Scrapper is about 5 weeks old. She is a beige hairless and cute as can be.
But everyone here is worried about her. She is very active and into everything,but her belly is huge.
Due to the size of the litter, we started putting boys andgirls into their own cages at 4 weeks, so we dont think she is pregnant,but you bever know.

When you look down on her,her sides stick out and you can see a bit of black on both sides of her.
When yuo pick her up and look at her belly its very dark looking and yuo can see a black band going around her.

What could be wrong with her?

I would have her checked out at the vet for megacolon, as that's what it sounds like to me.  Can you keep her on her own for a day or so to see if she's pooing/the type/consistency?  With megacolon, the nerves that control the intestine don't work properly, and so they can't pass anything, and there are a number of nasty ways it eventually will kill them.

There are -some- treatments for MC, but as young as she is I'd be worried it was early onset, in which case euthanasia is really the only option.    I really hope that's not the case.


MC babies from the mom I took in earlier this year:
http://i229.photobucket.com/albums/ee299/ohmaibobby/168.jpg
http://i229.photobucket.com/albums/ee299/ohmaibobby/166.jpg

They have fur, but you can see the body shape.  They were about 4 weeks old there.  They were very active, but as MC progresses lethargy and other symptoms can emerge.

http://ratguide.com/health/digestive/megacolon.php

I would get her to the vet ASAP just to get a proper diagnosis, but it doesn't sound good.  :/  I wish I could be more reassuring. 

In Quinn's litter, there were 4 babies, and all but 1 had it.  The one that did not have it is still alive and thriving (She's still with me.) but the babies that did have it were either high-white (had a blaze) or were splotchy.  I have no idea how it would be noticeable in hairless rats, but if it's shown up in her I would imagine the others would either be showing signs, or noticeably had it by now.  It's a genetic problem, so the risk is there.  It may be a good idea that if it is confirmed in her, that you contact the adopters just to let them know what to look out for, and have the other babies checked out.  If it's later-onset MC, and it's not a severe case, there are things you can do and the rats can lead relatively normal lives, they just need special diets and enemas.

Size differences can indicate problems, too.  If the other girls are looking normal, I would think they are probably fine, but I would have that one boy who was smaller then the others checked on just to be safe.

I think headspots are high-white, but I'm not 100%.  Nina (the girl who survived Quinn's litter MC free) has a little white triangle on her chest, so I wouldn't worry about spots on the belly.  Blazes/splitcaps/white that goes up the side (I think that's cap stripe, but I'm a real idiot on markings. ) are all high-white I believe.

http://www.dreameyce.com/eagleseye/rattery/ratinfo/rat_markings.htm

There are several genes that can cause head spotting. The high white gene can cause it and is the one associated with megacolon. If this was a planned breeding, you don't want to breed these parents again or any rat related to these parents. If it was accidental, I'd recommend getting them neutered so you don't have any other accidental breedings. If they came to you as rescues, thank you for taking them in and giving them homes. It's heartbreaking when megacolon turns up in a litter. The only way to get rid of it is to make sure the parents never pass on that gene.

I'll keep my fingers crossed for your little one and her litter mates.