definition of grulla horse
The dun gene also produces light guard hairs in the mane and the tail. Grullo or grulla is a color of horses in the dun family, characterized by tan-gray or mouse-colored hairs on the body, often with shoulder and dorsal stripes and black barring on the lower legs. In this coloration, each individual hair is mouse-colored, unlike a roan, which is composed of a mixture of dark and light hairs.