> ## Content Index > Fetch the complete content index at: https://equinecolors.com/llms.txt > Use this file to discover other available public pages before exploring further. # Characteristics of dun - URL: https://equinecolors.com/characteristics-of-dun/ - Published: 2026-04-16T07:56:02.000Z - Updated: 2026-08-10T10:56:49.000Z - Description: Dun is a horse color dilution that lightens the coat, with darker areas called "primitive markings". Not all primitive markings are always present on each horse, and the degree to which they are expressed can also differ. It can also cause frosting. - Author: Hannelore Roodhooft - Tags: Blog, Dilutions, #Import 2026-08-12 09:42 ## About dun Dun is thought to be the wild-type or **"original" color** of horses and is also found in other equines such as Przewalski horses, zebras, and asses (donkeys). Because of this, dun is believed to have an important role in camouflage. The [gene](https://equinecolors.com/dictionary/#:~:text=in%20each%20pair.-,Gene,-A%20gene%20is) responsible for dun is **TBX3**. There are three known [alleles](https://equinecolors.com/dictionary/#:~:text=the%20DNA%20sequence-,Alleles,-Different%20versions%20of) of this gene: **D** (dun), **nd1** (non-dun1) and **nd2** (non-dun2). | **Alleles** | **Effect** | | ----------- | ---------------------------------------- | | D | Dun: diluted coat and primitive markings | | nd1 | Primitive markings | | nd2 | No dilution or primitive markings | The dun allele (D) is [dominant](https://equinecolors.com/dictionary/#:~:text=Influence%20Coat%20Color-,Dominant,-Allele%20%28written%20in), so any horse that is D/\_ will be dun. Most domestic horses nowadays are nd2 or nd1, even though these are technically mutations! ![CTA Image](https://equinecolors.com/content/images/2026/03/Equinecolors_Icon_DNA1.png) When we write, for example, "D/\_", this means the "\_" could be any allele: D/D, D/nd1 or D/nd2. The D-allele leads to a "normal" TBX3 gene. In the areas where TBX3 is active, it **dilutes** the coat. It causes only one side of the hairshaft to have pigment in it, making it look lighter as a result. The head, lower legs, mane, and tail stay mostly undiluted. Dun also causes **"primitive markings"**, a group of dark coat markings. TBX3 is not expressed in these dark and undiluted areas, which is why they aren't lightened like the rest of the coat. Another possible dun characteristic is **"frosting"** in the mane and/or tail. In this post, we'll go over the different dun characteristics, like all the possible primitive markings and frosting, and highlight them with real-life examples. Keep in mind that horses may not have all of the characteristics at the same time, and the degree to which they are expressed can also differ between horses. > You can read the full Equinecolors dun article [here](https://equinecolors.com/sunshine/). ## Primitive markings | Dorsalstripe | ![Dorsal stripe](https://equinecolors.com/content/images/2026/04/ELP-dorsalstripe.jpg) Sorraia horse, Portugal @Equine legacy Project1 | The most defining and visible dun marking.It is always present, but can be hidden by e.g.white patterns.A dorsal stripe is a long, **dark line** running fromthe **mane**, over the **spine**, all the way **through** the **tail**. Because of this, mane/ tail will have adark centre; think of the typical Fjord mane.The width of the stripe can vary, and somedorsal stripes also have fishgrate-like lines extending out from them. | | ------------ | -------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Shoulderstripes | ![Shoulder stripes](https://equinecolors.com/content/images/2026/04/ELP-shoulderstripe-1.jpg) Sorraia horse, Portugal @Equine legacy Project1 | A **diagonal stripe** on the **shoulder** area.It can vary from a light shadow or smudgeon the withers to multiple stripes up tothe neck. | | --------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- | | Bidermarkings | ![Dorsal stripe](https://equinecolors.com/content/images/2026/03/animals-bidermarkings.jpg) Adapted from Smith et al., Animals (2026), CC BY 4.0.2 | Unique, cobweb-like dark **patchy areas**on the **shoulder**, present in breeds likethe Mongolian Horse. | | ------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- | | Leg stripes | ![Primitive leg markings](https://equinecolors.com/content/images/2026/04/ELP-legmarkings-1.jpg) Sorraia horse, Portugal @Equine legacy Project1 | Leg markings or stripes, also called leg barring,zebra or tiger stripes, are **horizontal stripes**on the legs, around the **knees and hocks**.The stripes can sometimes also form patchyareas on the legs. | | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | facemask | ![Face mask](https://equinecolors.com/content/images/2026/04/ELP-facemask.jpg) Sorraia horse, Portugal @Equine legacy Project1 | **Darker color** or shading on the **head**, usually on the lower face and/or nose bridge, that canrun up to the eyes. | | -------- | ------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------- | | Cobwebbing | ![Cobwebbing](https://equinecolors.com/content/images/2026/04/ELP-cobwebbing-1.jpg) Sorraia horse, Portugal @Equine legacy Project | **Dark stripes** or lines on the **forehead** that, as the name suggests, can look like aspiderweb on the head. | | ---------- | ---------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- | | Eartips | ![eartips](https://equinecolors.com/content/images/2026/04/ELP-eartips2.jpg) Sorraia horse, Portugal @Equine legacy Project1 | The eartips of dun horses can be darker in colorand/or show some striping. In some cases, theears can also have pale/white tips. | | ------- | ---------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- | ## Skewed dun | Skeweddun | ![Skewed dun](https://equinecolors.com/content/images/2026/03/BarbaraDLivingston-SharpTrilogy.jpg) Sharp Trilogy, Quarter Horse @Barbara D. Livingston3 | They're often called "brindle", but most of thetime stripey coat patterns like this are the result of "skewed" colors or white patterns(brindle1 exists in horses, but that is a coattexture mutation, rather than a color). In skewed dun, **the darker hairs** are **skewed**along the **"lines of Blaschko"**, resulting injust a few to a full coat of dark stripes.These lines represent the path along whichcells grow and migrate during development.Although they are usually invisible, every horse has these lines! | | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ## Frosting | Frosting | ![Frosting](https://equinecolors.com/content/images/2026/04/ELP-frosting--2--1.jpg) Sorraia horse, Portugal @Equine Legacy Project1 | Frosting refers to **pale/white hairs** in the **mane** and/or head of the **tail** of dun (or buckskin) horses. | | -------- | ----------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- | ## Dun vs. nd1 Dun and nd1 can both cause primitive markings. The difference is that **dun dilutes** the coat, while nd1 does not. The primitive markings on nd1 horses also tend to be less intense. A prime example of this (and a good way to tell the difference) is that **dun dorsal** stripes run all the way through **the tail**, and the tail is darker in the middle. **Nd1 dorsal** stripes, on the other hand, do not. | nd1 | ![nd1](https://equinecolors.com/content/images/2026/05/nd1-dorsal.jpg) @Hannelore Roodhooft | Dorsal stripes caused by nd1don't run through the tail. | | --- | ------------------------------------------------------------------------------------------- | ------------------------------------------------------- | ## Dun vs. buckskin Bay dun horses are often confused with buckskin horses. Their coat colors can look quite similar: both can have a yellow-to-golden coat, with dark points and frosting. However, **dun** horses also have **primitive markings**, while buckskins do not! [Back to Blog](https://equinecolors.com/blog/) ## References All images used with permission. 1. Equine Legacy Project**:** [https://equinelegacy.minhdanvu.com/](https://equinelegacy.minhdanvu.com/?ref=equinecolors.com) The Equine Legacy Project is a conservation project raising awareness for endangered and rare horse breeds, powered by three women 2. Image adapted from: An, T.; Dugarjaviin, M.; **Differential Expression of MITF, WNT3A, SLC7A11, and EDN3 in the Shoulder ‘Bider Marking’ of Dun Mongolian Horses;** *Animals* (2026); Doi: [10.3390/ani16060967](https://doi.org/10.3390/ani16060967?ref=equinecolors.com) Licensed under **Creative Commons Attribution 4.0 International (CC BY 4.0)**. Changes: Image cropped for clarity 3. Barbara D. Livingston: [https://barbaradlivingston.photoshelter.com/](https://barbaradlivingston.photoshelter.com/?ref=equinecolors.com) 4. Imsland, F., McGowan, K., Rubin, C. J., Henegar, C., Sundstrom, E., Berglund, J., Schwochow, D., Gustafson, U., Imsland, P., Lindblad-Toh, K., Lindgren, G., Mikko, S., Millon, L., Wade, C., Schubert, M., Orlando, L., Penedo, M. C., Barsh, G. S., & Andersson, L.; **Regulatory mutations in TBX3 disrupt asymmetric hair pigmentation that underlies Dun camouflage color in horses**; Nature Genetics (2015)*;* Doi: [10.1038/ng.3475](https://doi.org/10.1038/ng.3475?ref=equinecolors.com) 5. Masuda M. Tsunoda J., Nomura H., Kimura N., Altangerel G., Namkhai B., Dolj U., Yokohama Y.***; New Primitive Marking (Bider) in Mongolian Native Horse and Equus przewalskii;*** Journal of Equine Science (2007); Doi: [10.1294/jes.18.145](https://doi.org/10.1294/jes.18.145?ref=equinecolors.com)