Ileocolonic aganglionosis in an overo foal

Abstract

The American paint horse or pinto (Spanish for painted) has two different types within the breed: the overo, which has white patches on a dark coat and the tobiano, which has black patches on a white coat. Within the overo type the amount of white may be quite small or a horse may be almost entirely white, but the basic pattern is that the ventral abdomen is spotted white whilst dorsal aspects are dark. The overo is considered to be recessive.