 2009)

Oh, it could be demodex mange (or other things), I'm sure. I also have no experience with mange in mice, although I've seen it happen in rats before.


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## WillowDragon (Jan 7, 2009)

There is a type of hairless mouse that starts off with hair and then loses it as they wean...










Ugliest darn thing I have ever seen if you ask me! :shock:


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## Jack Garcia (Oct 9, 2009)

That's the type Jenny has. They eventually look like they have hula skirts on.


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## Erica08 (May 20, 2009)

Yeah I commend those that work with hairless I can't do it I think their ugly as sin


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## Erica08 (May 20, 2009)

We'll theirs more of the little rug rats in a litter I just weaned they all start out the same way with thinning hair on their bellies so I'm fairly sure it's genetic. I've got one male who only has thinning crimped hair and two more does with hair loss on their backs and sides.


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## Stina (Sep 24, 2010)

Has the hair loss all started at the same age, or no? If its started at different ages, I doubt it is genetic.


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## Erica08 (May 20, 2009)

It's all starting at about four weeks. I did notice in this litter at about 10 when their hair is coming in that it was thinner on the stomach then at four weeks it progresses to the sides and back.


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## Erica08 (May 20, 2009)

So I was able to sort through all my grower tanks and find everyone with unusually hair growth and this is what I found
3 bucks with varying degrees of hair loss
1 doe with hair loss
1 buck with thin wavy hair on his stomach
Then I have one doe that looks like she might be caracul she resembles the photo of the adult caracul on the fun mouse page.
All the kits have the same father most of the babies come from a poor black doe who I noticed had wavy stomach hair but if you look at her from the top you can't see any difference. The "caracul" kit and the original hairless are from two different mom's.
Here are some pictures of the other hairless
























Here is the possible caracul doe
















Here is a standard coat for comparison


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## shadowmouse (Sep 17, 2010)

The first white one you showed with the hair loss... Did that one come from the same mom as my RY Dutch? Because she has considerably thinner hair then the others I got from you.


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## Erica08 (May 20, 2009)

she might have I can't remember for sure but the satin colored rump she had the wavy belly hair. I used the same buck for most of my litters (broken champagne tan) it's just recently that I started using my other two boys.


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