Sooty is largely a phenomenon of cryptic coloration; a horse with the Sooty factor has black tips to its body hairs, and as one goes higher on the body, the black area takes up more and more of the hair. On such a horse, the back is very dark and the belly light, adding to the camouflage effect of the coat. It also often makes the coat a darker overall coloration: Bay becomes Mahogany Bay, Dun becomes Dark Dun. The photo at left shows the barrel and flank of a typical Sooty horse, in this case a Thoroughbred Hunter.

Sooty sometimes shows extreme dappling; or it may break off into "clumps" and very rarely into Brindling.

Until recently it was thought that the Liver Chestnut was a manifestation of Sooty over Chestnut, but since Sooty countershading is uneven over the horse's body and Liver is not, these two colors are probably caused by different genes.

Sooty is extremely common in the Akhal-Teke and accounts for most of the horses labelled "Dark Bay" or Dark Dun.