Chestnut non-dun1
Non-dun1, also called nd1 is a mutation on the dun gene that causes the horse to have a dark dorsal stripe on its back.
Looks Like (Phenotype)
A chestnut horse with non-dun1 (nd1) will look like a regular chestnut horse, with a dark stripe on its back. We call this a dorsal stripe.
If the coat of the horse is not diluted, but you see a clear dorsal stripe on the back of the horse, it's very likely they are carrying nd1!
Variations
Dorsal stripes can come in different thicknesses. Some are quite thin, whereas others are bigger than the size of your thumb. Sometimes they are super straight, and sometimes they're a touch more uneven.
Behind the Colour (Genotype)
Whereas Dun (D) affects the full coat colour of a horse, Non-dun1 doesn't do that. It's a mutation on the dun gene. It is recessive to D, but dominant over non-dun2. The order of dominance is as follows: D -> nd1 -> nd1.
A horse with Dun has more than just a dorsal stripe. They have more primitive markings such as leg barring, shoulder stripes, cobwebbing or fac masks, and body stripes. On top of that, their coat is also diluted. Once you know what you need to look out for, it becomes quite easy to distinguish a horse with Dun from a non-dun1.
Related Colours
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