Dun Factor Markings
Please note that all of the text information on this page was
originally composed by me unless otherwise referenced,
and was typed with great thought. I have read books and many educational
web sites to contribute to my knowledge base. Some of the content was
created in the late 1990's, and may need to be updated. With 300+ pages in this
web site, I can't remember which pages need updates all the time. If you see
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here to learn
There is often a great difficulty determining a horse's
color when it comes to dilution genes, especially as foals. Because
of countershading, sooting, and other color modifications, foals are often
mislabeled as duns or grullas when they really should be registered as
buckskins or blacks. See the bottom of www.grullablue.com/grullocolor.htm
for photo examples of foal coat colors that can easily be mistaken for
But as horses shed their foals coats, it should become
more readily apparent if they carry the dun factor trait or not.
Photos below show some of the dun factor traits to look for. Not all
dun-factored horses will have all traits, but in my experience, all of
them have had the CLEAN and CRISP dorsal stripe and the ear tips.
Why is it important? Why should anyone care?
Because if a horse is being sold and is misrepresented (purposefully or
accidentally) as being one color and it truly isn't that color, then it
reflects badly on the seller when the truth is found out. It can also be
very disappointing to the buyer. I have
heard of too many instances of this...both purposeful and accidental, that
have both hurt seller reputations and damaged buyer's pocketbooks.
The largest case occurs when a buyer pays a higher price for a rare color,
such as grullo, only to have the horse shipped home to see for the first
time in real life and find that it is a buckskin, black, smoky black, or
|Dorsal Stripe: This is a
required dun factor marking. If a horse lacks this, then it is not
a dun or grullo. The dorsal stripe is a dark stripe running from
the poll to the dock of the tail. It shows up along the horse's
spine. Though it may have barbs extending off of it, it will have
CLEAN and CRISP edges, and won't "gradually fade into the
body color of the horse." It will also be an
"intense" color, and does not fade away in the
summer. It should not be a mixture of body hair color and
dark hair color, but should instead be uniformly dark throughout.
Dorsal stripes on red dun (left) and grullo (right)
|Ear Tips: The ear tips are
generally the same color as the dorsal stripes. Sometimes the
entire ear will be rimmed or edged, but the actual ear tip is when
the top half or third is dark on the back of the ear. All duns/grullos
that I have seen have had ear tips.
NOTE: Dark "rims" around the ears (viewed
from the FRONT) are NOT dun factor markings. These dark rims are
common in bays, buckskins, etc. and are NOT caused by dun factor.
See the diagram at the right for an example.
Ear tips on a foal, left.
The drawing at the right shows ear tips (top 2 sets of ears), which
ARE dun factor related.
The bottom set of ears shows ear rims which
are NOT necessarily a sign of dun factor.
|Leg Barring/Zebra Stripes:
These are horizontal tiger stripes that appear on the legs,
usually around the knees and hocks. These are not always
present on dun-factored horses.
|Shoulder Stripe & Shadow:
A stripe or a shadow coming off the dorsal and crossing down the
withers toward the ground. Some are thin, some have multiple
stripes, and some are just shadows.
|Face Mask: Duns of all shades usually have a
darker mask on the front of the face or over the bridge of the
nose than on the rest of their
|Mottling: Some duns will show
mottling on the arm and shoulder or gaskin and stifle. Mottling
appears as dark splotches about the size of peas when viewed up
close, or like tiny reverse dapples.
Mottling (above the leg bars) on a dun
|Neck Shadow: Similar to
shoulder stripes at times, neck shadowing can be definite striping
to sooty-looking shading coming down off
the top of the neck.
|Frosting: Frosting in
the mane can be subtle or very pronounced, as on this grulla
mare. Frosting is light coloring to the mane hair on the
edges of the mane. The "main" part of the mane is black, but the
hairs that run down the sides of the mane are light.
Silver grullo with frosting. Zebs Blue Revenue, left.
Frosting on a mini, right ("Little Foot")
|Cobwebbing: Stripes that
resemble a spider's web on the forehead of a dun-factored
horse. Cobwebbing is very difficult to catch with a camera.
Click to view close-up shots of forehead cobwebbing.
|Dark Points: The legs will
usually be darker than the body...similar to the mane/tail and
Dark points on a red dun: note that the legs, mane, tail,
and face are not diluted (lightened) by the dun dilution gene.
|Barbs off the dorsal stripe:
Some dorsals will have barbs that extend perpendicular to the
stripe and head down the rib cage. These are not required,
and vary in length.
Barbs on a dorsal strip
|Guard Hairs: Some duns will
have light-colored hairs at the base of the tail that can extend
down the sides of the tail, called "guard"
hairs. They appear to be different than the white
"skunk tail" that is associated with some roans' and rabicanos' white
Note the light hairs on the sides of the tail at the top.
|Silver Grullo foal eye color:
This isn't a dun factor characteristic, but I thought I'd throw it
in. We've had several foals that had a sire or dam who carried
the cream gene. We feel that blue-gray eyes like this at birth
indicate that the foal likely carries the cream gene. Some grullo
foals with the cream gene end up silver, but not all of them do.
Countershading (NON-dun factor striping)
following table contains photos of horses that are NOT dun-factored
horses. "Countershading" is a form of striping that is probably a
remnant of primitive camouflage, but which is not the same as dun
striping. It is not a dilution, and may only be visible on young
horses. Some horses will retain some countershading for their whole lives,
but it is far less distinct and contrasting with surrounding colors when
compared to dun factor striping.
Not Dun Factor
This bay foal has a good example of a countershading
stripe. There are NO duns in his background, so we know he is
a bay with countershading. Most likely, his stripe will
disappear when he sheds off as a yearling.
Not Dun Factor
A black foal with countershading-caused dorsal and shoulder barring.
Click here for proof that this filly
is not dun factored.
Not Dun Factor
A black foal with countershading.
Not Dun Factor
DNA tested buckskin with NO dun factor gene.
Not Dun Factor
This foal is bay or bay roan, but has an amazing countershading
stripe and shoulder patch that will disappear over time. He can not
be a dun, as he does not have dun factor genetics behind him in the
Not Dun Factor
Super pictures of buckskin foals with countershading stripes that
are not caused by dun factor. Notice that the dorsal on these foals
stops abruptly at the top of the tail. The foals also do not have
Neither dun factor nor countershading.
These are not stripes. This is a hair pattern that shows up best on
black and blue roan foals' back legs, and that many people mistake for leg
bars. It is not, and is probably a trick of lights on waved/curly hair.
Not Dun Factor
Countershading stripes on black and smokey black foals' legs are
fairly common, but disappear over the first year.
UC Davis Information about Dun and Non-Dun Stripes
Three variants in DNA sequence explain phenotypes
(how horse "look" to the eye) related to Dun dilution:
D (presence of dun
dilution and primitive markings)
nd1 (not Dun-diluted;
primitive markings are present but expression is variable).
Think of "nd" meaning "not dun."
nd2 (1,617 bp deletion,
not Dun-diluted, primitive markings absent).
Think of "nd" meaning "not dun."
With respect to variant interactions, D is
dominant over nd1 and nd2; nd1 is dominant over nd2.
The VGL offers a DNA test that will provide
information for both dun dilution and the primitive markings.
Click here for more information.
Show What You Know!
The pictures below show examples of horses that may or may not
have dun factor. Can you get the colors correct by looking at these
Interesting picture, below. It shows how hard it
is to guess horse colors when you can't see "the whole picture"
through multiple photos, seeing the horse in person, and/or knowing
the sire/dam genetics.
Without looking anywhere else but at this photo,
what colors do you think these two yearlings (below) are?
Click the photo above to enlarge it.
Photo will open in a new window.
to see if you got it right!
Click the photo to view it full sized.
3 dun factors, one countershading (non-dun).
Can you tell which is NOT a dun factor dorsal stripe?
2 dun factors and one non-dun striping. Which isn't a dun stripe?
for the answer.
What color is YOUR horse?
If you are trying to determine the color of your foal or
horse, keep this in mind:
The most common mistake people make
trying to force others to believe
that their foal or horse is the color
they WANT him to be.
Many, many people have asked me over the
past few years what color their foals were, and then have refused to
accept my opinion because they so badly wanted their foal to be a
different color. As you try to figure out your foal's color, leave
your personal preference out of it....go by the facts first.
Hopefully, you'll be pleased in the end! But if not (for example, if
you wanted him to be a grulla and he turns out to be a sooty buckskin),
take comfort in the fact that you know the truth and can educate others
about the differences between similar colors.
Click here to Request help determining
your horse or foal's color
What color will the foal be? The dun link
covers the foal coat colors and colors at maturity of the dun gene
(red dun, dun, and grulla). http://members.aol.com/battyatty/dunfoal.htm
Variations of buckskins The creme link
covers buckskins. http://members.aol.com/battyatty/sooty.htm
It has a couple of pictures of sooty buckskins that are mistaken for
grullas, but are not grullas. Remember, buckskins are NOT the
same as duns.
Examples of Grullos and Introductory Color Discussion
Is he a buckskin or a dun? This link tells you
the difference between a buckskin and a dun/grulla/red dun. http://members.aol.com/battyatty/buckdun.htm
Does your horse have a dorsal stripe, but neither
of his parents did? IMPORTANT LINK. This one talks
about markings that are similar to dun dorsal stripes, but not the
same. These markings are responsible for a lot of horses being
called dun or grulla who really are not. http://members.aol.com/battyatty/count.htm
http://tenderquarterhorses.tripod.com/tqh_020.htm to learn about
sootiness/smuttiness and countershading.
Dilution genes...dun, creme, champagne. http://www.ultimatehorsesite.com/horsecolor/dilutes.html
This site has photos and descriptions of different dilute
colors. Some of her photos border on mislabeled "in my
opinion," (mainly the grullo shades), but her
descriptions/definitions appear to be pretty well founded.
More about dun factor genetics! http://www.thelinebackmorganstud.com/
The Champagne gene...not creme This link
tells about the champagne gene, which causes buckskin-like colors.
Please visit our web site at www.grullablue.com
or Sharon Batteatte's site at http://members.aol.com/battyatty/dunfoal.htm
or e-mail me at email@example.com
for more information or more contacts.
Color and Genetic Testing Labs
There are many laboratories in the US and around the
world that do horse color testing, disease testing, etc. When you choose a
lab, make sure it is a reputable one! There are several university-related
labs, which I recommend, and many private labs (some of which can NOT be
recommended!). Here are a few
I'm familiar with:
Animal Genetics, Inc.
Pet DNA of Arizona:
http://www.petdnaservicesaz.com/Equine.html ONLY tests for Brown in horses
PROCEED WITH CAUTION IF YOU CHOOSE TO
USE THIS LAB, BELOW, in my opinion:
DNA Diagnostics (aka Shelterwood Labs, and also affiliated somehow with
Diagnostics/Shelterwood Labs offers a test for multiple
characteristics at one price.
I had seen a fair bit of chatter online about how they cash the checks and
don't give the results of the test. So, I tested them by paying for three
horse tests. Guess what...they sent back two of my horses' test results and
after 4 1/2 months, the third was still missing in action! Repeated phone calls and
e-mails were ignored by the lab. Finally, five months after the test, someone
gave me the results for the third horse.
If you choose to use this lab, my
opinion is to only send them as much money as you are willing to lose, in case
you don't receive your results. Update: A friend just called that used
this lab and she still hasn't received her results after many months of waiting,
phone calls, and e-mails. 3/2010. I know of another horse that tested homozygous
for black that is not homozygous, as he has produced sorrel and palomino
foals. In both cases, Shelterwood does not return their repeated phone calls.
REFERENCES: This information was pulled out
of my own brain in 2003, but my brain gained its information over
the course of many years from internet sites, discussions with color
genetics gurus, and from Equine Color Genetics, by Dr. P.
Sponenberg, Ph D. Special thanks to Linda Coehoorn, Kris Enloe,
IBHA, and Sharon Batteatte for helping me understand the genetics of the
dun and grullo colors in the mid 1990's.
How To Donate Your Educational Photo:
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