Join Date: Aug 2010
Location: Perth, Western Australia
• Horses: 0
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.
Mods, grant me the serenity to see the opinions I cannot change, courage to change the ones that should change, and the wisdom to spot the trolls.