Archive | Skin pigmentation

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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Mottling on non-greys

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In the comments section of the previous post, Jo-Ann Ferre mentioned mottling on non-greys, which is also unrelated to appaloosa patterning. That reminded me of one of the pictures in the upcoming book, of the early 20th century Percheron stallion Keror. He was a prize winner in his day, despite the extensive loss of pigment on his face. I’ve seen this on a wide variety of breeds, but whatever the cause it does not seem to run in families or be passed along to offspring. Perhaps that is why breeders have been willing to use stallions like this in years past.

I also apologize for the delay in posts and in replies to private questions. I am slogging through what I hope are the last revisions to the book, so that is consuming the lion’s share of my attention. I should be back to more regular posting in a few days.

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A different kind of mottling

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I took some pictures at a local fun show this past weekend, and several are relevant to the topic of cryptic appaloosas like Thumper.

In the previous post I mentioned that the mottling on Thumper’s lips was what alerted me to the fact that he was not an ordinary roan. I wanted to clarify that it was the mottling paired with other clues (like his striped feet) that convinced me he was a varnish roan. Mottling on the mouth alone is not an absolute sign of the appaloosa gene. This mare has mottling, too, but she’s not an appaloosa.

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She’s a fleabitten grey Arabian mare. Obviously her mottling did not come from varnish roan, since Arabians do not have the necessary gene for that.

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Her mouth is mottled because she is a grey. It is not an uncommon trait among greys. In some cases, like this mare, it is pretty subtle. In this picture, taken in the shade and with front of her mouth hidden from view, her skin looks uniformly dark.  Often mottling on greys is not visible in pictures. Sometimes it is nothing more than fine pink speckles around the edges of the white markings.  On others it is very pronounced and involves large areas of pink skin.

This is one reason why it would be easy to hide varnish roan in a predominantly grey breed. While mottling on the mouth is usually a red flag that the appaloosa patterns might be involved, it can seem pretty routine to breeders with grey horses.

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