I would agree with Chiilaa here. I haven't seen dominant white on horses other than completely white, but it doesn't look like any pinto pattern I've seen and it doesn't really match up with any leopard pattern either.
I am actually getting more of a tobiano/sabino/splash feel more than DW.
MelissaAnn, can you tell us what breed he is? And what his breeding is if possible?
He is a missouri foxtrotter. The ad did not mention his parents or even his special color. Because Chilla brought up dominate white, I googled it, and was told the Sabino1 allele has been found in foxtrotters, while DW did not mention foxtrotters. But who knows, he could be a mix of many things, craigslist is full of unreliable people.
Sabino, roan, dominant white and tobiano are all mutations of the same chromosome. They are all KIT mutations, and KIT loves to mutate more. Currently there are at least 2 different types of sabino, and 12 types of DW thought to exist, with tests available for sabino 1, and 5 strains of DW.