Black Dun (grullo/a)
Black dun is a black-based coat lightened by the dun gene. It is also known as grullo or grulla, which refers to the soft greyish tone of this colour. The body lightens to a mousegrey or steel shade, while the mane, tail, and primitive markings remain dark.
Looks Like (Phenotype)
A black dun horse has a smooth greyish or mouse grey coat with a dark mane, tail, and lower legs. The colour often has a cool tone, with faint hints of beige or silver depending on the light. You can also see clear primitive markings such as a dark dorsal stripe, leg barring, and sometimes shoulder stripes or shading around the neck.
Black duns are often mistaken for blue roans (black base coat + roan). Remember that a dun always has a dorsal stripe that continues through the mane and tail, as well as having stripes on their legs and a darker toned shoulder. Roans, on the other hand, have no dorsal stripe.
Variations
The shade of black dun can vary from light silver-grey to dark smoky brown. Some horses appear almost charcoal, while others are much paler. Foals are usually born with strong primitive markings and dark legs, and their coat may change slightly in tone as they grow.
⭐ Fun Fact
The word grullo means “crane” in Spanish, inspired by the bird’s grey feathers. Some people say grulla for mares and grullo for stallions and geldings, but either word is correct for this colour.
Behind the Colour (Genotype)
The dun gene lightens the body but leaves the points and markings dark. Only one copy of the gene is needed for the effect to appear.
Black duns are easy to recognise once you spot the stripe and cool-toned coat. You can also see how they compare to other dun shades in Horse Reality.