Frosty roan

FrostyRoan1

I have one last variety of roaning to share. The mare in these photos is a Quarter Horse, and is what is often called a frosty roan. Like true, dark-headed roans, frosty roans have white hairs mixed in a dark coat, but unlike the true roan the hair is not evenly distributed. Instead it tends to concentrate more heavily on the topline, including the mane and tail.  On a true roan, the mane and tail remain dark.

FrostyRoan4

There are also concentrations of white hairs where the bones are more prominent. It’s hard to see because of the shadows cast by her saddle, but notice the pale area over her elbow. This can be seen on her hocks, too.

FrostyRoan3

She also has white hairs along her nasal bones. (I suspect the small white patch on the right side is a marking, and not part of her roaning.)

FrostyRoan2

In this way, frosty roans display the opposite pattern of white hairs than a varnish roan, which tends to retain color across the bony ridges. Here is a varish face with dark nasal bones and roaning on the rest of the face.

Abby

Varnish roans typically have paler hindquarters, but the other areas where a frosty would be pale, a varnish tends to be darker. Here is the body of a varnish roan, showing how the jaw, elbows and the hocks are darker.

Mottling1

There has been speculation that the gene that causes frosty roaning, paired with true roan, may be responsible for the very pale manes and tails on some of the European draft horses. Among those breeds, black, brown and bay roans often have markedly silver manes and tails. These are often more dramatic than the ones seen in ordinary frosty roans like the Quarter Horse above. That may be because the two genes interact, or it may be that the two are similar, but genetically unrelated. (The Brabant pictured comes from Wikipedia.)

800px-Brabanter

It is not unusual for visually similar colors, like roan and frosty roan, to end up combined in a population. When breeders find a given color appealing, there is often a bias towards selecting horses that have that color – or something that looks a lot like it. That is how breeders of “golden” Saddlebreds ended up with both champagne and palomino horses in their breeding programs. Having two (or more) different genes that produce similar effects can also increase the chance that foals have the desired color, because each gene is a separate chance to get the desired look. Unfortunately for those interested in horse color research, it can also make sorting out the underlying causes a lot harder.

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10 Responses to Frosty roan

  1. Cece November 2, 2011 at 2:28 pm #

    from yrs of experience around quarter horses the frosty roans usually occur in the Go Man Go bloodlines, the white tail head (coon tailed), and roaning thruout their coat. I had a horse just like this,a grandson of Go Man Go.

  2. Threnody November 2, 2011 at 5:22 pm #

    I would love to see roan in Brabants genetically isolated. It would be great to see if they have more than one version of roan.

  3. The Equine Tapestry November 2, 2011 at 6:04 pm #

    I have wondered that, too. I was told by someone at UC Davis that the current zygosity test works for Belgians, which would suggest that it was not different from the gene in Quarter Horses. I don’t know if they were testing recent imports or not, though.

  4. Threnody November 2, 2011 at 10:44 pm #

    That is curious. I would love to see a recent import confirmed with the UC Davis test. Thanks for sharing!

  5. The Equine Tapestry November 2, 2011 at 10:49 pm #

    Technically it should not matter, since on paper at least there is no outside blood in the American breed. Roan in the one should be roan in the other, barring some kind of founder effect. But that is just on paper, and I have no idea just how well papers line up with reality in that breed. (There sure are plenty of breeds where the gap between what’s on paper and what really was used is pretty vast.) She did indicate that testing was not widely used among Belgian breeders, which I suspect is probably true for most draft breeds.

  6. horseartist2 November 3, 2011 at 4:46 pm #

    I have seen the frosty addition to classic roans in quite a few SMR horses. My new gelding would seem to be one. He also has some corn spots and reverse dappling. It would be interesting to see where those fall in the roan genetic spectrum as well.

    http://www.flickr.com/photos/simratk/6225187788/in/set-72157627725019233

    • The Equine Tapestry November 4, 2011 at 6:45 am #

      That’s a wonderful shot, Simrat! If I remember right, most of the frosty roans in the early Sponenberg books were Spanish Mustangs. I’ve also seen it on gaited horses in the south, mostly landrace “saddle horses”. It makes you wonder if it wasn’t something that came with the early colonial horses, given how it is distributed.

      • horseartist2 November 4, 2011 at 2:46 pm #

        Thanks, there are a lot more pics of him on my account. ;) Have you seen the frosty effect create white on the sides of the tail? Beau definitley has that, but I don’t see other rabicano signs, though they could be hiding.

        Do you have any thoughts on corn spots?

        The fact that the frosty effect show up in European draft horses, as well as CS/SM horses, shows that it’s pretty well distributed.

  7. Heather January 26, 2012 at 12:43 pm #

    A neighbor has a “frosty roan” AQHA stallion–he produces true roan looking offspring with solid bay and chestnut mares. I started wondering about him when I first seen one of his very roan looking foals out of a solid bay mare. I’ve had some good hands on looking at this stallion as well, and it’s hard to see (the fact that he is also buckskin doesn’t help…but at any given point, you wouldn’t be able to tell he is roan unless you got SUPER close and looked for his few white hairs)

  8. Kristina Pry February 16, 2013 at 2:42 pm #

    Have any frosty roans been tested for roan zygosity to at least see if the genetic markers are the same as classic roans?