Primitive markings, also called countershading and non-dun1, are dorsal stripes, leg barring, shoulder stripes, and cobwebbing/spiderwebbing.

There is a genetic test for primitive markings, which is called non-dun1. Research on primitive markings in horses released in 2015 discovered non-dun1. Dun (D) is the original color of horses and they have primitive markings and are diluted. Non-dun1 horses have primitive markings but are not diluted (d1). Horses without any primitive markings have a mutation called non-dun2 (d2). d1 and d2 are recessive and can appear to skip generations. d1 is dominant over d2. D is dominant and cannot appear to skip generations.

Foals often have primitive markings that is later lost after the foal coat is shed. This is presumed to be a form of camouflage.

Sooty buckskin with a dorsal stripe. Zebe Beebe Bella, 2010, Picture by Amanda Geci.

Bay with dorsal stripe. Unci, Picture by Amanda Geci.

Bay tobiano with dorsal stripe. Tunie, Picture by Amanda Geci.

Dark flaxen chestnut splash with dorsal stripe. Surfer Dude's Riptide, 2016, Picture by Amanda Geci.

Chestnut mare and black foal with dorsal stripes. Chincoteague Island Major and Diamond's Jewel, 2014, Picture by Amanda Geci.

Chestnut foals with foal dorsal stripes. Misty's Red Dawn and a wild foal, 2011, Pictures by Amanda Geci.