Dominant white/white spotting

"Dominant white" refers to a large group of genes that produce white spotting in various individuals and breeds.  It's actually one of the areas where they're doing a lot of research, so new dominant white genes are added to the list fairly often.  I'm not sure why everyone's saying suddenly, "Oh, it's white spotting, not dominant white," so I'm gonna stick with the name I learned it was for now.

The expression varies both from horse to horse and from gene to gene; some patterns look like sabino and others produce pure white horses.  But generally, the following things are true:

• Inheritance is dominant - one copy turned on and you can see the pattern.
• All of them are coming from the same areas of the DNA, so they're grouped together and it's assumed you can only inherit one dominant white gene from each parent.
• No horses have been found that have the same dominant white version turned on twice, so it's assumed that they are lethal at the embryo stage.  (There is an exception, which I'll call out.)
• New dominant white genes occur as random mutations, so they often appear suddenly and can actually happen in any breed.
• Eye color isn't usually affected, so unless there's another pattern or coat color acting, the horse's eyes will be normal brown.
• Skin is pink under the dominant white pattern.
• Some versions are a sabino-like pattern, and there's a lot of confusion between sabino and dominant white.
• In version where the horse is mostly white, but still has color, that color tends to be concentrated along the topline, especially the mane and ears.  There may also be roaning or interspersed spots in the white.
• Hooves tend to be light-colored.
• Mostly white horses can sometimes lose the non-white hair over time, eventually turning entirely white.

In the genetic test results, it's generally shown as w (off) or W1-W20 (on, for whichever one you've got).

Yeah.  20.  Maybe more.  I'm going to pull pictures where I can, although of course some of them are just going to be a white horse...

White-1 comes from the Franches-Montagne or Frieberger breed, and specifically from horses descended from the mare Cigale, who was born in 1957.

From the identifying paper, loaded on Wikipedia.

Horses are generally born almost white, and can lose what pigment they have as they age

White-2 is from Thoroughbreds.  They descend from a stallion named KY Colonel, born in 1946.  He's described as having high white stockings and a belly spot, much like a sabino, and passed those genes on to two of his foals.  One, War Colors, was registered as a roan but failed to produce any foals.  The other, White Beauty, passed down her white color to a line sometimes referred to as the "Patchen" line, after the mare Patchen Beauty.

White Beauty, borrowed from here.

According to The Blood Horse, one of the latest generation is Chief White Fox, and it looks like he has some cousins and half-siblings out there.  That said, it's still a small, rare line.

Some presumed W2 horses - War Colors being a great example - have been registered as roan or grey, but the "typical" presentation is all white, just like White Beauty.

White-3 comes from Arabians.  When I was talking about sabino in Arabians, this is one of the genes I was thinking of that isn't sabino, but (confusingly) is called sabino by the Arabian people in a lot of the information I've looked at.  It comes from the line of R Khasper, a stallion born in 1996.

R Khasper, from his owners' page on him here.  Looking good at 18 in the photo!

W3 shows up as high whites and belly spots - or more, all the way up to mostly or all white.  Looking at him and his foals, if there's color on the highly expressed horses, it's tending to congregate around the ears, the base of the tail, and in a downward-pointing triangle on the back between the haunches and withers.  There's a lesser degree of color along the neck, as well.  This is generally true of a lot of the sabino-type dominant whites, but that one triangle was just particularly striking to me!

White-4 is found in an entire breed, the Camarillo White Horse.  It all stems from a stallion named Sultan, foaled in 1912.  According to what I'm seeing, he was a Spanish Mustang, but was crossed to Morgans to form the beginnings of the breed.  Since the white coat is so characteristic of the breed, they do have an open studbook so they can cross out to non-white horses and maintain the color.  (Remember, W4W4 is believed to be lethal in utero.)

And they're pretty much just white in appearance.  At most, they might have a little color along the topline.

Borrowed from Wikipedia.

White-5 is from the Thoroughbreds again, this time descendants of Puchilingui (foaled in 1985).  W5 horses can range in expression from white blazes and high, irregular socks on up to white or near-white horses.

Puchilingui, from here.

Probably the most high-profile example of the line is his son, Sato, but there are plenty of others!

White-6 was another Thoroughbred, but I can't find anything other than this:

From the original paper

According to what little I can find - and squinting at horse e that picture - it's a very roaned sabino-like type, and only one horse was tested at the time the paper was published in 2008.  Speculation points to a horse named Marumatsu Live as the horse in question, but I haven't seen anything but speculation.

White-7 is - stop me if you've heard this one - a Thoroughbred mutation as well.  Again, that one photo above is all I can find (horse f); squinting at it reveals another heavily roaned, sabino-like pattern.  The horse tested has not been identified publicly aside from stating that the dam and siblings were solid and the horse was foaled in 2005, so I've had no luck tracking down anything but speculation about who it is.

White-8 comes from Icelandics.  Equine Tapestry points to the Thokkadis family, although every other source says "unidentified Icelandic;" she does a lot of pedigree analysis to track colors, so while she has been wrong in the details of the genetics, she's generally right in the pedigree department.  Also seeing that noted on another, much more dubious source (it's a random forum, so... reader beware).  Unfortunately, searching Thokkadis and Icelandic doesn't turn up anything substantial other than a picture from the same dubious source as part of a much larger image that I cannot get to load.  Squinting at the photo strip above (horse g) reveals a white pattern that doesn't look all that different from W3 and W5, but the only other image I can find is about as big as the images in that strip and in an image that is horribly pixelated because it refuses to load.

White-9 is from the Holsteiners.  Again, unidentified single individual reported, and again about all I can do is point to that photo strip (horse h).  Similar to W8, I can see there's an alternative image in the picture that will not freaking load, but I can't say much about it.  It's white?

White-10 is much easier to find!  It's from Quarter Horses, specifically descendants of GQ Santana (foaled 2000).

GQ Santana, from here.

Looking at pictures of his foals, that dark eye is characteristic of the maximum expression; it's there in a whole lot of them.  Lesser expressions look more like sabino - high leg white, belly spots, etc.

White-11 comes from a draft breed called the South German Coldblood, and specifically seems to be from the bloodline of Schimmel.  The South German Coldblood is one I hadn't heard of before; it's similar to the Noriker, but has been shown to be genetically distinct.

I found one picture other than the lovely (if tiny) one in the photo strip above (horse l), and I'm not entirely sure where it belongs because it's on Pinterest.  It also shows what I know has to be a young draft, probably 2-3 years old and deep into the awkward stage. Poor baby.  lol

White-12 is yet another unidentified Thoroughbred, and I'll cycle back to the huge number of TBs in this list at the end, because it's interesting.  Suspect forum source says the tested horse is deceased, and I'm not spotting a picture other than the one that won't load.  (Argh, so frustrating!!)  It looks similar to W5.

White-13 is assumed to be from Quarter Horses; it was tested in a single individual or small family of QH-Peruvian Paso crosses.  Again, the image-that-won't-load is the only one I can find, and the horse it shows is... white.

White-14 is another Thoroughbred, but this one's identified!  It comes from a Japanese bloodline, descended from a mare named Shirayukihime.  Like W2, there's a lot of pure white going on here.

Yuki-chan, one of Shirayukihime's foals. From Wikipedia.

White-15 sends us back to the Arabians, and specifically to the Rhocky Rhoad / Khartoon Khlassic bloodline.

Khartoon Khlassic, from his website.

Rhocky Rhoad, from his owners' site.

Again we're looking at a very sabino type of spotting - face white, high white legs, and belly spots.  The most expressive of the foals I looked at had a huge belly spot that extended up onto her body, but most of them look closer to these two stallions.

White-16 was been found in the Oldenburg.  No word on where exactly it came from, but a horse named O' Wie Weiss went through the auctions and and is theorized to be W16 - and possibly her dam as well.

From here, linked off the CotH forum.

However, the actual line wasn't identified in the original papers, so this is only a tentative identification; the dam could easily belong to a known or suspected dominant white line (especially with warmblood lines, where they keep bringing in TBs), or this could instead be sabino-1. 

White-17 is from the Japanese Draft Horse - and again, we're sparse on information here.  It appears that there were two individuals located and tested in 2010, and the breed is known to have facial and leg white and the odd white individual, but... that's all I can find.

White-18 is from a Swiss Warmblood named Colorina Von Hof, born in 2009.  Again, there's a similarity to W5 - and again, the only freaking picture I can find is on Pinterest!  (I kind of hate Pinterest.  It's a neat concept, but it really robs all context from the images, and I'm trying to make sure that if I pull photos from somewhere other than my personal collection or Wikipedia, I can at least account for where it originally came from.)

White-19 is Arabians again, this time believed to come from a mare named Fantasia Vu.

Awestrukk, a descendant of Fantasia Vu. From his owners' site.

Again we've got the flashy sabino, but like the Khartoon Klassic lines, they don't really seem to come in white. Awestrukk there is a bit more flashy than the average, but nicely shows the pattern.  W19 horses sometimes have blue eyes, although it's not clear from what I'm seeing if that's because of the W19 or if there's a separate pattern going on.

There's also this guy, also W19:

HAAP Snowy River, from here. (Also found a source for the same photo that is... entirely in Russian... so we're gonna go for the one I know what it's saying.)

This presentation is atypical for W19, but is typical for this cross - Pandemonium River x  Fantasia Vu.  It's speculated that Pandemonium River carries an additional sabino or dominant white pattern that's adding to the white of W19.

And last but not least is White-20.  And it's the weird one that isn't lethal when two copies are turned on.

Where the others are flashy as hell all by themselves, W20 seems to be more related to simple white markings.  Copies of W20 have been found in horses that have nothing more than a blaze and some socks.

Like these two.  Borrowed from Equine Tapestry.

Looking at pictures, there are examples with even less white.

On the other hand - W20 is one of the only dominant white genes to be discovered in combination with any of the others.  When it does show up with another dominant white gene, it significantly increases the amount of white visible.

Shew of Gold GF (W5) with her white foal Supernatural (W5 and W20).  From Equine Tapestry.

There are more examples here.  It seems to be the oldest of the white genes, and has been discovered in a huge range of horses - Gypsies, Thoroughbreds, Icelandics, Minis...

Now, I said there's at least 20, and I said I'd come back to the Thoroughbreds!  There are the occasional mentions of additional W genes.  One site I looked at talked about W21 and W22, but didn't do much more than cite the name of the paper and a generic copy-pasted description of the paper itself. 

There are a couple of lines of TBs that look either dominant white or sabino, but researchers haven't identified what gene they have.  There's a mare named Turf Club who seems to have spontaneously mutated (speculation is that she's the W7 horse, but again nothing I found confirms this).

Another mare, Not Quite White, produced a stallion named Airdrie Apache that gets a lot of use as the sire of "pinto" Thoroughbreds; speculation is that she's a dominant white as well, with an as-yet-unidentified mutation.  Airdrie Apache definitely passes down his pattern, though!

Airdrie Apache, from here.

White Horse Productions calls out a few more that might be dominant white and might not.

There have been white Standardbreds that, because their parents were solid-colored, might be sabino (if the parents were minimally expressed) or might be new dominant white mutations.  And there's nothing that says there can't be other examples out there that have passed unnoticed.  Various sources I looked at call the gene where dominant white and sabino and some of the other white patterns sit "volatile" - it can and does mutate regularly.

There's also a color called manchado, which appears only in horses with origins in Argentina.  It's sometimes speculated to be environmental - although that does raise the question of why Argentina specifically and only - but it's got a wide enough distribution in enough breeds down there that some have questioned whether it's genetic, even though it can and has been reproduced down family lines.  If so, it seems to be recessive.  Equine Tapestry covers this in pretty good detail here.

From White Horse Productions.

So is manchado dominant white, despite being recessive?  Sabino?  Something else?  No one knows yet.

Ticking along to roan

Next up, roaning patterns!

Roaning is generally defined as areas (up to and including the whole horse) where the horse's base coat color is evenly mixed with white.  Unlike grey and varnish roan, the white hair is usually present when the foal is born, and generally the horse will keep the same amount of white or get darker, not lighter.  A horse with roaning may appear darker in the roan areas in winter and lighter in summer, but the amount of white isn't actually changing as the seasons do.

Classic roan or true roan is written in genetics as rn (off) and Rn (on), and it's a dominant gene - one copy shows the roaning.  The test for roan is... weird... in that it's not testing for the exact gene itself; they haven't identified it.  But they have identified some markers in other places in the DNA that indicate that whatever gene it is is turned off or on and whether one or both copies are on in certain breeds of horse.  The only public test available is for horses with Quarter Horse and Paint ancestry.

The horse's entire body will be roan, although the head, legs, mane, and tail will have much less white than the body.

Red roan. From Wikipedia.

Bay roan. From Wikipedia.

Blue roan. From Wikipedia.

The three most common versions of roan have their own names: chestnuts are red roans (they used to be called strawberry roans, which is the version I learned as a kid!), bays are bay roans (but used to be red roans), and blacks are blue roans.  From there, there don't seem to be specific names, just a color with roan after it.

I've heard that combining true roan and varnish roan doesn't go the way you'd expect - in other words, probably doesn't mean more roaning - but I've never seen an example, so I can't say for sure!

One of the other distinct characteristics of true roans is that they'll have what's called corn spots.  Those spots are places where the horse's skin was damaged somehow; instead of growing back roaned, the spots will grow back the base coat color.

The examples above are pretty clear-cut roans, but it doesn't have to be that way.  Sometimes roan is really, really subtle.

Minimally roaned chestnut, from (oh god) the second year I was taking lessons - 1993 or 1994 - so apologies for the crappy quality.  Actually makes her look more roan than I remember!

One of roan's close relatives is rabicano.  This is one of those patterns that we can see - we can even see that it seems to be dominant - but geneticists haven't discovered the actual gene for it yet.  They do know it's not the same genetics as true roan, though.

Where true roan affects the horse's whole body, rabicano affects the flank/barrel area and the tail preferentially.  It also tends to be more expressed on chestnuts than other colors, although it can and does appear on any color.

From Wikipedia.

With extreme expressions of rabicano, the ribs may be striped (as in the photo).  In minimal expressions, it may just affect the tail.  In all expressions, the white hairs on the tail - often in rings or on either side of the tail head - acts as a defining characteristic of rabicano.  It's often called a coon tail or skunk tail.

From Wikipedia.

Rabicano also tends to spread as the horse ages, and unlike true roans, rabicanos won't have corn spots.  It also shows up in breeds (like Arabians) that don't seem to have true roans.

Sabino - and the dominant white patterns I'll talk about in the next post - are just kind of fun.  It's typically notated as sb (off) and either Sb or Sb1 (on).

Sabino is actually a group of patterns.  The one identified for testing is Sabino-1, but there are sabino-like patterns in draft horses and Arabians that behave similarly but test negative for Sabino-1.

On a horse with sabino, you'll see: roaning at the edge of white areas, which tend to have jagged edges; belly spots; irregular face markings (especially blazes) that may extend past the eyes or chin; two or more white leg markings that typically extend above the knees and hocks; and roaning or random white marks ("lacy" or "splashed" in appearance) on the belly, barrel, and flanks.  Unlike splash, there is no link to deafness.

Sabino is another one that can easily be mistaken for something else - or nothing at all.  The most minimal expressions may just be a chin or lower lip spot; on the other end of things, sabino can and does produce pure white horses (and these are healthy, unlike the pure white frame horses).  I've classed it with roan and rabicano because it does have that characteristic roaning to it.

Sabino-1 is known to be incompletely dominant, like cream.  One copy of the gene turned on produces a horse with the typical sabino markings.

Borrowed from Wikipedia.

Two copies of Sb1 produces a horse that is at least 90% white at birth, with the corresponding pink skin under the white pattern.  This is sometimes referred to as sabino-white, especially when the horse is almost entirely white.

I could argue this guy as homozygous sabino or as sabino/splash.  (From a local show)

"Draft-type sabino" typically shows up in Clydesdales, Shires, and breeds related to those two (like Gypsies).  They actually included examples in the study that identified sabino-1, and none of them tested positive for that version of the gene.  What gene it is, they don't know yet, but it behaves like sabino and is generally assumed to be a sabino pattern.

A draft-type sabino will have white facial markings that range from blazes to bald faces to apron faces, which may wrap around the face and generally have feathery, roaned edges.  If they have white on their forelegs that extends above the knees, it may trail up to the shoulder or back of the leg to the elbow, again with the feathery edges.  White on the back legs, which is common, may extend up the front of the leg to the flank.  Belly spots are also common, especially when the white on the legs extends over the knees.

Very typical Clydesdale with draft-type sabino. From Wikipedia.

Unlike sabino-1, it seems like the draft version is only dominant, not incompletely dominant.  Since Clydesdales and Shires are generally a closed population (they're not registering anything that doesn't have parents of the same breed), there should be about 25% of the population that come out with 90% or more white if the draft-type sabino is incompletely dominant, and they just don't see it.  White Clydesdales and Shires are very rare.

To break down that math, assume you have a foal whose parents are both Sbsb.  Baby has four options for what gene pair it gets: sbsb (both off), Sbsb (one on from dad, one on from mom), sbSb (one off from dad, one on from mom), and SbSb (both on).  Four options, so the chance of any given genetic pair is 25%.  And with sabino-1, they see this: with two Sbsb parents, 25% of babies are solid, 50% are sabino (because Sbsb and sbSb look the same), and 25% are sabino-white.  With draft-type sabino, 25% of babies are solid and 75% are sabino.

Similarly theoretical is sabino in Arabians.  Arabians actually have a couple of dominant white patterns, but they also have white with roaning that isn't explained by those patterns; I'll go into this on the dominant white post, but dominant white is for the most part tied to bloodlines.  If a horse doesn't descend from the founder (assuming they've figured out who it was), it's unlikely that they've got the same pattern.  It's always possible that the horses showing sabino could end up being additional dominant white patterns, but for now they're classed as sabino.  As with the draft-type sabino, there's no genetic test for it yet.

As with other types of sabino, you'll see the face white, belly spots, high whites, and roaning around the spots.  The maximum expression in Arabian sabino seems to be about 50% white instead of 90%, and the few apparently sabino-white Arabians have tested negative for sabino-1.  It's not clear at this point if it's a dominant or incompletely dominant gene, as far as I can tell.

So going back to our theoretical horse, who at this point is a smokey grullo with splash, let's assume he also has sabino.  That makes him:

Ee aa CrC zz DD chch toto oo SW1sw Sb1sb lplp

It also makes him a flashy, flashy critter. lol Visually, the splash and sabino look pretty similar unless you look closely, but there's a decent chance you'd be staring at a grey horse with a black mane and tail, a dark stripe down his spine, some seriously high white stockings, an apron or bald face that wraps down onto the lip and chin (or even all the way around the face), and a jagged belly spot.  Maybe a random neck spot or two.

Next will be dominant white, which I love looking into.  I may have to split it up into multiple posts, though - there are over 20 different identified versions of it!  We'll see how much information I dig up.  :)

Classic paint

What I consider the classic paint genes are tobiano, frame (lethal white overo), and splash.

Now... the APHA would probably sort of disagree with me, because they include sabino (which I'll cover with the roaning patterns) and generally frames all colors as tobiano or overo (with subvariations of splashed overo vs frame overo vs sabino overo).  Or tovero, which... is not a thing at the genetic level; it's just tobiano plus an overo pattern.

White patterns will almost always have pink skin underneath them, which can make it fun to give a grey horse a bath sometimes.  :)  Sometimes they may have edges where the normal dark skin extends under the white, which produces a look that is apparently highly desirable in the model horse customizing craft community.  (Another random thing that I have knowledge of...)

Also of interest, if you've ever picked up a horse book by a British author (I plead the fifth on how many horse books I have, by the way) - the terms piebald and skewbald just refer to black-based pintos (piebald) and pintos with any other base color (skewbald).

And a tri-color pinto?  That's actually a bay, unless your horse has a chimeric mutation.  Chimeric mutations are when a horse had a twin while in the womb, and the two merged during development.  That's what gives you things like brindle horses (some of which are so neat to look at) and horses where part is black and part is chestnut.  This link has some cool examples.

So let's talk tobiano first.  Tobiano is dominant, so you only need one copy to see the pattern.  The edges of the white are smooth lines, not jagged - like drawing a curve vs. drawing steps.  The horse's head is generally dark with minimal markings (blaze, stripe, star); if they've got a flashy head, chances are they've got another pattern gene causing that.  In general, it's a vertical pattern - it crosses the back and tends to be very up and down along the horse's body.  I've seen it described as oval, but I have a hard time seeing that on most horses

These two are awesome examples of tobiano (from a local show).

White from the knees and hocks down is pretty commonly a tobiano thing, as is white crossing the back between the withers and tail.  Tails may also have white in them.  The chest and flank both tend to be dark, as well - sometimes the dark on the chest and neck is referred to as a shield shape, but I'm iffy on that description.

Better view of that red horse (Is he chestnut or something else? Not sure!) and his tobiano

It's notated in genetic testing as to (off) and TO (on).  Some people say that if there are dark spots in the white, that means the horse is homozygous tobiano (homozygous = both genes turned on), but that may or may not be true.

This is going to be a theme with the white patterns: they can hide. There's a theory - or at least there was - that there are either white enhancers or white suppressors (or both) that determine how much white a horse expresses when it has basically any pattern but the Appaloosa ones (which have their own rules on how they express white).  That means that how a given gene can show can vary wildly from horse to horse.

Tobiano can range from high white socks (usually with even, smooth edges) and a white tail, all the way up to just the head being dark and everything else white.  You can get dark horses who just have a single white spot that crosses their spine.  Googling "tobiano horse" shows a lot of cool examples, although quite a few of them are mixed with other patterns!

Minimal expression of tobiano at the local show

Frame is the nasty one, in my opinion.  Remember, it's got that alternative name of lethal white overo, and it has it for a reason.

Frame is a dominant gene, usually notated as o (off) and O (on), but the chance that you'll ever meet one with both copies turned on is very, very low.  All of these color and pattern genes are mutations of genes the horse as a species already had.  Most of them are pretty benign mutations - they don't really affect anything negatively.

Frame is different.  Frame actually affects the development of the colon when you've got two copies of the gene turned on.  And by 'affects' - it stops it. Foals who are OO are carried to term normally and are born white or near-white.  They typically have blue eyes.  And within a few hours of birth, they start to colic, because their intestines don't actually work, and they have to be put down.

And frame hides pretty effectively sometimes.

In its largest expression, you get a horse where - well, think of it like you're looking at a drawing of a horse.  All the edges are colored in, and the middle is white.

You know, kind of like this. (From a local show)

Or this guy.  (From a local show)

The pattern is generally termed horizontal - it goes along the length of the body, not up and down - and it only ever crosses the mid-line of the body if another pattern is involved.  The edges are jagged and uneven.  Tails stay dark, but the face may have bold white.  Frame can also cause blue eyes.

In lesser expressions, though... it puts points on socks, and that might be all you can see - or it might even just turn the horse's eyes blue, if the horse doesn't have white.  It likes to make other patterns jagged and sharp around the edges, and if the other pattern is big enough - like, say, a large tobiano pattern - those sharp edges might just be all you see of it.

What this comes down to is: test your horse if you're going to breed, if there's any chance mare and stallion might have pintos in their pedigrees and you don't know for a fact that their parents don't have frame.  Don't be the backyard breeder that doesn't test and then goes on FB or forums begging for sympathy for your sick foal.  Don't be the breeder that gets a white foal and puts it down because you assumed it's a double-frame because it's white; double creams can look white and other patterns can produce white foals with perfectly healthy intestines.  Just... don't.  The test is like $25 in the US plus postage to mail in some hair; if you're breeding horses with pinto patterns, you have no excuse.

*cough*  Sorry, had an opinion caught in my throat there.  Let's move on.

Splash (or splashed white) is kind of fun.  There are actually four documented versions of splash - SW1, SW2, SW3, SW4, and a theoretical SW5 (or more).  And off is just sw.  Like cream, it seems to be incompletely dominant; one copy turned on gives you white, and two copies turned on gives you more white.

Two copies gets complex, though, when you've got this many possible types.  Homozygous SW1 (two copies turned on) is fine, and not uncommon.  So far, they haven't found horses with two copies of SW2, SW3, or SW4, so the theory is that those foals may just be aborted in utero.  However, there are horses with test results showing two different versions of splash - say, SW1SW2 - and those are obviously walking around just fine.  (No SW2SW3 documented so far, though.)

As a general concept, highly expressed splash white looks like what would happen if you picked up a model horse and dipped it toes-first into a bucket of white paint.  The topline stays dark, but the face, body, and legs are white, and the tail may be too.  Lesser expressions aren't quite so dramatic.  High white socks/stockings and white belly spots are common.  So are bottom-heavy blazes - where the white on the nose is wider than the white on the forehead - and bald faces.  The edges of the pattern are crisp and even, and blue eyes (or partial blue eyes) are common.

Possible splash - look at that white face!

One side note - if the white reaches the ears, which can happen, there's a chance that the horse will be partially or completely deaf.  It's not true for all horses where the white reaches the ears, because it apparently depends on whether the white reaches the inner ear, but it does happen.

Splashed white 1 is far and away the most common of the four.  It's been found in everything from stock horses to Icelandics to Shetlands, and it's theorized to date back to before the development of most modern breeds.

Borrowing from Wikipedia again - pretty high white expression here.

Splashed white 2 traces from a single QH mare foaled in 1987, apparently, and there are rumors that it's related to the Gunner line of Paints as well.  It looks pretty similar to SW1.

Splashed white 3 is similarly a look-alike for SW1 and thought to be related to a small group of horses; at the time the paper that identified it came out, there were only two examples known.

Splashed white 4 is even more rare!  It showed up in a single (and sterile) Franches-Montagne horse and is sometimes called macchiato.  Equine Tapestry has a great post about him here.

Splashed white 5 and up are mostly theoretical at this point, as far as I can tell - they're believed to exist, but there don't seem to be tests or completed studies yet.  There's some talk about an "Appaloosa splash," but the paper it points to doesn't seem to talk about that at all (as best as I can tell).  There's also a family of Australian stock horses - the Bald Eagle line - that look splash, but thus far haven't actually tested as splash.  (You can see those guys here.)  There are also splash-like (and sabino-like, which we'll talk about in the next post) patterns in Gypsys and Clydesdales that haven't been identified genetically yet.

The Splashed White Project page at Equine Tapestry is actually an awesome place to see some of the variants of splash - she's got them grouped by gene combinations, so you can look at all SW1SW1 horses, or all SW1 horses with frame.

Some combinations can be pretty flashy!  It's not always easy to tell when you're seeing a combination of patterns, but often the major patterns are easy to spot - up and down shapes from tobiano, jagged white from frame, white faces from splash.

At least tobiano and splash on this guy (at a local show)

Tobiano and frame or sabino (see the ragged edges?), same local show

Other side of the same horse

Tobiano, frame, and maybe splash (looking at his face) at the same local show

Either splash (see the belly spot?) and frame, judging by that neck white and the points on the leg white - or sabino, which we'll talk about next. (At the local show)

Now, let's go back to our theoretical horse from yesterday.  Let's say he has splash.  Now his test results would look something like this:

Ee aa CrC zz DD chch toto oo SW1sw lplp

He gets the toto because he doesn't have tobiano, the oo because he doesn't have frame, and the SW1sw because he's got one copy of splashed white 1.

Next post, I'll talk about the roaning patterns: roan, rabicano, and sabino.

Spring is definitely going to be interesting!

So I walk up to Justice today, and I'm greeted with this:

This was two weeks ago:

Baby boy, you're kidding me.

AND your muzzle now looks mottled.

And as for your tail... L to R: normal view, pulling back the side hair, and braiding it.

You're gonna shed out mostly white, aren't you.

And he's now reached his first real baby phase, I think.  Turning right is currently not a thing he thinks he knows how to do.  Instead, he backs up three or four steps, then reluctantly turns as little as possible to go right.  It's all in slow motion, which makes it hilarious, and I don't really feel like I need to scold him for it yet - he turns eventually, and he does respond promptly.  Just... not quite in the right way.

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.