# Grey gene



## SunnyDraco (Dec 8, 2011)

Grey works like a blanket of snow, the foal is born a base color and stands in a slow but fairly steady snowfall as it ages. The foal's coat color is covered over time by the white covering until a horse is visually covered by white hairs. Under a grey coat, the horse is genetically a different color, which is why a coat color calculator needs to know what color a horse was before going grey. 
If you have a grey mustang who was already well into the greying process when you adopted, you would have to pull hairs and test for basically every coat color and modifier to determine the genetic color under the grey. 

When breeding a grey horse, the chance of a grey foal depends on whether or not the grey horse is heterozygous grey or homozygous grey. A heterozygous grey horse has 1 copy of grey, you get a 50% chance of a grey foal when breeding to a non grey. If you crossed two heterozygous grey horses, you have a 75% chance of grey and a 25% chance of non grey. If you breed a homozygous grey, the horse has 2 copies of grey and 100% of offspring will be grey regardless of what color of horse they are bred with. 

Greys can be any color before starting the greying process and will eventually go completely white by the end of the process (the length of time grey takes to finish the process varies from one horse to another, anytime between 4 years old to 20 years old is normal for greys to finish greying out). The pintos that inherited grey will eventually only have their white pinto spots visible while drenched with water so you can see the pink skin under the white markings and the black skin where the grey removed the color pigment.


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## DraftyAiresMum (Jun 1, 2011)

Grey is like a blanket that will cover and hide all other colors. It doesn't care what the base coat or any dilutions of the original coat were. 

In order for a horse to be grey, one parent must be grey. Grey doesn't hide. It's called a simple dominant because if there's one copy of the gene present, it will turn the horse grey. 

Now, as far as calculating color...it depends on the zygosity of the grey parent. If one parent is heterozygous grey and the other parent is not grey, the foal has a 50% chance of being grey. If the grey parent is homozygous grey, the foal will be grey, regardless of what the base color is. If both parents are heterzygous grey, the foal has a 75% chance of being grey and a 25% chance of being not grey. If both parents are homozygous grey, then the foal will be homozygous grey as well.

All horses grey out at a different rate. Theoretically, given enough time, all greys will eventually end up white. I say "theoretically" because sometimes the horse dies before it reaches the pure white state. There are all sorts of theories about how different "types" of greys go grey, but the simple fact of the matter is that no one really knows. Some say horses born bay are more likely to go rose grey, then dapple grey, then fleabitten. Others say all horses born chestnut will skip rose and dapple and go straight to fleabitten. Really, it's anyone's guess.


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## DraftyAiresMum (Jun 1, 2011)

SunnyDraco said:


> Grey works like a blanket of snow, the foal is born a base color and stands in a slow but fairly steady snowfall as it ages. The foal's coat color is covered over time by the white covering until a horse is visually covered by white hairs. Under a grey coat, the horse is genetically a different color, which is why a coat color calculator needs to know what color a horse was before going grey.


This has got to be the most epically eloquent description of the greying process I have ever had the pleasure to read! 

:bowwdown::bowwdown::clap::clap::loveshower:


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## ApuetsoT (Aug 22, 2014)

there's also thought to be some undiscovered genes associated with grey that effect the rate and pattern of greying. Like why some dapple and some go fleabitten. Why some are white by the time they're 4 and other grey into their teens. I think there is a line of Arabs that are associated with rapid graying that makes their manes retain their colour while they are white in the body, and there is a warmblood line that has extremely slow greying. So it's not always easy.
_Posted via Mobile Device_


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## mustangmaiden (Jan 27, 2016)

Thanks for the answers! It's making more sense now. My mustang (I don't own him anymore) was brown when I got him, and at first he would be brown in the summer and then silver-y in the winter, or was it the other way around? I can't remember, it's been a while. But eventually he was just dapple grey all the time and had black legs. I never realized when I had him that he would eventually be white, it's funny to think about and try to imagine him with all white hair. My little sister likes grey horses, and white horses (not sure if she knows that grey hair goes white), and I love andalusians and I know that most of them are grey, and I couldn't take not knowing how grey worked anymore! 
I'd love to have another grey horse someday, and it seems like most of the mustangs you see on the BLM page are grey. Maybe one day I'll have another!


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## mustangmaiden (Jan 27, 2016)

Wait.. I thought of another question.
If you bred a non grey horse (bay, palomino, sorrel, etc.) to a homozygous grey horse, the foal will 100% grey out, BUT, what color will the foal be born as/be before it greys out?


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## DraftyAiresMum (Jun 1, 2011)

mustangmaiden said:


> Wait.. I thought of another question.
> If you bred a non grey horse (bay, palomino, sorrel, etc.) to a homozygous grey horse, the foal will 100% grey out, BUT, what color will the foal be born as/be before it greys out?


It depends on the base genetics of the parents.


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## ApuetsoT (Aug 22, 2014)

mustangmaiden said:


> Wait.. I thought of another question.
> If you bred a non grey horse (bay, palomino, sorrel, etc.) to a homozygous grey horse, the foal will 100% grey out, BUT, what color will the foal be born as/be before it greys out?


It will be born what every the foals base colour would be based on it's parents genetics. They are typically born their "adult' colour, rather than the light baby colours(lightened legs, off shades, ect), but not always. Some will have slight greying around the eyes even("goggles").

So a chestnut and a **** grey with chestnut base would produce a baby that comes out looking chestnut, but will go grey.
_Posted via Mobile Device_


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## Smilie (Oct 4, 2010)

grey is not a color gene. It a a color modifying gene, which causes pigmented hair to be replaced with non pigmented hair
It is also an autosomal dominant gene, meaning a horse only has to have one copy in order for that greying gene to be expressed
If the grey parent is heterozygous for the greying gene, then there is a 50/50 chance the offspring will be grey
The rate of expression also varies, with some horses greying slowly over time, thus not becoming completely white until later in life.
Others, as in the case of my horse Charlie, can have a very rapid progression. She was born a chestnut Appaloosa, large blanket, blaze and four high stockings
By the time she was two, she was white


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## stevenson (Sep 12, 2011)

I had three greys, a TB flea bit red, white in the winter and his flea bit red marks showed in the summer , up until the day he died at age 33. Same for an Arab mare I had that was in her mid 20's . My quarter that greyed was a red roan and in summer he was the same color as winter basically white with a darker grey mane and tail with some red in it. He died when he was 10 , he developed sever copd.


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## Smilie (Oct 4, 2010)

stevenson said:


> I had three greys, a TB flea bit red, white in the winter and his flea bit red marks showed in the summer , up until the day he died at age 33. Same for an Arab mare I had that was in her mid 20's . My quarter that greyed was a red roan and in summer he was the same color as winter basically white with a darker grey mane and tail with some red in it. He died when he was 10 , he developed sever copd.


 Yes, the greying gene will give different appearances, as it works on that base color, and that shade, resulting from interspersion of none pigmented hair, with give different shades, based on that base color, which is quite natural, as white hairs mixed with a black hair coat are going to be different then those mixed with a red based coat
Thus , we have terms like 'steel grey' and 'rose grey', ect


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