Other Patterns of White Hairs in Horses

This post has been updated and reissued with more photographs.

This week will be a bit of a catch-all, covering a variety of patterns of white hairs that are neither grey, classic roan, face and leg markings, or associated with white spotting. (Varnish roan, for instance, is a leopard gene pattern.) The genetics of none are well understood. Following Sponenberg, I will list and describe them here. Sorry for the lack of photos, but I haven’t even seen all of these patterns myself.

The first, frosty, may be a variant of classic roan, as it is found in the same breeds. In this pattern, the roaning is most pronounced over bony areas such as the hips, and roaning may affect the mane, tail and head as well as the body. “Squaw manes” and “squaw tails” with white hair mixed in often indicate the frosty pattern. Although there is little doubt that the pattern is genetic, it is not well understood.

“Roaned” is used to refer to horses with a scattering of white hairs not due to the roan or grey genes. It is not always possible to distinguish them from minimal classic roans, but they do occur in breeds where roan does not occur.

Rabicano horse, showing the white at the tail base. I hope to get a shot of this horse unsaddled, to show the striping on the sides.

White ticking is a much more specific pattern, involving the base of the tail and the flank. It is not progressive and may occur on any base color. Tails with the base white are sometimes referred to as “skunk tails” or “coon tails.” In Spanish the pattern is called rabicano—there are photos at the Wikipedia page. This pattern is one of the few “roan” patterns to occur in Arabians. Inheritance is thought to be dominant.

Birdcatcher spots are small white spots scattered over a horse’s body. They are named for a Thoroughbred horse, Irish Birdcatcher, who had such spots. They run in families so probably are genetic, but no studies have been carried out.

White striping is very rare in horses. The vertical white stripes may be a form of roan, as seen on the rabicano photo. Or it may simply be an accident of gestation. One striped Thoroughbred in Australia, Catch a Bird, is himself striped but is producing as a classic roan.

Finally, minor white markings may occur as a result of scarring. These are most common with freeze branding or saddle sores, but one pattern, called white lacing, is commonly due to a skin problem called reticulated leuktricia. Most often the growth of white hair in a net-like pattern over the hips and back is preceded by the formation of crusts in the skin, but not always. Both genetic and environmental causes seem to be involved. If you have an Amazon account, you may be able to see Sponenberg’s photos here.

Next week I’ll start discussing the patterns usually called paint or pinto.

Love and Lust

“Bera tried to tell me thirteen centuries ago that I’d get myself into serious trouble someday because I couldn’t tell love from lust. I went back to that memory last night. I wasn’t mature enough then to understand what she was trying to tell me. I hope I am now.”

Derik says that, in Homecoming. But what did he mean? What is the distinction between love and lust?

You might say that they are the extreme ends of human sexual relationships. At one end, love, is a relationship based on mutual caring. At the other end, lust, the relationship is basically one of power, of using another person. It seems to me that where a relationship is along this continuum is far more important than the parties involved.

Often the two are so intermixed that it is difficult to tell them apart. A bit of lust, in the form of sex drive, is probably at the heart of many human relationships. At the extreme, of course, lust is involved in rape and seduction, and the power aspect is perhaps clearest in the use of rape as a weapon of war.

It’s harder to find an example of pure love, but basically both people should feel they are getting at least as much out of the relationship as they are putting into it, and each feels happier together than they would apart. It’s probably not possible in a pure sense, as we can never know what the other person’s true feelings are.

So why does Derik, who is basically a pretty decent sort, have a problem telling love from lust?

Derik is practically sterile, and the women of his own class want nothing to do with him. All his long life, he has taken human slaves as long-term lovers. These slaves are cosseted and cared for throughout their lives.  Derik is a mind reader, but he has always felt it was immoral to read the minds of non-telepaths. The day before the statement above, he accidentally read the mind of a young slave he was trying to seduce—and who seemed quite willing to seduce him in turn—and found out what the youngster really thought of the situation.

Now he faces a dilemma. Will his powers prevent him from ever finding love?

How can we, as limited humans, tell where we are along the line between love and lust?

Fairbanks Weather

Sunrise 10:39 am, Sunset 3:19 pm for a whole 4 hours 40 minutes of daylight. We’re gaining over 5 minutes a day, now, and the sun is seven times its own diameter above the horizon at noon. Obviously there hasn’t been much wind lately, but there rarely is in Fairbanks. Won’t be long before the sun’s shining in my south windows.

We’re still running very low on snow cover, but the snow stake now says 14 inches are on the ground. Still not enough insulation for the ground, but at least a little. And yes, that photo was taken around noon, looking nearly south. From the snow caps on the sheet metal stake and the wind spinner it’s obvious we haven’t had much wind lately.

Some of my amaryllis bulbs (really hippeastrum) are blooming in the south window, thanks mainly to the timed plant lights overhead. Here in Alaska, even plants that like dark rooms need a little help in midwinter!

The forecast for today is partly cloudy, with high temperatures around 10 on the valleys and 30 on the hills. Sound backward? Well, that’s why it’s called an inversion, and they’re very common here in winter. The cold air, being heavier than the warm air, drains into the valleys, and with no solar heating of the ground to mix things up, that’s where it stays. That’s why we have little wind and (for a “pristine” area) so much potential for air pollution. Some day I’ll explain that in more detail.

The Roan Gene in Horses

This post has been updated with new photos.

Roan, like grey, is a pattern gene which sprinkles white hair over an otherwise normally pigmented animal. However, the pattern of white hair, the progression with age and the response to scarring are quite different from grey.

It should be pointed out that horsemen use the word “roan” quite loosely. In Thoroughbreds, for instance, it is used as a synonym for grey, particularly rose grey. There are several forms of roan covered by this loose usage, but the one discussed here is classic roan, which is due to the dominant roan gene. Frosty roan, varnish roan, roaned and the roaning caused by some white spotting patterns will be discussed separately.

In classic roan the head, legs, mane and tail remain fully pigmented but there is an admixture of white hairs on the body of the horse. Foals are born roan or shed their foal coat to roan, and beyond that point the roan pattern is not progressive with age. In fact, roans may darken with age. They may also change appearance with season, appearing lightest when the coat is shortest and darker in winter coat.

Corn marks (flecks of the base color) are common on roans, and scars often lack roaning.

Roan is due to a dominant gene. At one time, the gene was thought to be a lethal when two roan alleles were present at the roan locus, but more recent work has shown this not to be true. The gene itself has not been found, but it is known to be near, if not part of, the KIT locus on equine chromosome 3. There is clear linkage with chestnut at the extension locus.

Roan is quite variable in its intensity. Now and then a roan foal comes from two parents thought not to be roans, but close examination of the parents generally shows one to be a roan with very little roaning.

Roan may occur on any base color with any combination of diluting genes and marking genes. Black roans are often referred to as blue roans, bay roans as red roans, and chestnut roans as strawberry roans, but there are also references to purple roans, lilac roans, and honey roans. Further, a “red roan” could have either bay or chestnut as the underlying color, while some dark bay roans were called blue roan or purple roan. The modern practice is to put the base color first, followed by “roan.”

Roi (in Homecoming) will someday get a palomino roan mare with leopard (Appaloosa) markings—a horse overlooked by others because of her color but in fact quite a good horse. She is also a good example of the way different color genes can combine.

(The photos were taken at my cousin’s horse farm in Alabama.)

Psi and Morality

What happens when loyalties and responsibilities conflict? What is the moral thing to do?

I’ve been exploring morality to some extent in my writing. I won’t say I have the answers—there really aren’t any. But here’s an excerpt from a story set years after Homecoming was over:

“My folks hadn’t been able to teach me the morality of using my esper talents–rules don’t arise about things that are assumed not to exist.  But they had ingrained some general principles into the fiber of my being, and those general principles worked quite well with what Roi had taught me and, more recently, with what I had found in the files my mother had left behind.  Put yourself in the other person’s shoes.  Remember that ‘human’ is not just you and your relatives, or those who look like you, or who share common beliefs.  Ask yourself, ‘what would life be like if everyone behaved this way?’

“It wasn’t as easy as rules-based, black and white morality, because it required thinking.  And there had been times, both home on Earth and here on Central, when the accepted morality was immoral by the principles I believed in.  Slavery as it was practiced here on Central, for instance.  Did I even have the moral right to walk away, if I could really stop it?”

What widely accepted moral rules might be immoral in a different society or environment? Or even in our own, if looked at closely?

Snowflakes

Dendritic Snowflake

A fine, light snow has been falling today, so I took the magnifying glass out to look for cuff-link crystals. No luck–the flakes seemed to be broken-up fragments of dendrites. It’s not windy here at the ground. (It rarely is in interior Alaska.) But it must really be turbulent above the ground, to break and grind the flakes like that. Bentley would not have found this a useful snow storm–if you can call something that might give a quarter inch of snow if it goes on all day a storm!

Not at all like the storm that’s coming up in Tourist Trap, which was modeled on some early storms in the Great Plains.

Twelfth Day

On the twelfth day of Christmas, my true-love gave to me:
Twelve plates colliding,
Eleven vents erupting,
Ten glaciers surging,
Nine houses sinking,
Eight cars polluting,
Seven blizzards raging,
Six aurorae swirling,
Five solar flares.
Four chickadees,
Three mammoths,
Two ptarmigan
And a spruce hen in a spruce tree.

North Pole Weather

Sunrise 10:50 am, sunset 3:02 pm for 4 hours 12 minutes of daylight, and gaining about 4 minutes a day. That may not sound like much, but the gain is increasing every day, and over the next week we’ll gain about half an hour. I may even get to see the sun momentarily around noon.

Although December felt warm (no daily averages below 40 below, and only three overnight lows) we were actually about 12 degrees F below normal–average monthly temperature -17.9 degrees F. Four inches of snow for the month. Not much, but the snow stake in my yard is finally measuring a foot of snow depth. About time! We’re approaching the season of frozen buried pipes and wells, and we need that snow for insulation.

January is warm so far, with two of three daily highs above freezing–too warm for interior Alaska in the winter. Definitely too warm to drive, especially since the ice from that November rainstorm is still on many of the roads.

Eleventh Day

On the eleventh day of Christmas my true-love gave to me,
Eleven vents erupting,
Ten glaciers surging,
Nine houses sinking,
Eight cars polluting,
Seven blizzards raging,
Six aurorae swirling,
Five solar flares.
Four chickadees,
Three mammoths,
Two ptarmigan
And a spruce hen in a spruce tree.

The Grey Gene in Horses

This post has been updated with new photos.

Grey is frequently considered one of the basic colors of horses, but it is more correct to think of it as a pattern of white hairs. Further, it is the only pattern that changes systematically and predictably with age.

The grey locus is well documented, with two alleles. Grey is dominant to wild-type, and is due to a “4.6 kilobase duplication into intron six of the STYX17 (syntaxis 17) locus, on chromosome 25.” The practical meaning of this is that the grey gene can be tested for, and carriers of wild-type identified.

A young grey, showing how the pattern starts on the head.

Gray is a pattern of interspersed white hairs that increase in a fairly predictable fashion with age. I say fairly predictable, because there are several patterns of greying, and any genetic controls for which pattern will occur have not yet been found. The speed at which greying occurs is also quite variable, though in most cases a horse is light grey or white by ten years of age. In all cases, however, the greying begins first on the head. This is in sharp contrast to roan, where the horse is born roan and the head remains dark.

Greys can be born almost any color, but when the foal coat is shed, the horse can usually be identified as a grey. Other changes are more variable. The foal may be born with red body pigment, and remain red as the white hairs begin to appear, leading to a rose grey—often miscalled a roan. A red foal coat may shed to black, which then greys as the fraction of white hairs steadily increases. Or the foal may be born black, regardless of the genetic color, and then grey from the black.

Some greys develop a white mane and tail early. These horses generally become pure white with age, though their skin normally remains dark.

A famous grey, General Robert E. Lee’s Traveller. Good example of mane and tail remaining dark.

Others retain a dark mane and tail as the body lightens. These individuals may retain some dark shading on the legs and even body for a long time, and some never become entirely white.

Some grays are dappled at the intermediate stages—the body is covered with circular areas of lighter hair surrounded by darker circles. Others are more uniform—iron greys. Many, as they grow older, develop reddish flecks and are called flea-bitten greys. So-called blood marks—larger areas of red coat—may also develop.

Flea-bitten grey, with somewhat too much interest in the camera!

One down side of grey is that greys are particularly prone to developing melanomas. Usually these are benign, but not in all cases.

It is worth pointing out that all “white” horses with dark skin are actually grey. All other genetic mechanisms for a white coat in horses also produce pink skin.

Greys can have any of the dilution or white marking patterns in addition to the grey pattern. I had a grey and white frame (paint) myself at one point, and while he looked white with slightly darker mane and tail, the frame markings stood out sharply when I bathed him—the skin under the grey areas was black, while that under all of his white markings was pink. He eventually developed a flea-bitten pattern only over the dark skin.

Two greys are mentioned in Homecoming. The first is Derik’s grey, probably a dappled grey. Coryn took the paralyzed Roi for a ride on the second, Cotton.