Nov 192010
 

By Patty Wilber  

The Eumelanin gene*and the Agouti gene** control red, black and bay coat colors in horses, as described last week.  

The Cream gene can modify the base colors and controls the production of the buckskin and palomino colors, while the dun gene creates a different modification  of the base colors resulting in dun, red dun and grulla colors.  

Buckskin and dun are sometimes confused, because they can look alike in some respects.  They are, however, controlled by different genes.  

Each horse has two versions of every gene (one from its mom and one from its dad) and the Cream gene (Cr or cr) is no exception. Thus, any individual horse can be “cr cr”, “Cr cr” or “Cr Cr”.  

But what is the effect of that? The Cr version causes dilution of the base colors, and the final result depends on how many Cream genes a horse has and what the orginal base color was.    

If a horse has only the “normal” (cr cr) versions, there is no change of the base coat color.  

A sorrel horse  (chestnut, red) with one copy of the Cream gene and one normal version (Cr cr) becomes a palomino. The red is diluted to gold and the mane and tail become white.    

  

Genetically, a chestnut is eeAA, eeAa or eeaa.  “ee” = red and the Agouti gene has no effect, so we can write its genes as ee__, with the blank showing that any of the Agouti versions can be present and the horse is still red.  If we add a single “Cr”, we have ee___Crcr, and this is a palomino.    

A palomino parent has a 50% chance of giving the “Cr” version (the dilution factor) to its offspring and a 50% chance of giving the “cr” (normal-no dilution).   

This brings me to Longshot.  His mom is a palomino: ee__Crcr (a red horse that was diluted)  His dad is a chestnut: ee__crcr.  From his dad, Longshot got e_cr.  From his mom he got e_cr.  So, Longshot is ee__crcr = red.  Longshot does not carry the Cream gene.  He cannot pass the Cream gene on.  If a red  horse has the Cream gene, you can see it in the coat color; it is never hidden.    

Note: Longshot is still sore on his bad leg, but it has uncurled!  He also has a cold, so he’s a little droopy.  

Longshot has a full sister, Squirt.  She is a palomino.  Where did she get the Cr gene?  From her mother!  

When the Cr gene is found in a horse with a bay base coat, the result is a buckskin.  A gold body with black mane, tail, legs, ears.  The red of the body is diluted to gold, but the black is not affected.   

 
 I recently bought a buckskin filly (Lacey).  Her mother is a buckskin and gave Lacey the Cr gene.  Her father is a red dun, but he did not pass the dun factor on–darn!  A dunskin would have been cool!
 

JJM Spurs Zan Lace at a few hours in the first shot and 5 months in the second. She is a buckskin (E_A_Crcr) but she is also very "sooty". The sootiness is controlled by yet ANOTHER gene!

 

 If I bred my buckskin filly to Tabooli (a palomino), the result could be a horse that is a double dilute (25% chance).  CrCr.  They are nearly white in appearance, as the base color is double diluted!    

    

A black horse with a Cream gene results in a color called smoky black, but it can be a bit tricky to identify visually.    

    

To have your horse tested for the Eumelanin, Agouti or Cream genes, try UC Davis!    

The Dun Factor is controlled by a dominate allele.  Horses that are “DD” or “Dd” have dun characteristics, but horses that are “dd”, do not.    

A red base color horse (ee__) + the Dun Factor (DD or Dd) produces a red dun.  Red duns have a reddish gold body, with darker red legs, mane and tail and ear tips.  In addition, they have a dorsal stripe that extends into the tail, stripes on the legs and sometimes a stripe on the withers.  Penny is a red dun.    

(This is not Penny)

 

 A bay base color horse (E_A_) + the Dun Factor results in a dun.  Duns have a body color that ranges from gold to reddish brown with black points.  In addition, they have a black/ dark dorsal stripe, black stripes on the legs and sometimes a stripe on the withers. Duns are frequently confused with buckskins (but they lack the leg barring and dorsal stripe), and you can see why in the picture below    

     

A black base color horse (E_aa) + the Dun Factor produces a grulla.  The dorsal striping and dark points are evident but the body is a silvery color.  It is very striking!    

    

The American Buckskin Horse Associaton registers  duns, red duns, grullas and buckskin, but not palominos or double dilutes.     

Can a horse be both buckskin and dun?  Yes!  Hollywood Dun It was. I was hoping my new filly Lacey would have both because when bred, a dunskin would be a higher percentage color producer!  A horse could be a palomino and a dun, too!    

Dunalino

 

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*Eumelanin gene:  “E” version-the horse can make black pigment and “e” version-the horse cannot make black.     

**Agouti gene: “A” version-if the horse has black, the black is restricted to the legs, tail, mane and ears and the”a” version-if the horse has black, it is allover–it is not restricted.

  • Joan

    Nice! Very informative. So then how does the Lipizzan/Andalusion gene’s work? Starting off as a foal some form of the base color ? Then turning white…. D’art was very Bay looking with black mane & tail and Shidoni was more of a dun color. Then they both turned to grey then white.

  • Richard Hall

    All I ever wanted to know about horse colour and was very very afraid to ask.

  • http://wynnsfollymini.myhosting.net/Albums jlh

    ah, fun with colors
    before you get into patterns, are you going to finish off the modifiers?
    like the many shades of grey?
    I’m sure you aren’t as used to dealing with the silver gene in western stock horses as we are in some other breeds.
    but to address the question from Joan, a greying horse is one whose coat ages to grey, whatever the base coat was – think in human greying terms, only usually faster.
    a silver, on the other hand, is a modifier that works like the cream gene does, only on the black instead of the red colors.
    you can’t see it on a red horse, a silver bay is red with a white-(ish) mane & tail, and a silver black has a grey colored body with the white mane & tail.
    (I have a three year old gelding who carries both the dun and silver genes.
    I also have a perlino filly whose father was a silver modified buckskin, and her mother was palomino.)
    the other “grey” would be a blue roan a fairly stable color of blue/grey with a darker mane & tail.
    the website link above leads to my albums of horse picture with many color variations, if you want to use any for examples.

  • http://www.doranna.net Doranna

    Joan, the Lippi grey is the same grey as any other breed…it’s just so prevalent as to be a breed trait.

    (I seemed destined for greys–my walker mix mare turned the most stupendously gorgeous dapple as she greyed out (I never did figure out what her base coat truly was even when I was looking right at it, the big mystery of my life), and Duncan the Lippi was mostly grey when I got him, but was bay for starters.)

  • Patty

    Hi every one. Gray is a dominant gene GG, Gg = gray and as jlh and Doranna saod, they start out with whatever base color and then gray out–sometimes faster and sometimes slower.

    There is an appaloosa gene, probably the LP gene, that causes horses shed their foal coat and be white. Pink skin under there.

    I haven’t looked into the silver gene much, but am about to click the link and check out the pictures! Have looked at the champagne gene a little bit but haven’t seen a champagne horse in person. I want to see one of those Ak-…forget the name…horses with the super metallic looking coats.

    Roan is also a dominant gene (RR or Rr are roan) but it seems likely based on offsprng outcomes that RR is actually lethal, so all living roans may be Rr. Roans have a dark face (grays have light faces) and there are black, bay or red base color roans–>blue roan, red roan. Roans tend to be roan through out their lives whereas grays get lighter. There is at least one more roaning gene that causes roaning along the rib lines and is less noticiable.

    There is an appy gene that seems to involve roaning, too, but these horses may change a whole bunch in color throughout there lives.

  • Patty

    jlh–can you send your link? It is not clicking thru!

  • http://wynnsfollymini.myhosting.net/Albums jlh

    sure – it is http://wynnsfollymini.myhosting.net/Albums/
    the champagne horse breed you were looking for would be Akhal Teke. ;-D
    I owned a champagne mare once, before the gene was isolated and named.
    didn’t know til years later what she was, and don’t have a good pic of her.
    sadly I have to admit one of my goals in life is to own a horse of every color (my breed specifically says there is no wrong color). we have an overabundance of silvers – and they are supposedly traced to one horse imported in the 1890s, but I think there were others just not recognized.
    we’ve quit breeding, so don’t know how that is going to end up, but other than a true blue roan, a frame overo of any color, a pearl, or a brindle I’ve come pretty close.
    I’ve really enjoyed your horse posts, just haven’t had time to drop in much.

  • Patty

    jlh–thanks for the kind words. Wouldn’t a brindle be a kick–especially if it were a chimera!! I am checking the linik now!

  • Patty

    jlh–I looked! Fun fun photos!

  • jlh

    I hope you enjoy the pictures as much as I enjoy this blog.

  • http://www.doranna.net Doranna

    Patty–one of these days we’ll squint at piccies of my mare and see what we can see re color…

  • Patty

    D–that would be fun!
    jlh-it would be be hard to stop breeding-those foals are precious!

  • b Wilson

    Why are they calling the buckskin dun or the yellow dun a new name “dunskin” People should know that this color of a dun already has a name!