In the summer, my horse has a very clear, though still very red, dorsal stripe. His legs are the same color as his body, and his mane and tail are a little darker, but not very noticeably. What might be causing this? Is sun factor a possibility, or is there a different gene that causes this too? I know red duns exist, though any that I've seen have noticeable darkening/striping on their legs. I'll post pics later! Posted via Mobile Device
The dorsal sounds seasonal so it's most likely countershading. Dun dorsals are crisp and noticeable. Countershading is smudgey and may fade in and out. Also dun is a dilution meaning the coat WILL be diluted usually to a peachy red on sorrels/chestnuts. Dun dorsals are also not seasonal they are on the coat year around. Posted via Mobile Device
Sorrel mare with countershading. Notice the coat is undiluted and the lack of crispness of the "dorsal". The edges sort of blend into the coat. I also know this mare personally she has no dun parents. Dun is a simple dominant meaning one parent must carry the gene to pass it, it cannot skip generations.
Here some dun dorsals dorsals they have that drawn on with a sharpe look and notice the diluted coat.
Dun dorsals can be light colored but they are still very noticeable. My dunskin's dorsal.
I think we need pictures! I wouldn't say all dunn horses are noticeably diluted, especially red dunns. I have seen a red dun who was so dark I thought she was sorrel. She's 100% red dunn, she had a grulla filly with a black sire.
Gosh darnit, it's sideways! >_<' But anyway, to clarify a few things:
LMDB, actually now that I look, his tail does seem to be darker at the top (along the line of the stripe) than around the sides. Might just be!
PBR, His stripe is quite noticeable especially in the summer, was what I meant. It is still there in the winter, just slightly less clear when the fuzzies come in. :)
Thanks for the input, everyone! I may have him color tested someday just for funzies, but here's a photo and some pedigree info: Olenas Smokin Sox Quarter Horse
I know all breed pedigree is not always 100% accurate, but it at least gives you his bloodlines. Also just curious, his papers list him as sorrel... If he did happen to be a red dun would that mean his papers were wrong? Or does AQHA not recognize color that way? Not that it matters, really, it's just all very interesting!
Now that I see pictures, I'm thinking sorrel with countershading. He didn't have a dunn parent either (ch stands for chestnut?) I'm not familiar with the site really lol! Without a dunn parent, he couldn't be dunn! :) looks like you've got a plain ole' sorrel my friend! Posted via Mobile Device
Definitely not dun. Dun doesn't just add a dorsal stripe - it is a dilution gene, which means that it has some diluting effect on the coat of the horse. Usually a dun horse is visibly different to a non-dun horse - so a red dun is visibly different to a chestnut/sorrel. The main part of the coat is usually lighter, and gets a different hue to it - some describe it as dusty, I prefer to call it a "flat" hue. The dun gene actually changes the way the pigment forms in the hair shaft, restricting it to one side, and this is why it looks lighter.
Additionally, your horse has no other "dun factor" markings. While he does have a prominent dorsal, it is caused by counter shading. It is uncommon for a dorsal that is not caused by dun to be so crisp, but not incredibly rare.
Another point is that since both his parents are chestnut, there is no way he could possibly be dun anyway. Dun is a dominant gene, which means that the horse must express the gene if they have a dun gene. This means it can't "skip generations" or anything like that.