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4. DESCRIPTIONS OF SOME UNUSUAL COLORS: GRULLA, CREMELLO, PERLINO
Melanie Dresser writes [22 Aug 91]: Can someone describe for me a few of the odder colors that horses come in:
According to the book _Horse Color_:
Grulla (pronounced GREW-ya) is a slate-colored horse with black points and a dark or black head. They almost always have primitive marks (withers stripe, dorsal stripe, and zebra stripes over the knees and hocks). It is a solid color with no white mixed in at all, unlike a blue roan, which clearly has white mixed in. In other words each individual hair is slaty (instead of some hairs being dark and some white, as in a roan). Overall this color looks like a field mouse, like grey-brown. It seems to be an ancient color; tarpans were grulla. "Grulla" is the Spanish word for the sandhill crane, which is a grey slate-colored bird. "Mouse dun" and "blue dun" are English terms referring to this same color.
Genetically, grulla is caused by a dun-dilution of black or seal brown. (Silver grulla is a dun-dilution combined with a cremello-dilution.)
CREMELLO I think this may be what my first pony was. He was white in the winter and a pale palomino in the summer. (Dart was the greatest pony :-))
That's cremello all right. Cremello is a genetically a chestnut horse that is carrying two c-cr dilution genes. Each gene reduces the amount of pigment in the hair shafts. One dilution gene in a genetically chestnut horse gives you palomino (or claybank dun if the mane and tail are darker), and two gives you cremello, which is basically a very pale palomino. Cremellos are not pure white but cream or off-white (or even pale palomino as your pony was in summer) with a white or off-white mane and tail and blue eyes. They are sometimes called Type-A albino but they're not true albinos.
A related color is perlino, which is a double c-cr dilution of a genetically bay or seal brown horse. (A single dilution gives buckskin, yellowish with black mane and tail.) Perlinos also have an off-white body, but typically have a rusty mane and tail, with blue eyes.
See next question for more on palominos.