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# Chestnut dun
- URL: https://equinecolors.com/chestnut-dun/
- Published: 2025-11-24T13:08:57.000Z
- Updated: 2026-08-10T10:41:20.000Z
- Description: Chestnut dun (also called claybank or red dun) is a horse color caused by the dun dilution on a chestnut base. The coat is diluted, and primitive markings are present.
- Author: Hannelore Roodhooft
- Tags: Colors, Dilutions, #Import 2026-08-12 09:42

## Appearance

| Foals | ![Chestnut dun foal](https://equinecolors.com/content/images/2025/11/chestnutdunfoal.png) | [Chestnut](https://equinecolors.com/chestnut/) dun foals have a paler **orange-red**coat color and [**primitive markings**](https://equinecolors.com/dictionary/#:~:text=a%20bay%20horse.-,Primitive%20markings,-Primitive%20markings%20may). Leg primitives may be harder to see. Foals thatalso have grey often have intense primitivemarkings. |
| ----- | ----------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

| Dun on a **chestnut base** dilutes the coat to a dull **light apricot to orange-red** color. It also causes **primitive markings**. Points and primitive markings have a darker shade of red. | ![Chestnut dun](https://equinecolors.com/content/images/2025/11/chestnutdun-1.png) | Adults |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------- | ------ |

### Chestnut variations

| Flaxendun | ![Flaxen chestnut dun](https://equinecolors.com/content/images/2026/01/flaxendun.png) |
| --------- | ------------------------------------------------------------------------------------- |

### Mimics

Since there is less contrast between the coat and the primitive markings (compared to black dun or bay dun), chestnut duns may be confused with regular chestnuts or chestnut horses with [nd1](https://equinecolors.com/chestnut-nd1/).

![CTA Image](https://equinecolors.com/content/images/2025/12/Equinecolors_Icon_MagnifyingGlass-8.png) 

The ****dun dorsal** stripe goes ****through the tail**, while nd1 dorsal stripes don’t.  
Dun is more likely to cause striping at the ****back of the ears** than nd1.  
****Foals** with dun tend to have a darker ****lower face mask**, while nd1 foals have a darker forehead.

## Genetics

Chestnut dun is the result of a **chestnut base** diluted by **one of two copies of dun**. The dun (D) dilution is an allele of the [**TBX3**](https://equinecolors.com/tbx3-gene/) gene.

![CTA Image](https://equinecolors.com/content/images/2025/12/Equinecolors_Icon_DNA1-25.png) 

****Chestnut dun:**  
Chestnut (e/e) + D/\_

Dun is dominant, so horses could carry nd1 or nd2 (located on the same gene) without it being noticeable, but still pass it on. D/nd1 horses possibly tend to be lighter than D/nd2 horses.  

**Read more:**  
[Chestnut](https://equinecolors.com/base-colors-chestnut/) | [Chestnut nd1](https://equinecolors.com/chestnut-nd1/) | [Black dun](https://equinecolors.com/black-dun/) | [Bay dun](https://equinecolors.com/bay-dun/) | [Dunalino](https://equinecolors.com/palomino-2/)

[Back to Dun](https://equinecolors.com/dun/)

## Articles

1. An, T.; Dugarjaviin, M.; Han, H. ***Expression and Analysis of TBX3 Gene in the Skin from Three Locations on Dun Mongolian Bider Horse***; Genes (2024); dOI: [0.3390/genes15121589](https://doi.org/10.3390/genes15121589?urlappend=%3Futm%5Fsource%3Dresearchgate.net%26utm%5Fmedium%3Darticle&ref=equinecolors.com)
2. Cieslak J, Brooks SA, Wodas L, Mantaj W, Borowska A, Sliwowska JH, Ziarniak K, Mackowski M.; ***Genetic Background of the Polish Primitive Horse (Konik) Coat Color Variation-New Insight into Dun Dilution Phenotypic Effect***; Journal of Heredity Hered. (2021); Doi: [10.1093/jhered/esab034](https://academic.oup.com/jhered/article/112/5/436/6357767?login=false&ref=equinecolors.com)
3. 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)
4. 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)[](https://www.researchgate.net/journal/Genes-2073-4425?ref=equinecolors.com)

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