"Z" denotes the Silver, or Silver Dapples gene. Also known as "chocolate" or "taffy", Silver is one of the dilution genes, along with Champagne, Creme, Dun, and Pearl. It is not necessarily either silver or dappled, although it can be.
"Silver Dapples" was first identified in the
early 1900's in Shetland Ponies who appeared to be dappled gray, but their
coat color was stable throughout life. This color still occurs, but is less
common than the more familiar chocolate coloring.
Lewella Tembreull, an international color expert, says that this less common color
is what gave "silver dapple" its name back in the early 20th century in American Shetlands. Until the last few decades the dark shade seen in Rocky Mountain Horses and other saddle breeds wasn't even fully recognized as being the same dilution because they tend to be so much darker and not dappled. Here's a photo of Silver Crescent, the most famous historical Silver Dapple American Shetland - you can see how heavily dappled he is even in a black & white photo from the 1930's.
Lewella Tembreull, an international color expert, says that this less common color is what gave "silver dapple" its name back in the early 20th century in American Shetlands. Until the last few decades the dark shade seen in Rocky Mountain Horses and other saddle breeds wasn't even fully recognized as being the same dilution because they tend to be so much darker and not dappled. Here's a photo of Silver Crescent, the most famous historical Silver Dapple American Shetland - you can see how heavily dappled he is even in a black & white photo from the 1930's.
Here's a link to an excellent page about this color gene: Silver Dapple Morgans
Silver dilutes black to a flat brown color (which may range from a creamy chocolate-with-milk color to a deep "Weimerainer" grey-brown) and lightens the mane and tail - sometimes significantly. The horse retains a dark, nearly black mask on its face, similar to Duns (especially Black Dun, or Grullo).
Silver, or Silver Dapple, is not necessarily silver nor necessarily dappled. It is entirely unrelated to dapple gray.
Silver is called "Chocolate" in the Rocky Mountain Horse breed, and the Australian writer J. Gower refers to it as "Taffy."
Silver dapple does not effect Red pigment, but can be carried by a red horse, who can then pass it on to offspring.
Silver Bay horses are sometimes incorrectly identified as flaxen chestnuts, and Silver Black horses are sometimes incorrectly identified as Liver Chestnuts. But the dark roots of the mane and tail, combined with the darker face are diagnostic of black-based Silver. As the color becomes better known, people are recognizing it better.
Photo: Cathy Barcomb
Many horses, such as this "chestnut" Pine Nut Pony, are labeled "liver chestnut" but are really silver dapple. (the dark face is a give-away) Likewise, Sooty ("Chocolate") Palomino and Silver Dapple Bay or Silver Dapple Buckskin can look much alike.
Both The University of California at Davis and Animal Genetics, Inc. of Florida can test for the presence of Tobiano, Red, Frame, Creme, Silver, Sabino1, and Agouti (Bay). The test for Tobiano can determine whether or not a horse is homozygous of heterozygous (good to know if you are trying to breed for Tobiano).
You can download forms for these tests from their website-- follow
OR, from the Animal Genetics website
The Silver gene was believed to be confined to just a few breeds in the United States, although with recent interest, it is being identified in breeds that formerly did not recognize it. It's found most commonly in the gaited breeds of the different Mountain Horse breeds, Rocky Mountain Horses, Kentucky Mountain horses, Missouri Fox Trotters, Saddlebreds, and the Icelandic Horse. It's also common in the Welsh Pony, Shetland Pony, and Miniature Horses.
Mustangs with Silver Dapples are most likely descended from feral horses of these breeds.
Some of the Eastern Oregon herds have a high incidence of Silver Dapples, and it shows up in California and Nevada herds once in awhile, too..
Silver Dapples is fairly prevalent in the Cold Springs Herd Area of Oregon.
Photo by Andi Harmon
Silver horses at Palomino Valley from the Buck & Bald Complex in eastern Nevada
Silver wild stud horse From Cold Springs HMA, at the Burns BLM Corrals
|Silver Dapples coloring is often (though not always) accompanied by unique hoof striping - not at all like the striped hooves often seen on Appaloosas and Pintos.|
Foals are often (though not always) born with white eyelashes
Rocky Mountain Horse owned by Fran Odom
Another Rocky Mountain Horse owned by Fran Odom
Fran Odom with a "Chocolate (Silver Dapples) Rocky Mountain Horse
More Rocky Mountain Horses. Above, unknown participant at a Jerry Tindell clinic;
Jill Henderson's chocolate RMH in Walnut Creek, CA
|Silver dapples ONLY effects BLACK. It has no effect on red. (although a red horse can carry silver dapples and unexpectedly pass it on to a foal) |
If the horse is bay (black only on the points), it will turn the legs some variety of brown or tan, and the mane/tail to cream (usually with black roots). These sometimes look like flaxen chestnut.
Silver Bay Shetland pony - you can tell it is Silver and not Flaxen Chestnut by the dark roots!
Tinkerbelle, a silver dapple dun horse rescued by LipizzanLady
|Silver can mimic flaxen chestnut. But the key is the roots: Flaxen manes and tails are flaxen all the way through. Silver manes and tails have dark roots.|
Castana, a Silver Bay mustang from Sand Springs HMA in Oregon, adopted by Barbara Montgomery of Indiana
Silver Bay mustang
Tinkerbelle's darker winter/early spring coloring
Tinkerbelle in summer
Horses with the Silver dilution often have striped hooves, and often have light blonde or white eyelashes, especially as foals.
Cold Springs mustang, photo: Andi Harmon
A mustang mix of bays, silvers, blacks, and duns
|Silver horses have striped hooves (so do some others, so this isan't diagnostic in itself)|
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