Bay or bay dun?

[Rocket's mom]

I need help from some of you color experts out there. I have a colt that I'm going to register and I thought he was a bay. Now I'm beginning to doubt my color choice. He has a very prominent dorsal stripe that runs down his back and down through his tail. Is he a bay or a bay dun? Do all bays have dorsal stripes or not? Thanks for any help you all can give me!

 

[love_casper]

Not all bays have dorsal stripes, but all duns must have dorsal stripes.

Depending on what the rest of him looked like... does he have other characteristics such as shoulder bars or leg barring... he could be a dun. But most of mini foals have countershading, which is just a random dorsal stripe on foal coats, and it eventually goes away.

Duns MUST have one dun parent, as it's a dominant gene and cannot hide. Also, dun is still technically a dilution gene, and on bays typically it will leave the head/legs normal bay color but the rest of the body will be slightly lighter, save the stripe of course.

Would be easier to tell with a pic, but hopefully you'll be able to draw a conclusion based on the above.

 

[GypsyMoonMinis]

There is some debate now on if its a dilution or a modifier like agouti, since it adds the primitive markings. A bay dun would have points that are lighter than black, but could be dark enough to be mistaken. And dun always adds primitive markings.

http://www.dungenes.org/4_basic_dun_colors.htm

http://www.grullosbysk.com/dun.html

 

[albahurst]

I have been in recent contact with the UC Davis genetics lab regarding duns. According to them, a dorsal stripe 'doesn't really matter' to identifying a true dun. There are other reasons for dorsal stripes. So, the only way to really know for sure if your horse is a dun is to have him tested, IMO.