Equine color genetics

I told myself that the next time I got to Ireland I was going to visit John McCarthy and have a long, long talk with him. I wanted to here him talk about the Irish Draught and what it was and what he thought the future for the breed was -- just anything I could get him to talk about. Unfortunately, Mr. McCarthy died before I got to Ireland again and I've bee kicking myself ever since then. What does this have to do with color genetics you ask? Good question! Actually very little as you shall see.

The topic of Cork Arthur and his color(s) has been on my mind a good 10 to 15 years. I know a lot of other people have conjectured about what dilution genes he might or might not have. The palomino foal that I know that he sired was out of Killawalla Blondie so I was pretty sure that the cream gene came from the mare. However, there have been a number of odd colored horses by him -- buttermilk color and the like so I felt that it certainly was possible as a long shot. I got to thinking that the way I was going, Cork Arthur would be dead and gone before I got around to finding the truth out so I kicked myself into gear. I had him tested for the cream dilution and the pearl dilution but not the champagne dilution. There was no evidence at all that the Irish Draught has the champagne dilution. The new pearl dilution was a possibility since the origins of the ID include the Spanish breeds. I did not test him for dun zygosity because you need hair from one or both parents and I was relatively sure that he only had one dun gene.

I obtained hair from Cork Arthur and sent it to the UC Davis Veterinary Genetics Laboratory for testing. Here we go...

Cork Arthur is:

Red factor e/e - Only the red factor detected. Basic color is sorrel or chestnut in the absence of other modifying genes

Agouti A/A - Black pigment distributed in points pattern. Basic color is bay or brown in the absence of other modifying genes

Cream dilution N/N - No evidence for the Cream dilution altered sequence detected. Basic color is sorrel or chestnut, bay or black in the absence of other modifying genes

Pearl dilution N/N - No evidence of altered sequence detected


So we all know now. That subject can be put to rest now.