Overo refers to a pinto coloration pattern of white over dark body markings in horses. There are at least three different genes which fall under the "overo" classification: frame overo, sabino, and splash overo. Overos often have fully blue or partially blue eyes. To complicate matters further, some of the spotting gene patterns can be combined to produce a horse with multiple color traits. The genetics of overo and related patterns are still being researched and are not fully understood. The fr… (More on Overo)