Archive | Roan and roaning

More roaning and ticking

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Another kind of roaning that is often attributed to the sabino gene is the kind seen on this chestnut tobiano pony, Dexter. This has a softer look than the “laced” edges that Dexter’s sabino-tobiano stablemate Splash has.

What makes Dexter unusual, though, is that he has a solid face.

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He does have a white patch on one side of his chin which does not reach up to his lower lip, which can just barely be seen in this picture. (Because it is really under his chin it is hard to get a good image.)

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It may be that modifiers are suppressing the sabino gene to such an extent that his chin patch is all that is left. It’s also possible that this type of roaning is itself some kind of modifier, and that the white on his chin is unrelated. The commonly accepted rule is that tobiano by itself does not create white on the face, though both myself and others have had reason to question the absolute nature of that rule.  (Because that statement is nigh upon heresy to many horse color enthusiasts, elaborating on that probably merits a separate blog post at a later date.)

But it is pretty clear that this is different from true roan. Here is what true roan, when combined with tobiano, looks like. (The photo comes from Reasontobecrazy stock photography.)

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Here is a close-up of another roan tobiano.

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Notice how the roaning is evenly distributed across the spots. Now compare that to a close-up of Dexter’s hip.

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It’s also different from the roan patches that are sometimes seen on tobianos, particularly homozygous tobianos like the one below. Those tend to be rather random, whereas the roaning on horses like Dexter are concentrated around the borders of the dark patches.

Here is a close-up of roughly the same area on Dexter.

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Here is another horse showing the same kind of softly roan edges,  although he has the white face markings that Dexter lacks. (The photo comes from Citron Vert Stock.)

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Roaning and white ticking

Lazy5Belgian

Roan and sabino tend to be catch-all terms for horses that have white hairs or white markings. In the next few posts I wanted to share a few horses that a generation ago would simply have been called roan, but that have white hairs or ticking from something other than the true, dark-headed roan gene. The general convention now is to group horses like that in with the sabinos, but their actual relationship to the sabino patterns is not really known.

This American Belgian is a pretty typical roan-like pattern that is probably a type of sabino. Horses like this lack the very distinct dark points of a true roan, which are usually apparent even when roan gets combined with sabino markings.  His legs are dirty, which hide the fact that he does have white feet, but compare his legs to this true roan with flashy white markings:

The upside-down “V” formed by the dark points on his front legs, which is one of the hallmarks of the true roan pattern, is particularly visible in the video. This Belgian does not have those, even though his front socks do not extend far up his legs.

Notice, too, that the roaning not only extends into areas that would be dark on a true roan (like the face and lower legs), but it is quite uneven. His neck, for instance, shows very little roaning. Even more interesting are his hindquarters, which have patches of less intense roaning. For those artists familiar with etching to achieve roaning effects, it looks like the person doing his pattern got bored with the process by the time they reached his bum! These kinds of revertent patches are pretty common in sabino roans.

He also had an unusual roaned patch on the border of one side of his blaze.

I suspect that a lot of the Belgians (of American breeding at least) registered as chestnut roan in the last fifty years are in fact sabinos like this guy.

He isn’t that unusual, as sabino roans go. What is interesting is that it seems possible to get sabinos where there are fewer indicators that the pattern is there beyond the roaning. There are a number of instances where horses from sabino families have body roaning and a blaze, but no other white markings. In some breeds horses with all-over roaning and a blaze (or having even less white on the face) have been tested to carry Sabino1, the only form of sabino that can be tested at this point. Belgians are not known to carry Sabino1, though it’s also true that testing has not been widely done among many of the draft breeds, with the exception of the Gypsy Horse.

What we call sabino is in fact a lot of different types of patterns. Those patterns can be sorted out visually, as I did in the upcoming book, but it may be that those visual categories include different genetic colors that sometimes mimic each other.

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Rabicano versus Sabino

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Yesterday I use the pattern on this horse to discuss the way sabino can mimic rabicano. If sabino can mimic the rabicano pattern, then what exactly does a sabino-rabicano look like. Is it any different from the sabinos that have flank roaning and coon tails?

One difference might be the way the roaning organizes itself. Rabicano is known for having a brindled effect. That is a bit different from the diffused roaning that is present on the horse above. Contrast his side with this mare:

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In the areas where the white is less concentrated, the brindling is visible. (In my experience with my own mare, whose striping is pictured in the blog header, this trait is often less obvious in photos than it is in person.)

Striping

It may be that this trait can help identify the presence of rabicano as opposed to sabino roaning or even the other forms of white body ticking. Rabicanos do seem to brindle more often than other types of ticked horses, though it is hard to know if this is an exclusive trait or not, too.

Another interesting difference with this horse compared to the first one is that the tailhead is more completely white.

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Could sabino, which often boosts the white in other patterns, be influencing the amount of white on the tailhead? The frequent assumption is that rabicano is adding white tailheads to sabino patterns. This kind of effect, where sabino amplifies the white of another pattern, is consistent with what we already know sabino does.

This all illustrates the problem with identifying patterns using the tools we presently have. We have pieces of the puzzle, but we do not (yet) have a complete picture. The point at which one pattern begins and another ends is not entirely clear. To make matters more complicated, the evidence suggests that at the more minimal end there is considerable overlap. And at t the other end, the amount of white tends to hide the clues!

Both horses posted are good examples. Not only are they roaned and coon-tailed, but they each have high stockings and one blue eye. Here is the head shot from the mare. (I did not have a good, in-focus head shot of the colt in the first picture.)

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Does her blue eye come from sabino, which she obviously has? The white high on the broad side of her neck suggests she also has the frame pattern. Did that give her the blue eye? Is it proof of the presence of splash? Right now we simply do not know for sure. When there are more tests, we’ll probably be able to develop a more clear picture of just where the patterns start and end. But for now it really is just guesswork. Sometimes the breed can eliminate certain possibilities, or more clues can be found by examining production records of a given family of horses, but it is still guessing.

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