Tag Archives | pintaloosa

Leopards, Cat Tracks and Beltons (Part 1)

Images of leopard appaloosas with Dalmatian dogs are always eye-catching. Certainly they can look quite closely matched, like this Polish Malopolski and his buddy. Even so, the patterns in the two species are very different in terms of what is really happening to the pigment on the animal. That’s probably off in the weeds for most owners and breeders, but for artists the distinction is actually pretty important.

This touches on one of the reasons why artists who develop an interest in horse color often have such a different perspective. Usually the kind of information a breeder needs is predictive. That is, they need to know what might likely result from crossing this to that, or what they might need to cross if this particular end result is what was wanted. What artists need to know isn’t about prediction nearly so much as it is about possibilities. Not so much what might happen, but what could happen – even far-out-there, not-very-likely, could happen. That’s because artists often want to add something for interest or for composition. For those producing realistic art, that has to be done within the constraints of what is possible. It doesn’t necessarily have to be likely, but it does have to be possible. This unique perspective became apparent to me a number of years ago when I gave my first presentation on horse color. In the question and answer period afterwards, someone in the audience asked if a horse could be both dappled and fleabitten at the same time. It was clear that was not the sort of question my fellow presenter, Dr. Sponenberg, often heard. But it is precisely the kind of question that equine artists ask all the time. Scientists might not notice this kind of detail on an individual horse, but for someone who paints horses, this kind of information – does this happen with this? – has a lot of practical value.

So why do artists need to understand the process behind appaloosa patterns? Spotting is a useful tool, because it breaks up positive and negative space. It makes the horse more visually interesting. If you are particularly clever, it can be used to draw the eye in a way that works with the composition, or to hide flaws. But spotting doesn’t just happen anywhere. It follows rules, and those rules depend with what is happening with the pigment. Understanding the underlying mechanism makes it far less likely that you’ll add some interesting detail that isn’t realistic. When dealing with rare combinations of colors and patterns, it might be difficult to find a reference image to consult. Knowing the process can tell you if there is a reason to bother looking in the first place, because it tells you what is possible. (And when you wing it without a reference, the knowledge will make for more reliable guesses.)

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“Trouble”, sculpted by Sarah Minkiewicz-Breunig and glazed by Lesli Kathman.
In the collection of Melissa Gaulding.

This is a ceramic collectible with the kind of spotting (often called cat tracking) seen in homozygous tobianos. It’s a really popular effect. In my normal job (the one I have when I am not trying to get a horse color book to press), I have produced quite a number of these. The problem comes when this gets confused with leopard spotting, and most especially what happens when leopard patterns are combined with the tobiano pattern. That brings us back to the image at the beginning of the post. These three images – the leopard, the Dalmatian, and my ceramic foal –  represent three very different scenarios in terms of the underlying process. I want to take each, one at a time, and explain how they are different despite looking so similar.

This is the typical nose-to-toes kind of leopard. Most people would think of this as a white horse with black spots that have been superimposed on top. That’s not really accurate. From a genetic standpoint, this kind of horse is a two-step process. First she has inherited a gene that progressively adds white hairs to the coat. Those hairs, over time, are going to produce the fairly distinctive pattern known as varnish roan. If the pony in my illustration just had that first gene, she would look like a black version of this pony.

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That first gene, known as Leopard Complex, sets things up for leopard but it doesn’t make leopard patterns itself.

That happens when the horse inherits a separate patterning gene in addition to Leopard Complex. In this case, that patterning gene is called Pattern1. What Pattern1 does is take the white from Leopard Complex and amplifies and organizes it. So while our horse looks like she is white with spots, it is perhaps more helpful to think of her as a horse that was roan, but Pattern1 has now taken that mixture of white and dark hair  and reorganized it. Underneath the white hair, what that horse may look like is closer to this.

This is what the underlying skin looks like. She probably does have some truly white skin in the area where a blanket pattern would go. Pattern1 does amplify the white, after all. But under it all she isn’t really a white horse, at least not in the sense that most people would think of as true white. She is more like a roan horse that has been modified a bit. That’s why even nose-to-toes leopards have faces that are shaded much more like a grey than a cremello, because for the most part the face has dark skin, not pink skin. And that is why a pintaloosa looks like this:

The true white areas of the tobiano pattern cover over the appaloosa pattern. The spots from the leopard pattern don’t spread over onto the tobiano pattern because the process with Pattern1 isn’t “add dark spots to the white”, it is “organize the roan into spots.” So the spots don’t happen where the tobiano pattern already took all the roan away. Without the color there in the first place, Pattern1 has nothing to work with.

Of course, if we moved our tobiano pattern out a bit, encompassing more of the dark skin and butting it up close to the “blanket” skin, we could probably get something that looked a bit like the leopard spots migrated over some of the tobiano.

Even so, the spotting is still concentrated in such a way that shows it is an appaloosa pattern with a tobiano pattern layered over the top of it. The spots on the flanks might look like they are in the tobiano white, but really they are just in an area that was already white from the action of the Pattern1 gene. The action is still the same. The tobiano is there adding true, pink-skinned white on the horse, and underneath it Leopard Complex and Pattern1 are just doing their thing.

Even with the tobiano bumping up to the pink-skinned areas of the leopard pattern, it still looks different from the kind of spotting that comes from a horse having two copies of the tobiano gene.

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This is a (presumably) homozygous tobiano with cat tracks. Whereas Leopard Complex is a roaning process that Pattern1 takes and organizes into the leopard pattern, this type of spotting is more like a not-entirely-successful attempt to add some more color to a horse that already has large patches of color. Unlike the existing spots, which are large and opaque, these new spots are small and vary in opacity. Some just come through in specks.

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Cat tracking tends to cluster around the existing spots to some extent, almost as if these new spots want to occupy the same general area as the existing spots. This is quite different from the spotting on a leopard, which tends to be dispersed across the body.

The exception is the hooves. Tobianos with cat tracks often have a concentration of spots around the coronary band, often turning the hoof completely dark or nearly so.

There are spots on the legs, but typically they are not as numerous as the ones around the feet. The same is true for the face. This is the face that goes with these feet. He does have a few spots in his blaze, but they are not extensive.

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So how is this different from the Dalmatian? Well he really is a white animal with colored spots added on top. In dogs, the gene for this is usually called Ticking, but since ticking means something different in horses, I am going to use the older English term for the pattern, which is belton. This post has run really long, so I’ll split that over into a second part. And why delve into the belton pattern in dogs? Because lately there has been a handful of horses that have turned up that just might have that kind of spotting. At the very least there are horses with dark spots inside their white markings that are not tobiano cat tracking and not leopard patterning. More on those will appear in the next post!

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Partial blue eyes

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It can be really hard to get good shots of horse eyes, so I was really pleased to get a number of good shots of this Pintaloosa mare and her partially blue eyes. The placement of the blue segments certainly give her an unusual expression. This first image shows how her left eye has a blue section towards the upper front of her eye. The apparent shape is accurate – none of the bluish area is glare – since it is consistent across a number of images.

Here is her right eye, with a blue section on the lower side. Notice how a thin line wraps up along the back edge, and how uneven and inconsistent the blue area is. (The blue coloring on the left eye was uniform.)

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Here she is looking forward with her mismatched eyes, one with a blue bottom and one with a blue top.

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Here are some full-body shots of her, showing her varnish roan (leopard complex) and tobiano patterns. The varnish mark on the top of her tear bone is particularly noticeable in the first picture, and the mark across the nasal bones in the second one.

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More appaloosa face mottling

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Earlier this week I posted some examples of appaloosa facial mottling. I have a few more examples today. In each case I’ve tried to get a good full-body profile shot and then a close-up of the muzzle and, if they have any mottling, the eyes. The horse above is another chestnut varnish roan not that different from Freckles, the mare in the original post. Like her he is also in his teens.

He also has very little in the way of mottling.

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The pink areas on his muzzle are markings. To find any mottling at all, his lips have to be pulled back much like I did with the pony Thumper. Looking at this guy and at Freckles, it might be temping to assume that varnish roan appaloosas, which are appaloosas without a pattern to go with the varnish gene, aren’t inclined to mottling.  Yet this guy has an even less extensive pattern than either of the two previous varnish roans.

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I suspect that part of the reason he has such pronounced mottling is that he is probably a homozygous appaloosa. That can be hard to tell with varnish-only appaloosas, because aren’t patterned spots to remove like with a leopard or a blanket. What he does have is the extensive mottling and the pale hooves. Usually a black leg on an appaloosa has an overall dark look, but this guy has predominantly shell-colored hooves.

His mottling even includes his eyes.

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I have found that to be a lot more common in homozygous appaloosas than in heterozygous ones. Some of that may be selection, though. Appaloosa breeders have tended to prefer dark skin around the eyes, and so have selected for less mottling in general and less mottling around the yes in particular.

Yet not all heavily mottled horses are homozygous. I have somehow managed never to get a full-body shot of Dottie, even though many detail shots of her have appeared on the blog. Even without a body picture, though, it’s obvious from her hindquarters that she’s a heterozygous appaloosa. (Homozygous appaloosas do not have significant spotting.)

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Yet Dottie has a lot of mottling on her muzzle.

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I suspect that part of the reason her nose is pink is that there is a white marking there, since mottling does not usually create that much pink on one spot. Even allowing for the fact that she probably has a large snip, she still has a lot of mottling. The area around her eyes is dark, though.

This pintaloosa that appeared in an earlier post is another heterozygous appaloosa with a lot of mottling.

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Not only is it visible around his mouth and eyes, but even the area inside his ears is mottled.

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Moving back to the other extreme, here is a very loudly patterned appaloosa with almost no mottling at all. His spots say he is heterozygous, and the white area on his hindquarters (and the size of his spots) say he has the blanket pattern. He is in his twenties, so his varnish pattern – and his mottling – have probably progressed as much as they are going to go.

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Here is a close-up of his muzzle. If you look closely, he has a faint network of paler skin close to his mouth.

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And finally here is Abby. She is another varnish-only appaloosa. Like Commanche, the horse above, she was also in her twenties when this picture was taken.She is also in winter coat, so she’s slightly darker than usual.

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She does have some mottling, though it’s not nearly as pronounced as the homozygous varnish.

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As these pictures show, mottling on appaloosas covers a pretty wide range. It does not appear to be specifically linked to the presence or absence of patterns like blanket or leopard, but it does seem to be more pronounced in homozygous appaloosas. There are also probably other minor modifiers that are involved, some of which have likely been inadvertently selected in breeder’s preferences for darker skin.

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