Newsgroups: rec.equestrian



                      THE GENETICS OF COLOR

Thanks to: tracy@scoraz.resp-sci.arizona.edu (Tracy Scheinkman)

	Horse Color by D. Phillip Sponenberg and Bonnie V. Beaver
is an excellent book on horse coat color genetics.

	When my mare was pregnant last year I became very interested
in color genetics in horses I wanted to know the probabilities for the
color of the foal.  My mare is a grey, the sire is a bay (our baby is
a beautiful bay filly rapidly going grey).  This is a basic version of
what I found out as I am a biology student.  I may use some very
technical terms but I will try and make them understandable.

	First, color inheritance in horses is NOT governed by a single
gene.  Hair color of horses like hair color of humans and other
mammals is governed by many genes interacting with each other.

	To a certain extent it can be thought of as a series of
transparent overlays with a figure of a horse underneath, what color
the horse is depends on which overlay is uppermost and how much of the
underlying colors it allows to show through.  For example in the case
of a horse which has both a gene for roan R and a gene for grey G,
both of which are dominant genes, you will not be able to tell that
the horse has a roan gene because the greying covers it up.  The only
hint you would have would be when the foal is just born if their coat
is about half white hairs mixed evenly with the backround color,
except at the head where roans do not have as many white hairs as
greys, then you would know that the foal carried roan coloring but
shortly thereafter the foal's coat would begin to grey out as the grey
gene is a progressive whitener of the coat.  Thus as an adult the
horse could conceivably carry a roan gene and yet look perfectly
white.

	Now on to the next lesson.  Genes always come in pairs.
Geneticists label them with a capital letter if the gene is dominant
or a small letter if recessive thus G represents grey color and is
dominant g represents non- grey and is recessive.  In order to see a
recessive color both genes in a pair must be recessive thus a bay
horse would have gg at the grey gene location (called a locus) and a
grey horse would either be GG or Gg.  Got it?

	Next, not all books use the same lettering system for
different genes a gene called A in one book might be B in another.
Just look for consistency within the book or article itself.  The book
I will be referring to is called Horse Color and was written by D.
Phillip Sponenberg,Phd.,DVM and Bonnie V. Beaver.  Sponenberg is a
researcher with a university in Virginia, I believe, and is still
doing research into horse color.  This is a wonderfully complete book
which includes over a hundred color photographs of the various coat
colors and patterns they discuss.  The appaloosa information which is
in the book is incorrect and Sponenberg has recently published new
information on appaloosa inheritance which I have included here (see
Equus, April 1990 issue).

	Horses have available two different color pigments eumelanin
which is responsible for black and chocolate brown horses and the
black in a bay's mane and tail, and phaeomelanin which is responsible
for the red or yellow color of sorrels, chestnuts, palominos, and the
red body on clear bays.  Now we're ready for the genes themselves.

	A	a dominant gene is responsible for bay horses by restricting
		eumelanin to the points or the mane, tail, and legs of the
		horse, the rest of the horse has red phaeomelanin pigment
		(note the exception: dark mahogany bays and seal browns
		have other genetic elements at work, mahogany bays have an
		additional gene allowing some eumelanin, seal browns are
		actually genetically black with another gene P causing 
		light areas on muzzle and flanks)

	a	the recessive gene is responsible for black and uniform
		chocolate brown horses, a common color for Morgans and
		some Quarter Horses, this gene allows eumelanin over the
		whole horse uniformly

	B	a dominant gene for the black variety of eumelanin

	b	a recessive gene for the brown variety of eumelanin, the
		difference apparently is in the microscopic arrangement
		of pigment molecules, these horses also tend to have
		amber or light brown eyes and pinkish brown skin, in order
		to have a uniform chocolate brown horse then the horse must
		be aabb, if it is A-bb then it is a bay with brown points
		instead of black (red body, brown mane tail and legs)

	C	this gene means that the horse's color is fully expressed,
	 	non-dilute

	 cr
	c  	this recessive gene is the cremello gene it dilutes phaeo-
		melanin markedly, eumelanin a little, it is responsible
		for blue-eyed light cream or white horses that some
		call Albinos (true name cremello if chestnut is diluted,
		perlino if bay is diluted), however there is no true Albino 
		gene for horses, this gene is also incompletely recessive so 
		when big C and little c-cr are present in one gene pair a horse
		that would otherwise have been chestnut or bay would be
		instead palomino or buckskin respectively.  Fascinating, huh!

	D	is responsible for all dun horses except claybank duns
		which are mostly c-cr horses, duns have dorsal stripes, some
		also have leg striping

	d	non-dun

	E	this dominant gene allows eumelanin at the points meaning
		it allows bay and black this allowance of black color
		becomes important because of the next gene

	e	this recessive gene causes phaeomelanin red or yellow
		over the whole body in other words chestnut, sorrel, or 
		palomino, this gene is said to be epistatic to the A locus 
		this means that if two e genes are present they cover up
		the effects of A or a, think of it as opaque plastic overlays
		the horse might have been black, bay, or brown according
		to its other genes but because of ee it's red (note: sorrel
		and chestnut both generally refer to the same color, red,
		however different breed associations refer to the lighter
		phases of the color differently than the darker phases of
		the color, to further complicate things different breed
		associations do not agree as to what term shall cover what
		shade of color)

	 d
	E 	the proof for this gene is incomplete, this is a dominant
		gene at the E locus that causes the color called jet black
		which is a non-sun-fading black color mostly seen on
		Clydesdales and a very few other large breeds it is not
		present for example in Arabians whose black color when
		present comes solely from the normal recessive mechanism

	F	normal red mane and tail on ee, chestnut or sorrel horses

	f	flaxen mane and tail on chestnut or sorrel horses

	G	grey, this dominant gene is like a transparent plastic
		overlay, when the foal is born whatever color it would
		have been without the G shows through, thus it is black,
		or chestnut or bay or whatever, then as it grows older
		it progressively whitens as each new coat gets more and
		more white hairs mixed into it

	g	non-grey

	P	pangare (pronounced pan-gar-ray), this causes light areas
		on muzzle, over eyes, on flanks, stomach, it causes
		black to become seal brown and chestnut with flaxen mane
		to become blond	sorrel

	p	non-pangare

	Sty	smutty, causes some black to become mixed into body coat
		clear sorrel becomes chestnut or liver chestnut clear bay
		becomes mahogany bay palomino becomes smutty palomino

	sty	recessive causes clear pure color, a clear pure red is 
		often called sorrel among Thoroughbreds and Quarter Horses

	Z	silver dapple, causes eumelanin to be diluted to flaxen,
		this gene is really only a factor for breeds such as
		Shetlands, Icelandics, Dutch Warmbloods and Norwegian Fjords,
		Norwegian Fjords may have a combination of dun and silver
		dapple genes

	R	roan, causes white hairs to be mixed with base coat color,
		this color is non-progressive though it does change a little
		with the seasons, also this gene is thought to be a dominant
		lethal meaning that RR horses die during developement, most
		roans are Rr and throw solid colored foals as well as roans,
		Dutch and Brabant draft horses may be an exception to this
		rule and if so roans in those breeds are probably due to
		some other mechanism

	r	non-roan

	T	tobiano paint spotting, the amount of white is governed by
		independent modifiers and can be selected for, thus a
		tobiano with a lot of white will tend to have foals with
		a lot of white

	t	non-tobiano

	O	non-overo

	o	overo paint spotting, overos that are mostly or all white
		often die within a few days of birth because of a malfunction
		of the colon, the amount of white caused by this recessive
		gene is governed by an unknown mechanism possibly womb
		temperature maybe independent genes but cannot be selected
		for, overos often throw solid or nearly solid foals

	Sb	sabino paint spotting, often confused with overo, the minimum
		expression seems to be high white stockings and extreme
		facial white, common among Clydesdales where the color is
		sometimes erroneously called roan, many horses exhibit the
		Medicine Hat pattern popular among some breeds such as the
		North American Spanish, white foals develope normally
		in contrast with overos

	sb	non-sabino

	Note: the term tovero refers to a horse which exhibits a combination
		of overo and tobiano patterning, such horses would be 
		genetically T-oo, a horse that is genetically T-ooSb is 
		theoretically possible

	W	dominant white, this is the gene we see in the American
		Albino horses, it is not a true albino gene, the skin is
		pink, the eyes of such horses are usually brown, also this 
		is a lethal gene meaning that all Dominant White horses are 
		Ww, the WW form is unknown there are no exceptions

	w	non-white

	Apl	non-appaloosa, to be a non-appaloosa the horse must be
		Apl Apl

	apl	this is another incompletely recessive gene, apl apl horses
		are the few spot appaloosas that produce 100% appaloosa
		babies no matter who they are mated to, Apl apl horses are
		the brightly patterned appaloosas we are most familiar with,
		other modifier genes causing the different patterns leopard,
		blanket, varnish roan, etc., there may be other appaloosa 
		mechanisms that are unknown currently (note: the grey gene
		has the same affect on appaloosa pattern spots and splashes
		that it has on solid colored horses and eventually such
		appaloosas that carry the G grey gene will become completely
		white just as solid grey horses do, in those cases the skin 
		under the white hairs is often visible and is pink in the 
		blanket areas and dark where the spots or solid areas were, 
		thus an all white horse with pink skin and a few oval spots of
		dark skin may actually be a few spot appaloosa that has turned 
		grey)

	Now how it works, let's take the case of a black horse which is one
of the most difficult colors to achieve in most breeds.  Remember that
chestnut ee covers up black aa and bay A-.  So a chestnut horse with a black
ancestor is bred to a bay horse with a black ancestor, the chestnut's gene
pattern looks something like a?ee the bay's gene pattern looks something
like AaE?, now there are 16 different combinations possible of which 4 are
definitely bay, 4 are bay or chestnut depending on what genes the ? are,
4 are chestnut or black, 2 are bay or black, and only 2 are definitely black.
If we make the first ?=A and the second ?=e then, the possible offspring
are 8 chestnuts, 6 bays, and 2 blacks in other words a ratio of 4:3:1.   When
you add more color genes it becomes more complicated.

	There was someone who had a question about an overo and a tobiano
being mated together, in such a case one would need to know the colors of
their parents in order to find out whether the tobiano possibly harbored an
overo gene, if not then a paint offspring would likely be tobiano, a solid 
colored offspring is also a possibility, either of which when bred to an 
overo could produce overo foals in the next generation.  I don't remember 
the colors but they add more complication to the picture.

	As to the grey question, grey covers up the base color, let us say
that color is bay, well bay can hide a black gene or a chestnut gene, so
depending on what the grey is bred to you could have a chestnut, a bay, a
black, or another grey, or numerous other colors.  Remember to look at
your horse's breed and parentage, certain breeds don't have some color genes
available to them.  For example Arabians don't have Z silver dapple or E-d
jet black, and b chocolate brown is a tremendous rarity, so those genes
are unnecessary to consider.  My mare's line has had nothing but greys, bays,
and chestnuts for many generations, black was known eight or ten generations
back but hasn't shown up since then so I won't need to bother checking for
other colors such as overo genes or cremello genes when I breed her to another
of her line.  Since I am interested in black I would want to see if the sire
had a line that included black genes.  One more thing, the likelihood of a
recessive gene showing up in subsequent generations decreases with each new
generation that does not show it, but as in the case of black coloring, it
never completely goes away.


++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

>I have a mare (9yrs.) that was born a bright chestnut with just a small
>white blanket (no spots) over her hips.  When she began to shed her baby
>coat, there was a lot of white mixed in (a greying gene - G), but also,
>small copper spots appeared all over her body (today she looks nearly
>like a leopard with varnish marks).  I'm assuming that - using a
>transparency effect - that she had not only a greying gene, but also a
>gene for leopard type spots over her body and that the spots really
>didn't appear, but were actually there the entire time, but weren't
>visible in the original chestnut base color.  When the greyign kicked
>in, replacing the base color, the spots then became visible.  Since the
>greying didn't affect the spots - they must be governed by something
>the greying cannot effect.  This mare's mother is a true red roan, but
>with a grey gene - she is still pretty roan, but lighter than at birth
>(she's 22 now).  The sire of my mare is a leopard with strong leopard
>breeding (Prince Plaudit).

Well, the first thing you know (besides the fact that your mare is from
racing lines, I believe Plaudit was a race horse of some merit) is that
your mare has two ee genes otherwise she wouldn't have been born chestnut.
She also carries an Appaloosa gene which allows the pattern to show through,
but since she's greying out that pattern will eventually dissappear.  I
suspect she also has an R roaning gene because of how the spots stood out
from the backround for a while.  She has at least two pattern genes, the
appy pattern genes can be carried by solid horses but won't be expressed
unless the horse is either Apl apl or a few spot appaloosa.  There are
numerous pattern genes, at least eight patterns are suspected, your mare
carries a blanket pattern gene and a leopard spot gene.  Also she has
two flaxen genes ff indicated by the flaxen mane.  So far we
have your mare as: ee ff Gg Rr Apl apl and since I am not sure whether the
pattern genes are dominant or recessive we'll give her at least one
blanket gene and one leopard gene.  (What a neat horse, you should write
to Dr. Sponenberg and tell him about her.)

>Now, I bred this mare last year.  I bred her to a grey QH who has strong
>grey, black and what I call near black (even darker than a seal brown -
>they look black except upon very close examination of the muzzle and
>when the sunlight hits them just right) breeding.  What I got, basically

	Note: dark almost black is still considered seal brown, it is
	genetically black with the pangare gene causing the light areas
	on muzzle and flank

>surprized me.  I got a solid chestnut colt with a chestnut, mane and
>tail with some blond highlights (mom has a very blond mane and tail).  I
>did expect more color at birth.  I an convinced that this colt will grey
>out.  He does seem to be changing much slower than mom did though.  As

	I agree he will grey out, the grey gene causes greying at faster
or slower rates based on other genes that can be selected for, but in
this case I think that this is another indication that mom had roaning
helping her to look grey faster.

>he's losing his baby coat (he's 4 months now) there is some roaning
>around his blaze and some white hairs around the base of his mane (his
>mom was already making dramtic changes as she shed her baby coat and was
>the color she is now by the time she was 2 yrs.)  .  I am sure he will
>gradually turn grey; whether he has any other body spots like mom, I'll

	The description you have of him already having some white hairs
on his face confirms the grey gene, generally greys will start greying
at the face which will always be a little whiter than the rest of the
body, whereas roaning generally is not as heavy or is non-existent on
the face.

>have to wait until he greys more.  Mom is rebred to same grey stud for
>'92 - so we'll see what we get.
>Any thoughts on how this colt might turn or what I'll get next year?
>Also, this colt thus far has some future stallion potential.  I'm
>curious as to what his color producing potential is and whether he's
>produce any strong color other than greying.  App/QH crosses are a big
>market and a good stallion will have to throw color even out of QH
>mares.  What do you think?
>Kitty Cummings

	From your description the stallion is G- (-means we don't what
gene is paired with this one) what gene is paired with this can make
a difference to you as a GG horse throws nothing but greys, not very
useful for making colorful appaloosas.  If the stallion is Gg on the
other hand then there is a 1 in 4 chance that a mating between him
and your mare won't be grey, 3 in 4 that they will be grey.  This
stallion definitely harbors an e chestnut gene, otherwise your colt
wouldn't be chestnut.  Since mom is Apl apl then the chances are the
reason your colt hasn't shown spots or pattern is that he did not
inherit one of the base apl appaloosa spotting genes from her, thus
any pattern genes he has would remain hidden only to show up when he
is mated to an Appaloosa mare, especially a few spot, but under those
circumstances he could produce either a blanket or a leopard pattern
depending upon what he inherited from mom, both patterns in one horse
are possible.  I believe from what you have said that he has one grey
gene, not two, as horses who carry two GG genes tend to grey out very
fast.  If that is the case then there is a 50% chance that he can
produce a non-grey if he is bred to a non-grey.  He also carries the
potential for a black, however that won't happen if he is bred to 
a chestnut as chestnut covers up black and bay.  So far your colt is:
a- ee Gg rr Apl Apl (meaning non-Appy) and probably carries one blanket
and/or one leopard gene (he definitely does if these are recessive genes). 
He may or may not carry the pangare gene which the stallion may carry, we
don't know nor will we unless your colt produces a seal brown.

	If I were you I would breed this colt to nothing but Appy's with
color who are non-grey that would up his chances of producing color.  
Also if you want black don't breed to a chestnut or chestnut Appy because
he will definitely produce chestnut then (of course if you like chesnut
that's great).  P.S. he may also be able to produce bay when bred to
a non-chestnut, black is tough to get.  If he spots out later (please
excuse my ignorance in this area and enlighten me if you have time) then he
will be shown to carry one apl gene and can pass that along 50% of the
time to both spotted and non-spotted horses.

	The Sponenberg book is the only really good book on horse color
genetics that I've ever found, it was published in 1971 and I borrowed a
copy from the University of Arizona library and xeroxed almost half the
book.  It is called "Horse Color" by D. Phillip Sponenberg and Bonnie V.
Beaver, I believe it was published by the Texas A & M University Press.
I found a good section on Appaloosa color in another book that was being
used as a text for a horse management class at Pima College a few years
ago but I do not recall the author or name of the book (sorry).  Good
Luck to you and your horses.  By the way your mare has a good chance
of producing a non-greying appaloosa if bred to a non-grey stallion,
50% chance non-grey, 25% chance non-grey Appaloosa, but as you point
out color is not everything, conformation is very important and should
override color choices in many cases.

				Tracy and everybody
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Tracy,

Thanks for the response - I had once taken a genetics course in college,
but had kind of gotten away from it.  Now, though, this discussion on
color has really peaked my interest again.  Though appy genteics are
complicated - I think it would be neat to not only breed for
conformation and working ability (as these two are certainly more
important than color), but to also selectively breed for and predeict
color.

I'm still assuming that the greying gene doesn't always affect patterns
as my mare (an I've seen others) definately greyed, but the leopard spot
pattern left behind has not changed since she was 2 yrs.  In other
words, she did all her chameleon stuff before she was two and has not
turned another odd hair since (she's now 9, so I don't anticiapate any
further change).  So with my colt, I'll have to wait for the greying to
take palce to se if there is another underlying coat pattern like mom's.

>From what you said, I think I'll probably get a foal next year that is
very similar to this years.

In '92, I will breed this mare to a dun leopard - I think when I get the
book, I'll have to spend some time predicting what I'll get.  Care to
take a stab at it?

I would like, in my breeding program to produce duns, buckskins, red
duns, grullas, palominos and blacks (I know this will be tough) - I'd
like to get away from chestnuts, bays, etc (too common).  I realize I've
got my work cut out for me, as obviously I've got breeding stock that
already carry alot of chestnut and greying gene and as these horses are
good stock pedigree, conformation and working ability -wise, I'm not
going to run out and scrap them.

Can you give me some idea as to producing palominos and what crosses are
most sure to give palomino?  I've bred buckskins, red duns and grullas
- but I've never produced a palomino.

Thanks for yout help Tracy - I find this whole subject fascinating!

Kitty Cummings
Kit-Mar Appaloosas
Ritter Hof German Shepherds

+++++++++++++++++++++++++++++++++++++++++++++++++++++
Kitty writes:
>In '92, I will breed this mare to a dun leopard - I think when I get the
>book, I'll have to spend some time predicting what I'll get.  Care to
>take a stab at it?

	Ok, I'll give it a try from memory as I don't have your original
post in front of me.  Your mare has a 50% chance of producing a grey,
because she carries one grey gene, sorry you can't get away from that.
The remaining 50% can be divided as follows: 12 1/2% chance of a few
spot Appy, 25% chance of a brightly patterned (very probably leopard)
Appy) 12 1/2% chance of a solid colored horse.  The dun gene is dominant
so if the sire is carrying only one dun D gene then he has a 50% chance
of producing dunning (which if the horse is also grey will grey out,
if the horse does not grey should be quite striking), if he is carrying
two dun genes DD then all versions whether they grey or not will be
initially dun.  You don't say whether he is a red dun leopard or some
other shade so I can't speculate on that.  Also since your mare 
is also a roan Rr then 50% of time roaning will affect the 
colors.  So a wierd but not impossible horse could be a red dun roan
leopard appy which has a 50% chance of greying or not.  P.S. a blanket
pattern is also possible since your mare carries that as well.  At
the opposite end a solid-colored horse that greys out is also possible.

>I would like, in my breeding program to produce duns, buckskins, red
>duns, grullas, palominos and blacks (I know this will be tough) - I'd
>like to get away from chestnuts, bays, etc (too common).  I realize I've
>got my work cut out for me, as obviously I've got breeding stock that
>already carry alot of chestnut and greying gene and as these horses are
>good stock pedigree, conformation and working ability -wise, I'm not
>going to run out and scrap them.

>Can you give me some idea as to producing palominos and what crosses are
>most sure to give palomino?  I've bred buckskins, red duns and grullas
>but I've never produced a palomino.

	Palomino and buckskin (true buckskin as opposed to dun buckskins)
are caused by the incompletely recessive c-cr gene.  This is the gene
that causes cremellos and perlinos.  When both of the genes at this locus
are CC then the horse is an ordinary non-creme, non-palomino.  When both
genes are c-cr c-cr then the horse if bay genetically will actually be
perlino (creme to white body color, reddish points, blue eyes) and if
chestnut genetically it will be cremello (creme to white body color, 
off-white points, blue eyes).  If one C and one c-cr gene are present
then the horse will look buckskin (yellow body color, black points, 
no stripe) if chestnut genetically the horse will look palomino (yellow 
body color, flaxen to white mane and tail).  Your best chance therefore
of producing palomino would be to breed a chestnut mare to a cremello
stallion or vice versa, this would give 100% palomino coloring.

>Thanks for yout help Tracy - I find this whole subject fascinating!

	So do I.  Remember the more colors you add in the more 
complicated things get.  Also, if your mare is definitely greying
then the spots will eventually grey out too, however the skin under
them will stay dark and will probably be visible under the white
hair coat.  I have seen a photo of a Lippizzaner/Appy cross that
looked exactly like that.

				Tracy and everybody 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++


>can enlighten me with.. I am buying a grey (3 mos filly) out of a chestnut
>appy, and a red roan appy mare. Both parents have a leopard spotted sire,
>and the grandsire on the dams side was also a leopard. 

	If both the parents were non-greys gg this filly cannot possibly be
a grey.  The rule is that only a grey G- can produce a grey.  This is 
absolute.  If she is indeed out of the parents mmentioned then, either a)
she is not really a grey but a roan, check her head and compare to the 
body greys generally have more white on the head or at least the same, roans
usually have less white on the head than the rest of them, or b) one of
her parents probably the red roan appy mare is really a grey but not changing
color very fast, or c) this filly is not sired by that leopard spotted sire,
or d) he is the grey, but again not greying out very fast, check his spots
for white hairs mixed in.

>She is beginning to mottle out mouth area, has some scerla around eyes, and 
>she does have some spots. I was hopeing she would roan out either chestnut
>or sorrel, but she may stay grey, and just white out. 

	If she is actually a roan then her color will change seasonally but
not much when compared year to year.  She is just now getting her adult coat
and that may be somewhat different from the baby coat, so that may be making
you think she is grey, check for white hairs mixed into the base coat on the
face.

>Anyway,
>do you think this filly would throw nice appy foals if bred to a few spot
>leopard stud? From what I have been reading this should work, but no guarantees.
	If she is a roan with spots she will definitely throw appys, including
a fifty percent chance for a few spot appy.  If she is a grey then you probably
have only a fifty percent chance for a true non-greying appy and a fifty
percent chance for another grey.

>I also have a chance to buy a leaopard colt, have not seen him yet, out of a 
>leopard stud, and solid bay mare. Do you think he would throw color or forget
>him. His sires pedigree is unknown , dams side is pretty much solids, chestnuts,
>bays, roans.. Any help would be appreciated.

	If the leopard colt is brightly patterned and non-greying then he will
throw color about 50 % of the time when bred to non-appys and 75% of the time
when bred to other brightly colored appys.  Keep in mmind conformation is as
important as color.  If he is a few spot Appaloosa then he will throw color
100% of the time, although this is unlikely unless his dam is also an appy.

					Tracy and everybody
++++++++++++++++++++++++++++++++++++

Janet Ashnault writes:

>It sounds like there are some color experts out there - perhaps you could
>assure me that my horse is indeed a dun. 

>Here's basically what he looks like. The front half of his body, believe
>it or not, can best be described as the colors of a Butterfinger candy bar.
>Looking closely, you can see the hairs are orange and brown. He fades nicely
>to just the chocolate brown on the back half of his body. His legs have
>some dark brown highlights down low except for the back left which fades
>into a golden dun color!

>His mane has an equal distribution of black, white and flaxen
>hair and at a quick glance - you might call it gray. His tail seems to have
>every color hair in the rainbow, but is basically dark orangey brown with
>a beautiful flaxen highlight.

>He has a faint, faint dorsal stripe. 
>I don't know if this will help any, but this horse has brown eyes with
>huge gold flecks in them!

>To top it off - his winter coat comes in as such a light dun color - it's
>hard to tell him apart from a gray pasture buddy when they're way out into
>the field. 

>I've gotten many compliments on his color (and eyes!) and mostly I just
>say he's a dun. Someone once suggested perhaps chocolate palomino?? 
>All I know is that with all his color changes during the year, it's sorta
>like having several different horses -- all with the same great personality!

Hi, Janet, yes it sounds very much like your horse is some variety of dun,
there are several interesting possibilities as to his genetic backround from
your description.  He could be a chocolate brown aa bb with a D- dun gene
causing him to lighten on the body to that golden color you mention, and
I suspect this is the case because of the (I assume) light? brown eyes with
the gold flecks in them.  This color for eyes seems to go hand in hand with
the bb brown eumelanin color, as does pinkish grey skin, instead of dark
grey skin (you might check his skin color for me).  The bb gene is the same
one that causes pink-skinned palominos by the way.  If this horse is indeed
aa bb D- this color is sometimes called muddy dun, not very accurate
considering how handsome he sounds.  The white in his mane in this case
might come from Z the silver dapple gene or it might be something wierd
and uncharacterized.  
	The second possibility is that he is what is sometimes termed a
copper dun, which is a liver chestnut with the dunning gene on top of it.
In this case he would be D- ee Sty- and probably ff flaxen gene.  Without
knowing anything about his parents or seeing a good color photo of him
it seems impossible to tell for certain.  He certainly sounds quite lovely.

				Tracy and Bruce (beautiful man) and
				Cachet (6 year old grey Arabian mare)
				and Mithril (1 year old grey Arabian 
				filly) and The Cats
 
++++++++++++++++++++++++++++++++++++++++++++++++++


>I've always heard that a palomino bred to a chestnut will produce palomino
>50 % of the time, perhaps Tracy can clarify...

	You're absolutely correct.  Palomino is by definition Cc-cr ee and
chestnut is CC ee, so the 1/2 of the offspring will inherit the palomino
c-cr gene plus a C gene from the chestnut therefore they would be palomino,
the other 1/2 of the offspring would be CC ee chestnut colored.  The only
way to achieve 100% palomino color is to mate a cremello c-cr c-cr ee horse
with a chestnut CC ee horse.

>Also, Tracy, I have a red chestnut mare.  I am breeding her next year to
>a chestnut stallion so I will certainly get a chestnut baby.  If I breed
>her to a black/bay (Arabs that are black with brown muzzle are called 
>black/bays), what kinds of color can I expect.   I am fairly sure the
>stallion's sire or dam was a solid black.  Oh, yes, he is a purebred Arab...

	The black/bay color is also known as seal brown, dark brown, etc.
it appears to be caused by the action of the P pangare gene on aa black
horses.  So this stallion is probably aa E- Pp.  We don't know whether he
harbors an e chestnut gene, or whether your chestnut mare ee harbors a
a black or A bay gene.  So your most likely possibilities are:  black
(difficult, but possible), black/bay, chestnut possibly even liver
chestnut depending on whether the stallion has an Sty gene, or normal bay.
I can't give you percentages because it depends on the genes we don't 
know about.

				Tracy
++++++++++++++++++++++++++++++++++++++++++++++++
Jodie Gilmore writes:

>My mare Mira is coal black with white markings in the winter, or in non-sunny
>areas of the country. When the sun shines on her, and when she sheds out, she
>has a black butt, and belly and legs, but her back and neck and shoulders are
>a dark bucskin color. Also, she gets "tiger stripes" on her ears, face, and
>sometimes on her shoulders. She has SOME white hairs on her barrel, but they
>don't seem to be multiplying at all. She also has an isolated black spot 
>on the back of one of her white pasterns.

>So is she just a boring "black/bay", despite the tiger stripes? (I've
>never seen another horse with stripes on its ears.) Or would you
>call her a black/buckskin? Or maybe a black brindle? 

	Hmm, some black horses, those who are aa blacks as opposed to E-d
jet blacks, get sunburned (i.e. they get fried) in the summer time and 
their black hair fades on the most sun-exposed areas to a reddish brown
color.  So this could be what is happening with her.  The zebra stripes
on her ears and shoulders are probably due to rubbing.  She could be 
black/bay but I don't think so as you do not mention brown or tan areas
on her flanks or muzzle.  D dunning or P pangare genes seems to cause the
color to be lighter in the winter than the summer so again it seems she
is a black that gets sunburned.

				Tracy and everybody
++++++++++++++++++++++++++++++++++++++++++++++++++


>Tracy:
>On the filly out of two appy parents, the lady said she thinks she may
>be a blue roan, since she has not been body clipped yet, could prove
>interesting. Her granddam on the sires side is believed to be grey, as this
>color appears every so often in the foals. The filly is out of these two
>appy parents, I have seen her nurse etc, and she only has the one stud.

	Grey can only come in direct line of descent from parent to 
offspring because it is a dominant gene G, it does not skip generations.
Therefore if it shows up in the sire's offspring, either he is a grey
who is being mistaken for a roan or the mares he has been bred to are
greys.  Roan R is also a dominant gene but here I think that there is
a lot of confusion as to which horses are greys and which are roans.
I suspect both that roans are being mistaken for grey and that greys
are being mistaken for roans.  Again roaning is not progressive, it 
changes only a little seasonally, meaning that the horse may be darker
in the summer and lighter in the winter but the next summer will be dark
again.  By contrast greys lighten progressively with each new coat being
shed out, some greys lighten very fast and are obvious, others take quite
a long time to grey out but even they have more white hairs in their coats
with each shedding, and they nearly always have more white on their faces
than roans who have comparatively little white on the face vs. the body.

>This will be good if she does throw appys.. That's what I was counting on, 
>now onto the stallion. I did some research on him last night. His sire was a
>spotted leopard, his dam pedigree says she was a grey (ugh), but when talking
>to the owner, she seems to think the dam eventually roaned out, which this
>stallion is just starting to spot out at 2 years of age. So I know this

	This is very confusing, roans generally are born that way, if the 
horse keeps adding additional white hairs to the coat it should actually
be a grey.  Perhaps someone more familiar with Appys can help here.  But
from the information I have and the description of the dam, I think she was 
a grey.  If the stallion is just starting to get white hairs in his coat then 
again from the info I have he is a grey.
	Of course if this line greys very slowly it may not matter, you
may only see totally white individuals only at very advanced age.  But I
think it is important to know which genes you are dealing with here.

>does happen. Of course when you register a foal and they are solid colored
>at birth, the papers state solid color, in the Miniatures, they don't make
>permanent till 5 years of age, and many people don't bother to change color
>on their papers till then. So this can be very detrimental when trying to 
>determine color of parents prior to 5 years old.

	This is very interesting and I think wise of this registry as so many
horses are of uncertain color that it takes a while to tell what color they
will be.  With Arabians there are a few hints (Arab foals should be registered
before they are 6 months old or it costs much more, although color changes
are possible at any time applications must be accompanied by photos) which
can indicate some things about color:  1st no horse can be a grey unless
one parent is grey, 2nd chestnuts and bays are sometimes of uncertain color
at birth look to new hair coming in on the muzzle and around the eyes to get
an idea of the adult coat, 3rd grey hairs are often first seen above the eyes
or on the eyelids when the horse is a few days old, 4th a horse that is born
black almost always changes color usually to grey, 5th a horse that will be
black is usually born a mousy color and sheds out to black.  There are a few
more.  My filly was born a beautiful blood bay color.  We only knew she would
be grey because we saw a few microscopic white hairs on her eyelids the next
day.  Even after she started getting grey in her coat her bright bay color
was so overwhelming that even at 8 months old I had people look at her and
say "Are you sure she's turning grey?"  Now at 16 months her mane has lots
of silver hair and they don't ask that question any more.

>Guess this studs chances of throwing all appys are not greatly reduced if 
>his dam was indeed a grey.. His conformation is excellent, I would not have
>considered him otherwise, and he has a super temperament, easy to handle.
>What are your thoughts now, think I should try him, even with my solid colored
>mares? He really is nice, and hate to miss the chance of getting him, and then
>later find out he does throw all appys..
>Thanks again, wait to hear your suggestion on this.
>Kathy.

	I'm big on conformation and temperment, but if you are looking for
all Appys then perhaps you should look a little farther.  However, many
Appys that eventually turn grey have spots or varnish roaning as well and
if they don't turn grey fast will look Appy for quite a while.  Also
Appys that do turn grey often can be seen as Appys since the dark pigmented
spots stand out next to the pink skin, this can be seen under a white hair
coat (not very pretty, but still Appy).  Again conformation and temperment
should weigh very heavily in your decision but you know what you are going
for and if it's color then that may make a difference.

				Tracy and everybody
+++++++++++++++++++++++++++++++++++++


This is for Melanie and Quest:

	In answer to your question about breeding Appy/Warmblood cross
for color.  Yes breeding a few spot Appaloosa to a warmblood would pretty
much guarantee a bright Appy type coat pattern.  An interesting note,
the Appaloosa color pattern used to be a favored one for harness horses,
especially warmbloods in Europe, Dalmation dogs were bred to match the
Appys.  Also I have seen a photograph of a Lippizaner/Appy cross who
was 1989 USDF Horse of the Year at Grand Prix.  Wonderful mover, noted
as having the best piaffe and passage of any horse the judges who 
judged him had seen, but he was kind of ugly, with a big Lippizaner head
and pink skin with a few dark skin spots under his white coat.  You see
he was a grey.  So when you breed your Appy/Warmblood cross choose a
non-grey for the Warmblood part, that way the pattern will not grey out.

				Tracy
++++++++++++++++++++++++++++++++++++++++++++++++++++

>b) is Bay also a dominant gene such that two bay horses should
>always produce bay?  
	Bay is a dominant gene, however the only colors that always 
breed true are the recessives such as ee chestnut, if you breed two 
chestnuts together you will get chestnut, no exceptions.  Dominant 
genes such as A bay can hide or cover up the presence of recessive 
genes such as a black, or e chestnut.  Other dominant genes located 
at different locuses can cover up bay, for example G grey.  My yearling 
filly was born bay and is turning grey, by the time she is six or seven 
she will be almost white with very little to show for the bay color she 
carries.

++++++++++++++++++++++++++++++++++++++++++++++++++++

Linda Newell writes:

>>>b) is Bay also a dominant gene such that two bay horses should
>>>always produce bay?  
>>	Bay is a dominant gene, however the only colors that always 
>>breed true are the recessives such as ee chestnut, if you breed two 
>>chestnuts together you will get chestnut, no exceptions.  Dominant 
>>genes such as A bay can hide or cover up the presence of recessive 
>>genes such as a black, or e chestnut.

>This is very interesting to me.  Can anyone explain to me why my horse,
>who is the output of one chestnut and one black is a bay.  I have heard
>several explanations, but still don't understand.  The black is a
>Percheron, so I am sure he didn't have any bay in his background
>(Percherons can only be black or gray).  The chestnut had a bay mother
>and a chestnut father.  The mother and father of my horse's mother had
>six foals and all were chestnut.  My other horse is the product of
>a gray mare and the same black father.  Also, I have seen several Belgian/
>Percheron crosses, and all were bay, sometimes with washed out looking
>noses and flanks.  In the winter time, my horse gets blondish hairs on
>his legs and his belly, but in summer he is a bright mahogany bay with
>black points and no white markings.

>Linda

	Hi, Linda, this is going to get somewhat complicated but bear
with me.
	There are several gene locuses at work here, your horse's 
parents were of genotype:  A- ee in the case of the chestnut and
aa E- in the case of the black.  A, means that the body color is
red or reddish and the points are black, as in a bay horse. a,
means the horse is black all over.  But another locus, the chestnut
locus can cover up the affects of 'a' black genes or 'A' bay genes.
The 'E' gene does not cover up black or bay, the 'e' gene does
cover up black or bay and makes the horse red, chestnut.  Because
'e' is recessive you need two ee's to make the cover-up work.  So
your horse's father carried the aa black genes and the E- that allows
either black or bay.  Your horse's mother carried A- which is bay
and ee which is chestnut that covers up black or bay.  Now each
horse contribute one of each gene pair to the baby.  Thus your
horse's father contributed an 'a' and the 'E' which prevented your horse
from being chestnut.  Your horse's mother contributed the 'A' which
made your horse bay instead of black and an 'e' which because it was recessive
to 'E' doesn't show up.  Thus your horse's genotype is Aa Ee and
will be able to produce blacks, bays, and chestnuts if mated to horses
carrying these genes though because of the complicated interactions
prediction of which color will come through may be difficult.  For
example if mated to another Aa Ee bay horse this horse will produce bay,
chestnut, and black in the ratio of 9 bay: 4 chestnut: 3 black.  But
if mated to a bay whose genotype is AA Ee your horse will produce only
bays and chestnuts though some of those could produce blacks.
	By the way grey is caused by another locus the 'G' causes grey
'g' causes non-grey.
	Kinda complicated but it really makes sense, honest.

				Tracy
++++++++++++++++++++++++++++++++++++++++++++++++++++

There are actually several "lethal white" genes which everyone may or
may not be aware of.  The lethal white that has been discussed extensively
on the net is a situation that occurs in paints, particularly in Overo
paints.  It is actually not due to a specific lethal gene but rather
to the overo pattern itself.  For instance unlike Tobianos you cannot
select for how much white or color you get when breeding Overos.  Overos
range from almost solid colored to nearly white or white.  It is these
white foals that suffer the intestinal problems that lead to miscarriage
or death shortly after birth.  A nearly solid Overo bred to a nearly
solid Overo can have a white or nearly white foal, conversely a largely
(though not totally) white Overo bred to a largely white Overo can
have a solid horse whose only indication that it is paint is high white
on the legs and a lot of facial white.  The key factor in how much white
is present in Overo babies appears to be womb temperature.  Also the gene
responsible for Overo coloring is recessive meaning that their must be
one contributed from each parent to make an Overo baby.  Now things get
complicated because Tobiano coloring and Sabino coloring are dominant
genes and it only takes one of those to produce their color.  Many
medicine hat paints are Sabinos.  Sabino and Tobiano nearly or totally
white babies do not die at birth unlike Overo babies.  However because
breeders have crossed all gene types together a horse that looks like
a Tobiano or Sabino may carry an Overo gene and when bred to another
horse that carries an Overo gene may produce an Overo baby, and can
rarely produce an all or mostly white Overo that will die soon after.
By the way the other way to produce the medicine hat pattern is with
a horse that is both Tobiano and Overo, so called Toveros.  
	Now to the other lethal whites that the group may not be aware of.
The Dominant White gene is a lethal white.  It is a dominant gene that
produces horses that are pure white with pink skin and brown eyes.  It
is NOT a true albino as pigment is present in the eyes, however horses
of this color are registered in the American Albino Registry, which is
now called the American White Horse Registry because of the confusion
over the genes involved.  This gene is not associated with paint color
and babies that are born white live and carry only one dominant white
gene as the homozygous form die in utero.  Only a Dominant White can
produce a Dominant White and the ratio is approximately 2/3 of the
babies will be white.
	Another color gene which is lethal in the homozygous form is
Roan.  Yes most of you don't know it but there are only heterozygous
roans out there.  The homozygous form does not exist, dies in utero
probably early in pregnancy.  
	Those horses that many of us term albino are actually perlinos
and cremellos, they are not true albinos either as they have some
pigment also.  A cremello is a horse that would have been a chestnut
if not for the cream gene (recessive), a perlino would have been a
bay.  The cream gene does not affect blacks much.  Cremellos and
perlinos are white with blue or pink eyes, the perlinos tend to have
reddish manes.  This gene is not lethal at all.

				Tracy and everybody

Just thought I'd add what I could find about the lethal white foal syndrome
that occurs in foals of overo parents.  I am getting my information from
The Horse by Evans, Second edition, 1990.

It appears that there is one locus (physical location on a chromosome
where a gene is located) that primarily controls the overo color pattern 
(this is completely different from the tobiano locus).  At this locus there
are 3 possible alleles, or different forms of the gene, which are O, o, and
oe (this should be o superscript e).  Every foal inherits from its parents
two alleles, one from each parent.  These may be the same (for example OO)
or they may be different (for example Oo).  The O allele is dominant, and
the o and oe are recessive.  If the O allele is present, the foal will not
show overo markings.

SO--A normal overo horse has a genotype of oo or ooe.  However, if a foal
has a genotype of oeoe, it has lethal white foal syndrome and will die.
Any horse that has the oe gene (whether it is solid colored and has a 
genotype of Ooe, or is a pinto and is ooe) is a carrier for the syndrome
and, if bred to another carrier, may produce a lethal white foal.

What this means is that there is no set ratio for the number of lethal
white foals produced in overo crosses.  If neither parent is a carrier,
then none of the foals will have the syndrome.  If both parents are carriers,
then 1/4 of the foals will have the syndrome, and another 1/2 will be 
carriers.  If a carrier stallion is bred to several mares, some of whom
are carriers and some of whom are not, the percent of lethal white foals
produced will depend on the percent of the mares that were carriers; the
more carrier mares, the more lethal white foals.

Sorry if this letter ended up sounding a little too much like a genetics
lecture, but I hope the information is helpful.

Sara White
94scw@williams.bitnet


Hi, in my article 3782, I made an error that I want to correct:

The color called blond sorrel is caused by the action of the P pangare
gene on an ee ff chestnut with flaxen mane and tail, not by the action
of the Z gene.  The Z gene causes the color called silver dapple and
silver dapple bay often seen on Shetland ponies.  Sorry for any 
confusion this may have caused.  

				Tracy