Smoky black
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Smoky black is a hair coat color of horses in which the coat is a few shades off true black. For centuries, smoky black has been mistaken for faded black, dark bay or brown, grullo or even liver chestnut. Smoky black is a rather uncommon coat color, produced by the action of a single copy of the cream dilution gene on an underlying black coat color, often a byproduct of breeding for more popular colors such as buckskin. Therefore, smoky black is a member of the cream family of coat colors, and so may be found in any horse population that has cream colors such as palomino, buckskin, perlino and cremello.
A smoky black horse, when crossed on another horse carrying the cream dilution, may produce a smoky cream, a cream-colored horse which is visually difficult to distinguish from a perlino, but can be identified through DNA testing.
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[edit] Visual identification
Smoky black foals must always have at least one parent with the cream dilute gene and a parent that carries the "E" extension gene associated with black coloring. While a smoky black parent carries both genes, so do buckskins. A smoky black could also be produced by breeding one horse with only the cream dilution, such as a palomino, to a horse carrying the extension gene, but no cream dilution, such as a black or bay. As foals, smoky blacks are typically quite silvery, and may be mistaken for grullos, especially when born with primitive countershading. Key to identification is that smoky black foals are sometimes born with blue eyes[citation needed] and may have reddish tufts of hair in their ears.
While it superficially resembles other coat colors, experienced horse persons usually detect something "off" about the coat of an adult smoky black. The darkest shades among smoky blacks are almost indistinguishable from true black but for a slightly burnished look often chalked up to sun bleaching, and for reddish hair inside the ear. The palest can be mistaken for bays or liver chestnuts, especially if exposed to the elements. Smoky black coats tend to react strongly to sun and sweat, and many smoky blacks turn to a chocolate color with particularly reddish manes and tails. Bleaching due to the elements means that the legs retain their color better, and can take on an appearance of having dark points like a bay horse. Smoky blacks, however, will lack rich red tones in the coat, instead favoring chocolate and orange tones.
One way to visually identify some smoky blacks are by the eyes, which may be amber even at adulthood.[citation needed]
[edit] Smoky black mimics
- Liver chestnut: The palest, most evenly-bleached smoky blacks may mimic the darkest shades of chestnut. Chestnuts do not have true black tones in their coats, and will usually reveal reddish character around the fetlocks. Smoky blacks usually have uniformly black legs. Furthermore, chestnuts do not possess amber eyes.
- Classic champagne: Paler smoky blacks with amber eyes may be confused with the activity of champagne on a black coat. Champagne horses have pinkish, freckled skin and green, hazel or amber eyes, as opposed to the dark skin and brown or amber eyes of a smoky black.
- Dark bay: When smoky blacks fade from exposure to the elements, their legs usually retain their color, giving them the appearance of a brown horse with black points. However, bay horses lack amber eyes, and the brown coat of a bleached smoky black recalls orange rather than red or mahogany.
- Grullo: Grullo is the action of the dun gene on black. Typically, grullo coats have cool slate hues as opposed to warm orange-brown tones. Furthermore, grullos have dun characteristics such as bold dorsal stripes and leg bars.
[edit] Genetic identification
Genetically, smoky blacks are black horses heterozygous for the cream gene. The mutation that produces the cream colors is on the MATP gene on equine chromosome 21 (ECA21), and is an incomplete dominant trait. Incomplete dominant traits differ from recessive traits, which are only "visible" in the homozygous state, and simple dominant traits, which are just as "visible" in the homozygous or heterozygous state. Instead, the MATP mutation is visible the heterozygous state, but more so in the homozygous state. The difficulty in identifying smoky blacks has led some to describe black as "masking" cream, however smoky blacks are more properly termed "cryptic creams."
The location of the cream gene was published in 2003 and there now exists a DNA test for the cream gene.[1] This test enables breeders to identify cryptic creams such as smoky blacks, dark palominos and buckskins, and creams whose coats are obscured by the action of the gray gene or pattern genes such as pinto.
[edit] References
- ^ "Horse Coat Color", Veterinary Genetics Lab, University of California, Davis. Web Site accessed May 29, 2008
- Smoky Black Colorful Morgans. Accessed May 28, 2008.
- Color and Markings Guidelines Accessed May 28, 2008.
- Smoky Black in Icelandic Horses Accessed May 28, 2008.
- Mariat, Denis; Sead Taourit, Gérard Guérin (2003). "A mutation in the MATP gene causes the cream coat colour in the horse". Genet. Sel. Evol. 35: 119-133. INRA/EDP Sciences. doi:.
[edit] See also
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