October 2011


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.

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.)

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.)

Here is a close-up of another roan tobiano.

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

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.

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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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.

As genetic testing has become more common, and there are tests for more and more colors, one thing that has become apparent is that visual identification is not foolproof. Sometimes colors and patterns look alike, but prove to be two different things. The characteristic coloring of the Black Forest Horse is a good example of this.

Many have identified the horse in the picture above as a black silver. He is in fact a chestnut. In his case, there are clues that he is not actually a silver. Although the lighting in the picture makes it less obvious, his coat has red undertones that are more typical of a chestnut than a black-based silver. Even more noticeable is the red coloring at the top of his tail. Visually, it would be possible to guess he is not a silver. There are, however, a lot of Black Forest Horses that don’t give so many clues.

The Black Forest Horse was the subject of a study that determined the stallions currently standing were all genetically chestnut. (Stallions from each of the sire lines can be found here.) Even more interesting, some portion of them carried the rare alternate form of chestnut (ea) previous only known in the Asturcón and other primitive Iberian breeds. There was no correlation between the alternative chestnut allele and the distinctive flaxen-maned liver of the Black Forest Horses, though. Whatever causes the horses to be so dark, and to have such bright, contrasting manes is not currently known. It would be interesting to find out, because the horses have the same look as black silver without some of the downsides. Reports are that the Black Forest Horses keep their contrasting manes and tails over their lifetimes, a claim that is supported by the appearance of many of the older breeding stallions. Silvers, on the other hand, tend to have manes and tails that darken somewhat with age. Perhaps even more appealing, the coloring on the Black Forests is not linked with Multiple Congenital Ocular Anomalies (MCOA, formly known as ASD), an congenital eye defect thought to be caused by a gene residing close to the silver gene.

As more tests are developed, we are likely to find more and more of these look-alike colors and patterns. In the meantime, it is still fun to speculate about what might be found!

(All pictures in this post come from Wikimedia Commons.)

Cindy Evans shared this picture of one of the Knabstruppers at the Kentucky Horse Park. She’s a good horse for illustrating the term “nose-to-toes” when speaking of leopards. A nose-to-toes leopard has permanent spots over their entire body, including their face and lower legs. Those two places are important because when the leopard pattern is suppressed, those are the areas that end up dark.

Over time, though, horses with suppressed patterns like this one tend to roan back out into something that looks like a leopard. Here is a side shot of the mare Dottie that I have used in a number of previous posts.

Most horsemen would call Dottie a leopard, but notice how faint and roany the spots on her forehand and face are compared to those on her hindquarters. Her legs still have large areas of dark pigment, and of course she has the small, closely spaced spots that are typical of a supressed leopard. When she was younger, Dottie probably looked a lot more like Sprinkles (the mare pictured above.)

Compare the soft, indistinct outlines of her spots to the crisp, more defined outlines on the Knabstrupper.

Chances are this mare was born looking much like she does today, and her pattern is unlikely to change as she ages. Her whole pattern is made up of the kind of spots that do not change.

Dottie, on the other hand, only has non-changing spots on her hindquarters. The rest of her – especially her nose (face) and toes (lower legs) – changed over time to reveal a spot-like pattern. Here is a comparison shot of the spots on her hips and those on her shoulder.

Nose-to-toes leopards like the Knabstrupper are particularly desirable because they don’t change. They have clear contrast between the ground color and the spots, which most breeders (and buyers) find desirable. Horses like Dottie and Sprinkles often end up looking like leopards, but even then they don’t tend to have the same level of contrast. That said, whatever suppresses the leopard pattern is pretty common among most breeds with appaloosa patterning.

As many people have noted, the term “sabino” has become a bit of a catch-all for a lot of visually different patterns. In this way it is a little like “overo” was ten or fifteen years ago. At the time, the term overo was used to mean “not tobiano”. As the different kinds of overo have become more widely understood, many have dropped overo in favor of more specific terms.  But when something doesn’t quite fit tobiano, frame or splash, it usually gets classified – for the moment at least – as some kind of sabino.

In the upcoming book, I attempted to separate out some of the different forms the pattern we call sabino takes. Because only one form of sabino, Sabino1, can be tested at the moment, we don’t actually know if the patterns that are visually different are in fact genetically different. (We already know some things that look virtually the same can be genetically different!)  But it is true that some types of sabino can be found in some breeding groups and not others. It’s also true that some of these variations don’t fit the stereotypical “rules” often assigned to sabino. In fact, quite a number of them are likely to be misidentified as something else.

The pony mare in the picture above is a good example. Many people use high stockings and little or no face white as a clue that the horse or pony has a minimal version of the tobiano gene. (Although it isn’t the best picture, if you look you can see she had some white hairs on her forehead but no other white on the face.)  She’s not a tobiano, though. She’s a Hackney pony, which has not had tobiano in the gene pool since the early 20th century.

The one back leg does give a bit of a clue, since the white goes up the front of the leg rather than the side. This overlay illustration of a tobiano and a typical sabino pattern shows how the difference in the placement of white on the leg typical for each pattern.

That is often a good indicator, though it always has to be remembered that “typical for the pattern” is not necessarily the same thing as “always must be so.” The fact that tobiano is not part of the gene pool is a much more reliable indicator. What’s more, this kind of sabino pattern is not really uncommon in Hackneys. In the book I called these Unbalanced Sabinos, because they break the general rule that flashy white on the legs is usually matched with flashy white on the face. As these types of sabinos go, this little mare is actually pretty minimal. There are Unbalanced Sabinos that have extensive body white and very little white on the face.

Unbalanced Sabinos also break the rule posed by some writers that the sabinos have white on the chin or lips. This was my old Walking Horse gelding, Master.

He had a star and a snip, but no white on his lips or chin. Not only was it unusual to have four white legs without much face white, his leg markings were themselves unusual. The angle on this photo does not show it well, but there was a dramatic difference in the height of his front stockings, which rose in the front to his knees, compared to his hind socks. That was actually what caught my eye when I first saw him, because it is unusual for the front legs to have more white than the hind ones. He also had a belly spot half way between his girth and his sheath.

(And no, he was not a poster child for classic conformational ideals.)

One of the reason sabino variations have been on my mind was this excellent blog post by my friend Sarah Minkiewicz-Breunig. In the post, Sarah talks about the value of taking reference pictures for sculpting. Like Sarah, I am a huge believer in amassing a huge collection of reference pictures. There really isn’t any substitute for looking at hundreds and hundreds of variations of the same pattern. But even more than that, I would recommend the practice of sorting that collection. Nothing helps the eye spot trends like arranging like with like. That was how the different visual categories of sabinos were developed for the book. Stacks of sabinos were sorted into groups that were visually similar. In some cases, I pulled patterns off one body type and transferred it to another. You’d be surprised how often breed type can override your eye when it comes to spotting similarities (or differences) in patterns. Transferring the pattern over to a different body type can force you to really see things. That’s one reason why the illustrations in the book are on generic horse shapes rather than ones specific to the breed or type being discussed.

I wanted to share this photo of Gaefa, an Icelandic mare owned by Chantal Jonkergouw. Chantal was kind enough to give permission to use the photos, which really show how the eyes on some splash overos can be rather strikingly blue.

In Lorna Howlett’s book Complete Book of Ponies (1984), she mentions this tendency in blue-eyed Welsh.

Welshmen contend that this is a true sign of the Welsh Pony, and it is believed to have Celtic origin. This is undoubtedly true. Having seen true blue eyes on ponies in Wales, one cannot confuse them with wall-eyes. True blue eyes are quite lovely – deep forget-me-not blue with no loss of pigmentation.

Unlike the wall-eye – a definite fault in my opinion – blue eyes appear only occasionally, apparently lacking the prepotency of the wall-eye.

Ms. Howlett had previously explained how common those ‘faulty’ wall-eyes were, and offered a theory about the horse responsible for their proliferation. With the modern understanding of the splash overo pattern, it’s pretty clear now that whatever the difference in shade among individual ponies, the blue eyes in that breed are part of that pattern.

But it is true that the blue eyes on a lot of splashes are unusually vivid in color.

I caught this particular picture of a splash tovero with the eye partially shaded, but even so the blue is quite bright.

Here is a comparison set between the eye of the black splash in the previous picture, and a cremello. Neither picture was color corrected, though to be fair, this particular cremello had eyes that were rather greenish.

It does not seem that all splashes have vividly blue eyes, though observations along those lines are somewhat limited since we don’t have definitive answers on what is and what is not a splash. It’s also not known if splashes are unique in having these bright blue eyes. It is a tendency in the pattern, though, and one that Gaefa certainly has.

(She also has a really cool, naturally wavy mane!)