Sooty horse

At its darkest, this effect may be confused with seal brown, while in minimal forms the dark hairs may not be noticed.

[2] When there is unevenness to the sooty pattern on a chestnut-based coat, it's fairly common for the lower parts to be darker than the upper side, though the reverse is also possible.

Foods high in protein, fat, vitamin A, and trace minerals such as copper, iron, and selenium are also believed to darken the coat.

[5] A statistical analysis of 1,369 offspring of five Franches-Montagnes stallions indicated that darker shades of chestnut and bay might follow a recessive mode of inheritance.

[6] Rarely, a horse may be born with a reddish color similar to bay foals and darken over a few years to a solid brownish black or sometimes jet-black appearance.

Sponenberg & Bellone call this trait "dominant black" and discuss it in a separate chapter from sooty.