American Fancy Rat & Mouse Association

This article is from the WSSF 2011 AFRMA Rat & Mouse Tales news-magazine.

Colors & Coats

Rat Coats; Wire Haired Rat?; Cornish Rex Rat?; Curly-Coated Rats

By Karen Robbins

Rat Coats

Jack Garcia, Jack’s Mousery, KY, e-mail
rat coat Q Let me preface my email by saying I know very little about rats, but I thought you’re the best person to ask. I was talking to a friend in Colorado who was interested in showing rats, and she showed me some pictures. One of the rats had what seemed to me to be really long guard hairs.

I know that in mice, show animals in standard coat have a very sleek, close-to-the-body coat and that if this were a mouse, the long guard hairs would be a bad thing (not to mention the other faults the rat has).

I know the AFRMA rat standard in the “condition” section references male rats having “somewhat longer and coarser hair.” Is this what it means?

My eyes aren’t trained for rats at all, but thinking about it, I have seen quite a few rats with longer guard hairs like this, hairs that are too long to ever be OK on a mouse.

I’m curious now. How does this all figure in when showing rats?

A Ideally we don’t want the coat to be long in rats, but a lot tend to have longer guard hairs (you can see it on some of the rats on our Standards page The rat in the photo looks like a poor Rex with the coat looking very coarse and sort of curly in spots. If not Rex, then he? looks like he has a very coarse coat and this is not what a Standard coated rat should look like. I can’t tell if the whiskers are curly which Rex rats will have. Males will have a coarser, longer coat than females but not like the one in the photo. Our Standards page shows several examples of male vs. female coats. Long coats are considered a fault in rats. My guess the rat in the photo is a poor Variegated with a white blaze that covers most of his face. His ears don’t look like they have creases or folds in them which is good. Of course, photos of side views give a better idea of the rat overall.

Wire Haired Rat?

Kandice Hobbs, CellarDoor Rattery, IN, e-mail
Q I had a question on rat coats. We keep producing rats with wire coats. Some of them stand up similar to a Rex and others don't but they feel like a wire-haired dog. I wasn't sure what was going on with these guys. Some of the rats were sired by Rex fathers and Rex mothers and some have came from straight haired rats.

A Could be a number of things—either you have Rex rats with a very harsh coat, regular rats with a very harsh coat, one of the other curly haired genes, a combination of genes, or something new. Do you have photos? How many in a litter have this coat? Are they all related from the same family line? When can you tell they will have this coat? Do they retain it throughout life? Is the hair curly at all? Does this coat cover the entire rat or just in a certain area? Do these rats have normal hair coverage or thin and bare in areas? Do they have an undercoat? Are they normal size rats or smaller than normal? How long do they live? Do they have health problems? We need more information please.

Rex x Rex breedings can produce all kinds of different hair coats from short, even, thin coats, to very bare rats with hair just in certain areas, to having patterns. The Rat Behavior web page tells more about the different coat types. I’ve seen both Rex rats with a very harsh curly coat and regular rats with a very harsh straight coat. The regular rats with the harsh coat were just within a family line that produced it.

Cornish Rex Rat?

Alyssa Turney, e-mail
Q I’ve been reading all sorts of articles on the AFRMA website, and it’s great. All the information on genetics and coats had me wondering if you could solve a question I’ve had for some time.

My question refers specifically to Rex genes. Back in March I adopted 4 rats that a family no longer wanted. One of them was male, and so one of the females was very pregnant. I found the male a good home to prevent this happening again. It turns out that another female was pregnant, but she just didn’t show. She managed to keep her single boy hidden from me for about two weeks until I cleaned the cage and found him in one of the nesting boxes. He was such a pretty little boy! His eyes were open, unlike the other litter, which meant to me he was older. The weird thing was that even though the other litter already had a nice coat started, he was barely fuzzy. A week later, he had velvety soft, wavy hair that clung to his body like a Cornish Rex cat. His whiskers were straight. He started growing in stiff guard hairs with his adult coat, and his velvety waves shrunk down to just his head and were eventually obscured by more guard hairs. I have read practically everything I could find on Rex rats and haven’t found a mention of it. Neither of his parents were Rex, either. If anyone could shed some light on this mystery, I’d appreciate it.

A There are several curly haired genes—some dominant, some recessive. Since neither parent was curly haired, then it sounds like your rat could be one of the recessive curly haired genes. This web page tells about the different known curly haired genes in rats There is also the possibility that some of the pet rats have unknown curly haired genes. Do you have a photo of your rat? Are the guard hairs curly or straight? Does he have an undercoat or just the guard hairs? Does his coat change with each molt? Have you tried to breed him back to mom to see if you get more like him?

Sorry we can’t be more specific on what you have. We’d like to hear more about him!

Curly-Coated Rats

Kendra Neitzel, Ratscallions A Merry Mischief, CA, e-mail
Q I have a question or two for you regarding curly coats. One breeder decades ago was breeding “Rex” rats. According to her, they would produce very tightly curled homozygotes, not those awful patchwork rats. She outcrossed to a standard coated Downunder and lost whatever genotype produced the original tight curls. Since then, she gave me what was left of the line and I’ve been trying to figure it out.

Based on Roy Robinson’s rat genetics, there are several different curly genes that are recessive and in different combinations can make nice curls. Can you help me figure out what I’ve got?

A Yes, there are several curly coat genes, but unfortunately not different enough to easily tell apart. Also, since Rex can vary so much in curl and coat, you can have bad Rexes that would match the description of other genes. Have you read the article on the Rat Behavior & Biology page on coat types? Do any of these sound like what you have? Also, read our Rex rat articles,, and (these are also in our Rat Genetics book). You might contact Amy in Colorado (Camarattery) as she has curly rats that when bred together don’t lose their hair.

Don’t know how much I can help. Are yours dominant or recessive? Have you done a test breeding with a Standard? That will help narrow it down to what genes you might be working with whether it is dominant or recessive. Also, we found that certain colors in Rex have a better curl than others, i.e. Agoutis having the better coats where Blacks normally don’t. My mom (who had the best Rexes around for years) had the really good ones all in Agouti. When she outcrossed to make Rex in other colors, she lost the curl.

Teddy Rex
Nichole Royer’s “Teddy Rex” young male rat from a pet shop in 1997.

Nichole Royer found some curly rats in a pet shop years ago. She said the coats were short, very plush, and kinky with wavy whiskers similar to Teddy cavies and was calling them “Teddy Rex.” She describes them as “They really kind of felt like a Teddy Cavy. A thick, almost cottony texture. Their guard coat was coarse enough and stood straight up, but I don’t remember them as feeling particularly coarse or harsh. But they weren’t really ‘soft’ either. It was just kind of like a normal rat coat stood on end and shorter.” When bred together, none lost their hair and she got “Teddy Rex” and Standards. When bred to known Rex, they did not produce any with hair loss either. This cross produced those that looked like Rex with the curly whiskers and coat, and “Teddy Rex” with more of a plush kinky coat and wavy whiskers, and Standards. She didn’t pursue any further test breedings since it was not distinct enough from Rex. Also, Rex can vary on the type of curl their whiskers have from very curled around towards the nose to kinky wavy curled out to the side.

I know there are some breeders who say they have the Cu1 (Velveteen) but the two examples I’ve seen/touched are not even close to the standard/gene for them which calls for a very soft coat—these had a very harsh coat. Also, in talking with one breeder in the past, she said some people got her stock and later were calling them Velveteen when she only ever had Rex, so some of these curly rats out there may just be Rex and not Velveteens like is being labeled.

Keep us posted on the progress of yours. You’ll have to bring some to a show so we can see them.

Q Update: Yes, I’ve read all those articles. They were helpful, but not so much that I was left without questions (I had more questions).

I have done multiple test breedings; here’s what I’ve done:

  • Homozygous curly x Standard = 100% rough coat with wavy whiskers. The babies will have beautiful coats until 6 weeks and after their first molt it looks like they’ve been electrocuted.
  • Heterozygous curly x Standard = some like the ones described above and Standard.

rat coat
One of the really curly female rats.

Here’s where it gets interesting. There are at least two different curly genes here. One produces the scenario above. The second produces a tight, super soft coat with no guard hairs, even on the females. They don’t seem to lose either their coat or curls with age and molting. Unfortunately, I have only been able to breed two of these animals. The male was culled as he was extremely rat aggressive. The female produced two litters and none of the babies have her coat. I’m going to try to breed siblings together (mom is dead) to see if I can get more.

Back to my test breedings. I also took the second curly coat (soft one) and bred it to a Standard and got 50% Standard, 25% like the ones described above, and 25% super soft and curly.

So, what’s next? I have kept an obscene number of these animals and plan on doing all sorts of breeding with them shortly. Kendra

A Sounds like you could possibly have the Cu1 (called Velveteen with very soft curly coat) gene and something else. Or they could just be different versions of the same gene—it’s hard to say. It might be helpful if I could see them in person. You will have to bring some to a show so we can at least see the coats. *

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Updated March 11, 2016