Watering down coat colors for fun and profit

Let's talk dilute genes!  As a reminder, these are: cream, pearl, silver, dun, and champagne.

Cream is notated as Cr (on) and C (off), and it's the one almost everyone is familiar with, even if they don't know it.  That's because cream is the gene that gives us palominos and buckskins!

Chestnut + 1 cream = palomino (taken at a local show)

Bay + 1 cream = buckskin (taken at a local show)

Notice how black's missing?  Black with one cream gene turned on is called smokey black, and it's super hard to tell without genetic testing (or breeding).  A smokey black can look black; it can also look seal bay or almost liver chestnut in color.  It's totally possible I have a photo of one somewhere, but without knowing the test results, I'd have no idea.

Generally, cream is considered one of the genes that primarily affects red areas of the coat.  So chestnuts turn gold and white, and the body of bays turns gold.  And blacks stay dark.

But cream is incompletely dominant (one copy turned on does one thing, two copies turned on does another).  So cream is also responsible for pale, almost white horses with pale blue eyes and pink skin!  Depending on whether they're chestnut, black, or bay, a horse with two copies of the cream gene is called cremello, smokey cream, or perlino.

Pictures borrowed from Wikipedia.  L to R: smokey cream, cremello, perlino

With two creams, you lose most color.  It's still possible to see the difference between the coat and the markings, even if sometimes it requires either a bath or a serious up-close inspection.  Cremellos - chestnut with both cream genes turned on - tend to just look white.  Perlinos - bay with both cream genes turned on - tend to have darker manes, tails, and points.  And smokey creams - black with both cream genes turned on - tend to just be darker overall than cremellos.  'Darker' generally seems to mean 'somewhere between darker yellow and reddish.'

Now, here's where it gets really interesting.

Cream seems to share a gene location with pearl.  Pearl is also called the Barlink factor; it was originally discovered in Andalusians and Quarter Horses separately.  The Andalusian folks called it pearl; the Quarter Horse folks called it Barlink, after the family line where it was found.  Pearl won when the geneticists figured out it was the same thing.  :)  It's also been located in Paints (of course, because of the close Quarter Horse ties), Gypsy Vanners, and Paso Finos (close Andalusian ties there).

Pearl is generally notated as Prl (on) and prl (off), and it's actually recessive.  You have to have two copies of pearl to see the color effects.  A horse with one copy of pearl doesn't show anything.

Well, mostly.  We'll come back to that in a second.

Pearl, like cream, lightens the horse, although it does so more uniformly.  Chestnuts end up kind of a weird pale reddish color, bays similarly go a weird pale reddish color with a much darker mane and tail.  Blacks end up a dark, weird reddish color.  They may also have a unique sheen to their coat, kind of like an Akhal Teke.

Chestnut pearl.  Picture borrowed from Animal Genetics' pearl test page.

If you want to see some really spectacular examples (and some gorgeous photography), check out this link.  It looks like they have at least one chestnut pearl (Sol PM II), at least one bay pearl (Quitasueno VII), and at least one black pearl (Klon), although that's about 48% guesswork on my part!

Now, let's go back to horses with one copy of Prl.  With just the one copy, you won't really see anything.  However, if you have one copy of pearl and one copy of cream, then you get a horse that looks a lot like a cremello, perlino, or smokey cream... but isn't.  This girl is a good example of this (with helpfully provided genetic testing results).

Part of the reason that cream and pearl are thought to share a gene location is because a horse that is CrPrl will only pass down one or the other.  The test results are usually split out, so I'm not sure if the tests for the two are that different or if the scientific community hasn't completely decided that they're in the same spot or what's going on there.

Silver, on the other hand, affects black - not red.  It's also called silver dapple or the wildly inaccurate "chocolate palomino."  Sometimes it's also called taffy, which is just... weird, so I prefer to call it silver.  It's dominant, so you'll see the same effect with one copy or two.  It dilutes down the mane and tail heavily when they're black (ie, black or bay), and it dilutes the coats of black horses.

Chestnuts with silver won't ever show it.  Bays, on the other hand, will actually kind of look like a chestnut with a flaxen mane and tail... until you look closely.

Like this girl - tested out silver bay, but pretty close to chestnut!

Black is where you get what's really the classic silver dapple.

Stock image, blanket permission from photographer to use w/linkback on the image.

Stock image, blanket permission from photographer to use w/linkback on the image.

It's a common color in Rocky Mountain and other gaited horses, and shows up in Morgans and some draft breeds as well.

Silver black horses do tend to darken with age, and the manes and tails of silver bays will do so as well.  We actually have a silver black at the farm - although his color is complicated by varnish roan - so I can show at least some of the darkening over time.  (His mom, the silver bay above, is also still there, but she's pretty static in color at her age.)

A few days after birth.

About 2 months old. I was joking that his registration papers should list his color as 'taupe' at this point.

Around 15 months old

As a 2-year-old

He's three this year, and we're still in the furry stage of late winter, so more photos of him will have to wait for spring. :)

For reasons I do not understand, silver dapple is notated in horse genetics with a z.  Lowercase z for off, uppercase Z for on.  So the boy above is (because I'm cheating and know his genetic results) EE aa zZ LPlp - 2 copies of extension turned on (so black), no agouti (so not bay - still black), one copy of silver (so silver black), and one copy of the Appaloosa gene (so silver black varnish roan).

Also, close-ups of his coat are super fun.  Black + silver dapple + LP roaning = this craziness.

(Oh my god, this is getting long! lol)

Dun is a gene that affects the base colors equally.  It dilutes the body color, leaving a dark dorsal stripe, dark cross on the shoulders, striping on the upper legs, and a dark head and legs.  "Dark" on bay and black means black; "dark" on chestnut means a darker red.  Sometimes you'll see a horse that looks dun, but isn't; some horses just have really dark shading along their spines, but don't have the leg striping.  There's also chatter - which I haven't looked into yet - that there is a gene producing dun that isn't dun, which is the best way I can summarize it.  The discussions I've seen call it non-dun 1 and non-dun 2, which... wtf does that even mean?  So I'm just going to ignore that for now and talk about plain old dun.  It's notated as d (off) or D (on) and seems to be a dominant gene.

I'm lifting some pictures from Wikipedia here, but the best way I've found to see what dun looks like in various colors is to go look up Norwegian Fjords.  They pretty much come in dun, dun, dun, or dun.

Dun on black is called grullo (or grulla), blue dun, or mouse dun.

From here.

Dun on bay can be called just... dun... because why not make things more confusing, but it also goes by bay dun, classic dun, or zebra dun.

From here.

Dun on chestnut is called red dun, claybank dun, or fox dun.

From here.

And because the colors build on each other, you can also get buckskin duns (or dunskins), palomino duns (or dunalinos, a term which hurts my brain so much for some reason), perlino/cremello/smokey cream duns, and theoretically - although I haven't run across one in person - pearl duns and silver duns.

And last but not least - Champagne.  It's dominant, like most of the others, and it's generally notated as ch (off) and Ch (on).  Like dun, champagne dilutes all of the base colors; coat colors lighten, and the horse will go from blue eyes and pink skin at birth to hazel eyes and freckled, pinkish skin as an adult.

On chestnut, it produces gold champagne - which looks an awful lot like a darker palomino!

From Wikipedia, here.

You'll also see gold champagnes with red manes and tails, but this palomino-like presentation is very common.

On bay, champagne produces amber champagne.  It reddens the dark points and lightens the body.

Mare formerly owned by my BO - both the same girl, just different cameras/light conditions.

Different horse, better photo! From Wikipedia, here.

Champagne on brown actually has its own name: sable champagne.  It's much darker than amber champagne, but still has the darker mane and tail and points like bay-based colors do.  This page at the International Champagne Horse Registry shows some good examples.

On black, champagne produces classic champagne - also sometimes formerly known as lilac dun.

From Wikipedia, here.

And like dun, champagne can appear on palominos (gold cream or ivory champagne), buckskins (amber or sable cream), smokey blacks (classic cream), cremellos (gold double cream or cremello champagne), perlinos (amber or sable double cream or perlino champagne), smokey blacks (classic double cream or smokey champagne), red dun (gold dun), bay dun (amber or sable dun), grullo (classic dun)... and can even have silver (amber, sable, or classic silver).  And theoretically pearl as well, although I haven't seen any pictures of one yet.

Champagne is found in most of the stock horse breeds (AQHA, APHA, Appaloosas) and a lot of the gaited horses (Saddlebreds, TWHs, Missouri Fox Trotters, etc).  And almost all American Cream Drafts are gold champagnes.  The thing all these breeds have in common?  They're all American breeds.  So it seems like champagne must have evolved in the US at some point - I've seen a date of 1890, but don't know how reliable that is.

And that ends the non-pattern coat color stuff!  There are definitely theories about other genes that cause specific and unusual coat colors or effects - I mentioned sooty, pangare, brown, and non-fading black, and I've seen stuff about a 'satin' and a color coming from miniatures that's referred to as 'mushroom' - but at this point, I don't know of anything confirmed.  I may come back and do another post on some of that stuff later, because I haven't really talked about the variations of coat color that give us terms like liver chestnut and sorrel.

So at this point, we can say that this:

Ee aa CrC zz DD chch lplp

Is a smokey black grullo.  (Interestingly, I've seen theories that this genetic combination is what produces the super-silvery grullos with the very black head/legs/hair, but I don't know that this was ever backed up with genetic testing.)

Next genetics post starts the non-Appaloosa patterns!  I'm going to break that into three parts, I think: classic paint patterns, roaning patterns, and dominant white.