American Fancy Rat & Mouse Association

This article is from the WSSF 2015 AFRMA Rat & Mouse Tales news-magazine.

Colors & Coats

Peach Fuzz Hairless Rats; Baby Mouse With Fur Loss; Producing Hairless Rats; Size of Hairless Rats

By Karen Robbins

Peach Fuzz Hairless Rats

Holly M. Sherrah, Canada, e-mail
Q I have two ratties which I’ve been calling Peach Fuzz Hairless and would like to know what variety they would actually be considered. Both rats have an extremely short, sparse smattering of wavy hairs over their bodies, tightly curled whiskers, and fuzzies on their little faces. Kricket is a particularly interesting example. When he was a baby (about 3 weeks old), his coat looked much like a Rex’s. Then by the time he was about 4½ weeks old, it became extremely short, soft and velvety. His fur remained like this for a few weeks, then he started to become naked. By the time he was 3 months old, he was pretty well hairless as described above.

I know that these boys are not true Hairless rats. I also do not believe them to be Double Rex, as once their fur fell out, it never came back; plus they both have fuzzies in the exact same location on their faces. What would you call this variety?

A Looking through the photos they look like a Hairless with fuzzy face, a Hairless with too much fuzz on the body and face, or a homozygous Rex.

For show purposes, the ones at 4 months old would be entered in the Hairless class but be faulted for having a fuzzy face (they also usually have fuzzy feet). There are several Hairless genes so it’s hard to tell what all is out there in the fancy population. In the early days before true Hairless had been obtained (completely Hairless ones), breeders found they could make Hairless by constantly breeding Rex to Rex; however, these always had some body fuzz/fuzz on the face.

Since you say your rats never got hair back after they lost it, like Homozygous Rex go through at times, then it sounds like they are one of the Hairless gene rats with fuzz on the face.

The Rat Behavior and Biology web site has information on the different Hairless genes.

Update: That was quite helpful. I am curious, do true Hairless rats also lack those short, bristly hairs on their tails? I have a pretty bad contact allergy to my ratties, and I’ve found that anywhere they wrap their tails around me is where I will get the worst hives! I’d be interested in handling a rat with a hairless tail to see if I have the same reaction.

I am a little concerned about the mention of kidney failure in fuzzy rats. Jethro has had blood in his urine for the last 3 months. We’ve done a basic urinalysis, blood panel, ultra-sound, and x-rays; have treated for both infection and parasites, but all results have been normal and nothing has helped. He’s about 21 months old, and has no other symptoms. Is there any way to prevent/treat kidney disease in rats?

A About the completely Hairless rats not having hairs on their tails, that I do not know. It has been years since anyone has shown a completely Hairless rat and I don’t recall if they did or didn’t.

Regarding your allergy, you might try washing their tails before handling to see if that would help or make sure you wear long sleeves. We have an article on animal allergies that may have some helpful info.

Hairless rats do have a lot of problems but I haven’t heard from fanciers of them having bloody urine as a common problem associated with them—this has been more common in Tailless rats. We have an article on Kidney Stones vs. Kidney/Bladder Infections regarding Tailless rats that may help answer some of your questions.

Since it is unknown what Hairless genes are actually in the fancy population, it’s hard to say if Jethro has kidney problems due to being Hairless or something else. The article you mention says they don’t normally live as long as your guy so I would say he is doing pretty good considering, though it would be good to know what is causing his problem.

Baby Mouse With Fur Loss

Nancy, e-mail
Q I raise mice to feed a ball python. I keep the breeders till they die since I become fond of them. I have been raising them carefully for around 12 years, avoiding inbreeding. I have one 3-week-old mouse with no fur from his neck down, white fur from the neck up on his face Baby mouse with fir loss Baby mouse with fir loss which looks normal. He appears to have whiskers. The skin looks good and he seems healthy and happy otherwise, but a bit small. Rest of that litter was black and white. There were 6 others in the litter and they all seem in fine shape—they have all their fur.

All my mice are kept very clean and well fed, with fresh veggies, milk, oats, seeds, etc. I have never had any kind of mange or coat problems in all the years I have kept mice. None of the others have any problems. Is this unusual? This is the first time I’ve had one like that turn up.

I’ve sent along a few shots of the bald mouse. Sorry for the blurry photos, but he just wouldn’t pose. He seems quite cheerful. I don’t think he has any particular discomfort or anything. Do you think he needs any lotion or anything? He never did grow any fur on the most of his body. I noticed him when the rest of the litter started to get fuzzy. Actually, it seems like he did have a little more, closer to his ears, so not sure if he will lose it all. Anyway, he is very sweet and cheerful, so I will just keep him as a pet and always make sure he has friends to curl up with at night (maybe breed him). Thanks for looking.

A It looks like some kind of hair loss mutation of which there are several. The Hairless we have dealt with will start losing their hair on the nose and work its way back until they have no hair at all. Your mouse looks more like what some adult Hairless rats look like with the fuzzy face and feet. He looks healthy otherwise. Let us know if he keeps this bit of fur into adulthood or if it all molts off in a few weeks.

Producing Hairless Rats; Size of Hairless Rats

Jozzette Hagemann, Jozzy’s Rat Pack Rattery, CA, e-mail
Q If two rats mate that are each half Hairless, can they produce any Hairless babies in their litter? What is the average weight of a 9-week-old rat? I just got a Hairless doe from another breeder and it weighs 182 grams and it seems small, but maybe I am wrong.

A Yes, you should get Hairless kids. The different Hairless genes are all recessive so breeding two furry rats that carry Hairless will produce some Hairless kids. The AFRMA Rat Genetics book (Other Interesting Coat/Color/Misc. Genes section in the back) goes into more detail about each Hairless gene.

The guidelines we have for furry rats are: 6 weeks – males to be 8 oz/approximately (~) 236 g, females 6 oz/~177 g, 4 month females 11 oz/~311 g.

Hairless usually run a little smaller. Also, since they have no hair, they will look smaller even if they weigh the same as furry rats. Since I know you have had Hairless kids in the past, use your judgement based on your experience as to whether it is average or small. *

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January 1, 2019