Rabbit Coat Color 101

[Bunnylady]

"If I breed this rabbit to this rabbit, what colors can I get?"

If I had a nickel for every time I have heard some version of that question, I might not be on easy street, but I'd sure find it easier to pay my feed bill.

And with all the times I have seen someone's eyes roll back in their heads as I try to explain why they'll get those colors, I think I may have found a new technique for hypnotists.

It's not that bad, guys - really.

Some people are perfectly comfortable with the language of genetics. This is aimed the rest of the world - people who are interested, and who might recognize a word like "heterozygous," but maybe can't quite remember what it means, let alone how to pronounce it. As much as possible, I am going to try to avoid the geek speak, though some is just unavoidable . . sorry.

Almost everyone is aware that living things have DNA, the amazingly detailed instruction manual for what they look like and how they function. Interestingly, almost all living things have two copies; one that came from the female parent, and one from the male.

A trait is anything you can observe about an animal. The particular segment of DNA that codes for a particular trait is called a gene, and the specific place where that segment is located is called a locus (plural, loci).

With me so far?

Some genes come in more than one form. The correct term for the various forms is "alleles," but for some reason, there seems to be some confusion here. Most folks use the word "gene" when what they really mean is a specific form of the gene (example, "the Chocolate gene"), and just for simplicity's sake, I will bow to common usage and do the same.

Most of the time, when genes have more than one form, and an animal inherits one form of the gene from one parent, and another form from the other, you only see one form getting expressed. That's referred to as dominance. When assigning letter symbols to represent genes, the most dominant one gets written as a capital letter. Recessive genes take a back seat to the dominant ones; for a recessive gene to get expressed, it has to be the only form present (or at any rate, there can't be any more dominant forms present).

Please note: "dominant" and "recessive" refer to how the genes interact as far as expression, they have nothing to do with how likely a gene is to be inherited. If an animal has one copy of a dominant gene, and one copy of a recessive gene, both genes have an equal chance of getting inherited. A dominant gene is no more likely to get passed on than a recessive one; the only difference is that you can always tell who gets the dominant one because you see it; you will only see the recessive if it came from both parents.

We are talking about coat color here, and there are a bunch of genes that influence coat color. It is the combined effects of all of them that results in the color we see. Basically, every animal has the potential to produce two pigments; a yellow/red pigment (pheomelanin) and a black/brown pigment (eumelanin). You know how a little bottle of yellow food coloring looks red? That's how pheomelanin works; it looks yellow when there's just a little bit of it, and looks red when there's a lot of it. Eumelanin does the same, to a degree - normally, it looks black, but thin it out a little, and it can look brown, as it does on the Siamese Sable.

There's another way that eumelanin can look brown; you can change the actual shape of the pigment granule so light plays on it differently. That's what the Chocolate gene does, and that's the first gene we will discuss here.

It's often called the B locus, and it's a good place to start, because there are only two forms of the gene. The dominant form (designated B) creates round pigment granules that layer in such a way that hardly any light passes through the hair shaft, and it appears black in color. The recessive form, b, creates oval granules that allow a little bit of light to pass through, giving a chocolate brown color to the hair. B and b interact in the classic pattern of dominance; as long as an animal has even one copy of B, whatever eumelanin is in its coat will be the round granules that look black in color. An animal must have two copies of the recessive form b in order to show the color known as Chocolate.

So:

BB - black
Bb - black
bb -chocolate

Another gene that has only two versions, which interact in the classic way, is the dilution gene, D. The full color form (D) allows both the yellow and black pigments to do whatever the other genes tell them to do, with no interference. The dilute form (d) restricts the amount of both pigments that go into the hairs, and also causes the pigment granules to clump together, allowing more light to pass through. Thus, a Black rabbit becomes a Blue, a Chocolate becomes a Lilac, a Siamese Sable becomes a Smoke Pearl, etc.

DD - full (dense) color
Dd -full color
dd - dilute

So, how do you know the difference between a DD and a Dd? Just looking, you can't tell. If you have a pedigree, you may see that the Black rabbit had a Blue father, and since the only thing a Blue has at the D locus is dilute (d), you know that the rabbit had to have inherited dilute from him. Or your Black doe may deliver Blues in her nest box - once again, the only way you can see dilute is if the rabbit has two copies (dd), and the only way it gets two copies is one from the mother, and one from the father - so now you know that she must have a gene for dilute, since her babies had to get one from her.

I suppose this is as good a moment as any to introduce the "alphabet soup." You may have seen notations like this on other discussions about color genetics, or maybe written on the margin of a pedigree:

aaB_C_ddE_Enen (that's a Broken Blue, by the way).

It's a brief way of noting what you know about the color genes a rabbit has. If you don't know what a gene is, you leave a blank; someday you may see something in a nest box that allows you to fill those in. There are a few other genes that influence color, like Vienna and Wide-band, but most people just leave them off unless they are talking about a color that particularly involves them.

So far, we have talked about the genes at the B locus and the D locus; nice, easy genes that only have two forms. Now things get a little more complex; let's look at the A locus - the pattern genes.

The most dominant form in the A series is the Agouti gene (A). Agouti is the wild-type coloration; white on the belly and underside of the tail, lacing on the ears, light rings around the eyes, light edging around the nostrils, under the jaw, and between the toes. The body hairs on an Agouti-patterned animal have light and dark bands on them; the coat usually has a ticked appearance, and when you blow your breath into the coat, you see rings of color, like a target (typically, dark at the tip, light in the middle, and blue-gray next to the skin).

The most recessive form in the A series is the Self-patterned gene (a). Being the most recessive, the only way you see it is if it is the only form present (aa). A typical Self patterned rabbit is one solid color from nose to tail; if we use Black as an example, he is black on his belly, black in his ears, just all over completely black. He may still have yellow pigment in his coat, but you can't see it, because the black covers it up. Self-patterned animals sometimes are a lighter color next to the skin, but they fade gradually from one shade into the other, while Agouti-patterned animals have clearly defined bands.

And here's where things get interesting - there is a third type of pattern gene; the Tan gene (at). Tan has the solid body color of a Self, with the light colored "trim package" of an Agouti - ear lacing, eye rings, light belly, etc. And just as the appearance of a Tan is intermediate between an Agouti and a Self, that's just where it falls in the order of dominance, too. Tan is dominant to Self, and recessive to Agouti. So, if you have a Tan-patterned animal, you know it doesn't have an Agouti gene, but you can't rule out the possibility of a Self gene unless it comes from a long line of Tans (or you never get Self patterned babies, even when breeding to Selfs).

This is called a "ladder of dominance:"

A - Agouti
at - Tan
a - Self

The gene at the top of the ladder is the most dominant, the gene at the bottom is the most recessive, and anything placed in between is dominant to those below, and recessive to those above. The rabbit will express the most dominant gene it has, so if you are looking at a Self, you know it can't have either Agouti or Tan, or that's what it would look like.

This seems like a good place to take a break; clear so far?

 

[Bunnylady]

Now we tackle a rather complicated group - the C series. For starters, there are 5 (some say 6) different forms. Here we go with the ladder of dominance again:

C - full color
cchd - Chinchilla
(cchm - Medium Chinchilla)*
cchl - Light Chinchilla, aka Shaded
ch - Himalayan
c - Ruby-eyed White

*Medium Chinchilla may or may not exist. It's possible that someone may have seen an interaction between a couple of other genes and gotten confused; most don't mention it at all, so I'm not sure, the jury may still be out on this one.

The most dominant form in this series, the full color C, acts like any other dominant gene - if it's there, you will see all the black and yellow that the rest of the rabbit's genes allow - no changes there. The most recessive form, the REW gene c, is fully recessive; the only way a rabbit can be a REW is with two copies of it (cc).

The second most dominant gene in this series is the Chinchilla gene. Chinchilla takes almost all of the yellow pigment out of the coat, and a tiny bit of the black pigment. An Agouti-patterned Chinchilla looks black and white (this color was called Chinchilla because it resembles the color of the rodent with that name); you can easily see the lack of yellow in the coat, but you probably won't miss the little bit of black. On a self-patterned Chin, the loss of black pigment is visible, though you might have to put one next to an honest-to-goodness Self Black to see the difference. Another clue is the eyes; though the eyes of a Chin may be brown, they are often marbled or gray. If you have a black rabbit with gray eyes, it's a self-patterned Chin. The difference between a Silver Marten and an Otter is the Chin gene; if you sit a Silver Marten next to an Otter, you will see that not only is the little triangular patch behind the ears a different color, but the black of the body is not quite the same.

Okay. Deep breath. Nobody panic here, but from the Chin on down on this ladder, the genes can look different, depending on what the other c-series gene in the pair is.

For example, if someone bred an American Chinchilla to a New Zealand White, one of the possible results is sometimes called a "Ghost Chin." You get the usual Agouti pattern dark band at the tip of the hair shaft, but the normal blue-gray color next to the skin is missing; the rest of the hair is just white. That's the interaction between the Chin gene and the REW gene (cchdc).

The next gene down on this ladder is the Shaded gene, cchl ("chl" stands for "light chinchillation;" they really should have been more creative in the naming). Shaded takes all of the yellow out of the coat, and some of the black as well, but it does it in a certain way. Shaded is somewhat temperature dependent; the areas on the rabbit that are cooler get more pigment, the areas that are warmer get less, so you wind up with a rabbit that is darker on the parts that are cooler (ears, nose, feet, tail) and lighter on the body. Sometimes, an Agouti-patterned Shaded can look like a Chin, but if you look closely, you can see that the dark areas are a really dark brown color, and the color on the body is significantly lighter.

The effect of the other c-gene really shows up with a Shaded. Two copies of the shaded gene (cchlcchl) is a Seal, a very dark brown animal that is even darker on the points (once again, you might have to put it next to a real Black to spot the difference). One copy of shaded, and one of either Himi or REW (cchlch, cchlc) is a Siamese Sable, though the cchlc is usually a bit lighter on the body than the cchlch.

The Himalayan gene (ch) was first noted in the Himalayan rabbit, which also gave the color to the Californian breed. There are several other breeds that may come in this color, where it may be called a Himi, a Cali, or a Pointed White. Himi's have pink eyes, being very nearly albinos. Himis produce no yellow pigment at all, and only very limited quantities of the dark pigment.

Himi shows the temperature dependence at its most extreme; the "points" are very dark, and the body white. Himi kits are born white; it's only as they get a bit older and the extremities get a bit cooler that the dark pigment begins to show up. Conversely, if a Himi kit gets chilled as it grows, it may develop a dark band at the part of the hair that was growing at that time. This banding could almost make a Himi kit look like a Chinchilla, except of course, that the eyes of a Himi are red. The band will grow out with the next molt, but the tendency to put dark pigment in the hair when skin gets chilled remains; does often have dark patches on their dewlaps from fur pulling, and the dark points often get larger during cool weather, and shrink in area during the summer.

There is visible interaction between Himi (ch) and the only c-gene more recessive, the REW gene (c). The chch Himi will have larger, darker points than the chc; while the chch may have a dark patch that goes nearly up to its eyes, the chc may have just the nose covered by the facial marking.

And of course, at the bottom of the ladder is the Ruby-eyed White. It's a true albino, producing neither pheomelanin nor eumelanin, but don't let another rabbit person catch you calling it an albino; it's just not done. What can I say, rabbit people are weird . . . .(smh)

Because the REW has no pigment, it can be really confusing in a breeding program - it has something at the A locus, and the B, and the D, etc, you just can't see it, so you may get some real head-scratchers showing up in the nest box when you breed to a REW. REW's can be great for showing, though - they can't have mismatched claws, or too many stray white hairs (how could you tell??), or any other color fault, so you can concentrate on type and not worry about the rest of it.

REW is sometimes blamed for putting white claws or white hairs on a colored rabbit, but that's not how it works. A REW animal might happen to have the gene that causes the white claws, but you can't see it, since that animal has no pigment anywhere anyway. When you breed this animal to one that has color, it might pass the gene on to its offspring, and since they have color, you can now see the mismatched claws, but that isn't caused by the REW gene itself. If you have a REW that comes from a line of colored rabbits that don't have the white claws, then its offspring aren't suddenly going to turn up with white claws, just because they have a REW parent.


. . . . and now I am getting a break in the rain, so I'd better try to get some work done outside before I try to take on the E series.

 

[frustratedearthmother]

This is awesome info - and I don't even breed rabbits. You are truly a wealth of information!

 

[Bunnylady]

This is awesome info - and I don't even breed rabbits. You are truly a wealth of information!

Aw, thank you! It's a lot to get through; my question is, is it understandable? Or do you have to know what I mean to know what I mean, knowwutImean?

I feel like I'm kind of racing through this, but this is only intended as an introduction; shoot, whole books have been written about this stuff!

Now let's look at the E series:

Es - Steel
E - Normal extension
ej - Harlequin
e - non-extension

There are some crazy players in the E series. The first thing you may notice is that there are two forms that have been given the capital E designation. Normally, the capital letter is only given to the form that's most dominant, and usually, that's the form that is found in the wild-type coloration. When the researchers who were first working out rabbit color genes started on the E series, they gave the big E to the normal extension gene, thinking that it was the most dominant. When they stumbled onto Steel, they found out that it was even more dominant, but they had already assigned the capital E, so this is what we wound up with. Somehow, with this gene, it fits. If you read books on coat color genetics that were written 50 or 60 years ago, you may see references to yet another gene, Dominant Black, but that might just have been Steel, doing its thing.

If you think about a rabbit hair as being first dipped in yellow pigment, and then dipped into black, it might help you understand how the extension genes work. Normal extension (E) allows the black to extend as far down from the tip as the rest of the color genes let it, which means it covers up some, or even all, of the yellow that was put on during the first dip. Non-extension (e) pushes back, refusing to allow the black to "extend" past the tip, which in turn exposes a lot of the yellow pigment. On an Agouti-patterned rabbit, non-extension turns a Chestnut into an Orange, though there is often a bit of "smut" where there is just a tiny bit of black on the tips of the hairs. A Self-patterned rabbit has a great deal more black pigment, and non-extension isn't quite able to deal with all of it, which is why a Tort (short for Tortoise, or Tortoiseshell) has black shading on the points.

In the middle of this ladder, we find Harlequin (ej). With Harlequin, some hairs have no dark pigment at all, while others are flooded with dark pigment. These hairs are usually found in same-color clumps, but there are modifiers that determine just how big those clumps are. In the Harlequin breed, the preference is for really large patches of the same color, while in the Rhinelander, the patches are much smaller.

Harlequin (ej) is dominant to non-extension (e). The interaction with normal extension (E) is a bit more complicated; when a rabbit has one copy of each (Eej), you may see darker patches on an otherwise typical Agouti pattern, especially on the belly.

And now we come to the true oddball, the Steel gene. I have always heard that you can't see Steel on a Self, and though some might argue otherwise, I see no reason why that shouldn't be the case. Steel acts in the opposite way to non-extension; it pushed more dark pigment onto the hair shaft, covering up a lot of the lighter band on Agouti-patterned animals. Here is where it gets truly weird - you really only see the classic Steel appearance when Steel (Es) is combined with normal extension (E). The EsE rabbit looks like a very dark Chestnut; you may or may not see dim versions of eye rings, ear lacing, etc; the belly may be light or it may be dark. The body hairs only have a small amount of the lighter bands showing. When Steel is the only E-series gene present (EsEs), you get a solid black rabbit, to all appearances identical to the Self black. Some people call this a "Super Steel." When combined with either the harlequin gene (ej) or the non-extension gene (e), Steel can appear solid black, or it may have just a little bit of ticking, and the ticking may not appear until the rabbit is mature.

 

[Tale of Tails Rabbitry]

Thank you, @Bunnylady! This should be pinned at the top of the this forum!

 

[Bunnylady]

Well, for a long time I've been thinking that we needed something like this somewhere on this site, and this unrelenting rainy weather has given me an excuse to give it a shot . . . .

Okay, that's the worst of it; we're in the home stretch now. Just a few more genes to get through. Shall we start with the genes that can put white spots on a rabbit?

Probably the first of that sort that we should look at is Dutch (Du). Most people recognize the white blaze, white band across the shoulders, and white back feet of the Dutch rabbit. For a long time, there were thought to be a whole bunch of Dutch genes, and the idea was that you just had to get the right combination of them to get a good Dutch pattern. Now, people seem to think there are fewer, perhaps as few as two; Normal, non-patterned Du, and the Dutch pattern gene du. Even though the pattern gene is considered recessive, a rabbit that only has one pattern gene (Dudu) will often show a partial pattern; it may be no more than a little bit of white on the face and feet.

Another very common spotting gene is the Broken gene, which was first identified with the English Spot (which is why it is denoted as En). Broken (En) is dominant over solid (en), so if it's there, you generally will know it. Broken has a wide range of expressions, thanks to some modifying genes; with the right modifiers, you can get the precision of the English Spot pattern, while without the right ones, you may get a colored rabbit with just a little bit of white on the face, the feet, and maybe the chest (sometimes called a "booted" Broken). A "good" Broken has only one copy of the Broken gene (Enen); two copies (EnEn) results in an animal that is mostly white, with very little color. If the EnEn rabbit has a nose marking at all, it is often just a little spot on the upper lip. Someone thought that looked like the painted-on mustache of silent film star Charlie Chaplin, and the EnEn rabbit has been known as a "Charlie" ever since.

Unfortunately, the gene that creates the Broken pattern isn't just involved in coat color; it is also involved in the development of the digestive system. A rabbit with two copies of Broken (EnEn) can have major problems with its intestines, which may result in a lot of suffering and an early death. Because of this concern, a lot of rabbit breeders avoid the risk of creating Charlies by only breeding Brokens to solid-patterned rabbits.

Another gene that can cause "white noses and toeses" is the Vienna gene (v). Two copies of Vienna (vv) is a completely white rabbit with cornflower blue eyes - the Blue-eyed White. One copy of Vienna, (Vv) usually results in a colored rabbit with some white on it, which is referred to as Vienna Marked. Vienna Marked (VM) rabbits may just have a tiny bit of white on the nose and/or feet, or they may have white markings that are surprisingly similar to the Dutch pattern (though the blaze is often pretty crooked). VM may have blue eyes, brown eyes, or even one of each. Sometimes, there are animals that have the Vienna gene, but show no sign of it; these are called Vienna Carriers (VC).

Silver (si) produces white and white tipped hairs mixed in with the colored hairs in a rabbit's coat. Rabbits with silvering are born solid colored, and develop the silvering as they mature. The dominant gene in this series, Si, produces a solid colored coat without the silvering.

Wide band (w) acts a bit like non-extension, in that it creates a wider light-colored band in the middle of an Agouti-patterned hair shaft. When combined with non-extension (ee), it can push dark pigment off the body hairs completely. Wide band will also put red/yellow pigment onto areas of the coat where it doesn't normally appear, like the belly. Tan (the breed) rabbits need wide band (ww) to give them their red bellies. Completely red rabbits, like the Thrianta and the New Zealand Red, also have the wide-band gene.

Often associated with wide band are some little "helper" genes called rufous modifiers. The rufous modifiers cause the rabbit to produce more red/yellow pigment, making the coat a deeper shade of red. Rufous modifiers are usually indicated with plus signs (++++). The Rufous Gang doesn't always hang out with wide band (w); the Rex breeds employ them to turn Chestnut into Castor. The Red Rex has a red belly, so it has wide-band; the Red Mini Rex has a light colored belly, so it has rufous but no wide band.

There's another color gene that I know of, but those of us living in the U.S. will probably never see it. A rabbit with this gene has yellow pigment, but not the dark; the result is what is sometimes called a "lutino" - an animal with a yellow/red hair coat and red eyes. This has been seen in rabbits in Europe, but as far as I know, it hasn't "crossed the pond," so American rabbit fanciers are unlikely to encounter it.

Have I missed anything? I think that's pretty much it.

So how do you use this to figure out what color rabbit you are looking at? Well, you go about it one step at a time. For example, you ask yourself, "do I see ear lacing, eye rings, etc, and banded/ticked body hairs?" If the answer is "yes," you are looking at an Agouti patterned animal. If it's, "eye rings and ear lacing, yes, but no banding on the body hairs," then the rabbit has the Tan pattern, and if it appears to be the same dark color with no banding or light markings in the ears, etc, then it's a Self. You do that for each gene, and then add up the results. If, for example, you don't know that a Dilute Chinchilla (A_B_cchdcchdddE_) is called a Squirrel, that's OK, but being able to see that it's Agouti pattterned, with no obvious yellow pigment and blue rings rather than black and (probably) gray eyes at least lets you know what you are dealing with genetically, and what you might see if you breed that beast.

Any questions?

 

[promiseacres]

@Bunnylady this is an excellent overview and I believe it's easy to understand even for someone not familiar with color genetics. Good Job!

 

[Gingerpool]

@Bunnylady Where does Lynx fall into the gene pool? Also is otter in a rabbits genes?

Thank you so much for putting this up. I didn't know genes very well before and now... I feel like I can actually do some planning with breeding my rabbits instead of randomly putting rabbits together and hoping for certain colors.

 

[Bunnylady]

Lynx is a dilute chocolate Agouti; A_bbC_ddE_

Otter is the most basic of the Tan pattern colors:

at_B_C_D_E_ - Black Otter
at_bbC_D_E_ - Chocolate Otter
at_B_C_ddE_ - Blue Otter
at_bbC_ddE_ - Lilac Otter

Silver Marten is Otter plus Chinchilla:

at_B_cchd_D_E_ - Black Silver Marten
at_bbcchd_D_E_ - Chocolate Silver Marten
at_B_cchd_D_E_ - Blue Silver Marten
at_bbcchd_ddE_ - Lilac Silver Marten

To turn an Otter into the color of the breed called Tan, you add wide band and rufous. Every rabbit has to have something at the W locus, but since very few colors involve wide band (w), most rabbits don't have that gene, so it's usually just left off.

at_B_C_D_E_W_---- - Black Otter
at_B_C_D_E_ww++++ - Black Tan
at_bbC_D_E_ww++++ - Chocolate Tan

There are some breeds that allow Lynx to have some color on the belly (usually described as a light or creamy tan), so it sounds to me as if for them, Lynx may involve wide-band as well.

 

[Pastor Dave]

@Bunnylady, I can't even imagine the time it took you to write/think this all out. Remarkable