# Problems with homozygous rex?



## madmouse (May 19, 2012)

In a particular line of my mice I have had 4 mice born from three different litters that had abnormal coats. The coats on these mice look like perfectly normal rex/texel coats at first but then within a few days to a week after they get their coats, the fur deteriorates overnight, becoming very sparse and brittle (much like a fuzzy coat). In three out of four of them there was pretty extensive hair loss affecting anywhere from 30-90% of the body. Two of the affected mice were does. They had less hair loss, normal body size, and eventually their coats reverted back to the rex/texel texture. The other two affected mice were bucks. The bucks stopped growing normally around two weeks and grew up to be about half size. One looked like a texel, went 95% bald, then regrew a coat that looks like a fuzzy hairless. The other buck had a texel coat, which turned into a fuzzy type coat, then he turned into a true hairless (none of the other three are TH or TH carriers), but his coat fell out all at once instead of the usual pattern. A fellow texel breeder told me that what I was seeing were mice homozygous for rex. Would Re/Re cause the bucks to be so small? The bucks did not start out small, but stopped growing when their costs went wonky. Otherwise all four mice are healthy and fertile. Coincidentally (or not?), all four of these mice are merle, which was an accident. The parents were all carriers. Anybody know what I'm seeing in these mice? Could it just be double rex?


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## PPVallhunds (Jul 26, 2010)

I'd be wondering about a fungal problem with them, I had a litter where I thought they may be long hair as there coats looked diffrent a tiny bit wavy, then the fur started falling out so thought they were some sort of hairless. Was told fungal as the fur didn't start at the face so treated with athletes foot powder and eventually the fur grew back. I didn't think it was as the skin looked perfectly healthy but as it got better it mist ha e been.


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## madmouse (May 19, 2012)

I hadn't thought of that possibility. I had a ringworm out break amongst some new stock back in December. Though the symptoms of those mice were not similar there's certainly a possibility that some sort of fungal spores have remained in the mousery. Next time I see one of these weird coats I will give the foot powder a try. It certainly couldn't hurt.


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## PPVallhunds (Jul 26, 2010)

Here's pics of mine when they fisrt started losing fur, they ended up all most bald then all grew back. The older litter and adults in with them were completely fine.
viewtopic.php?f=27&t=10867


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## Rambo-Bright (Jun 5, 2013)

I've produced homozygous rex mice (double rex) in a few litters and it is normal for them to moult nude before regaining their coat. They don't stay nude for long. I've not noticed any issues with growth at all in double rexes, mice have been just as large as their litter mates and grown up to be good sized adults (good sized for mice in Australia). I have a female at present who is a long haired double rex, and she tends to get bald patches at the back of her neck on occasion, as a youngster she moulted nude before regrowing her coat.

Even in rats double rexes are known to go sparse, and moult nude before regrowing their coat. They do this at about 6 weeks of age. One of the ways to tell the difference between a heterozygous rex and a homozygous rex in a litter when young is that the homozygotes will moult nude or almost nude (texels tend to retain the longer guard hairs) around 5-6 weeks of age.


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