For many years the controversy has raged over the existence (and acceptance) of "parti-colored" Arabians, both in the hobby and in the real horse world. Particolors, at least in terms of horses with white on the body in varying amounts, do exist in purebred Arabians, and by all indications were an original part of the desertbred horse. According to Michael Bowling, a noted authority on the breed, "most of those who express any opinion on excessive white seem to view it as the hallmark of the ancient 'hot-blooded' gene pool." Others taking similar positions included Gladys Brown Edwards and Carol Mulder. Ancient texts and even Arabic mythology contain references to spotted purebreds; one text went so far as to outline thirteen varieties of spotting found in the breed!
Unfortunately, in an effort to distance itself from the spotted circus horses of the day (often called 'Arabians' to seem exotic), the Registry chose to include a phrase in the breed standard regarding the undesirability of white markings on the body. The phrase was removed from the AHSA rulebook in 1975. There is currently no official sanction for prejudice against excessive white for either registration or showing purposes.
The kind of spotting found in Arabians is usually a type of sabino, and is most often genetically linked to the color chestnut. Although sabino is normally dominant, in Arabians it can behave like a recessive -- hiding for many generations -- if the chestnut color is not inherited. In these cases, the bay or grey offspring of a given cross might be quite moderately marked, but a chestnut foal might display the flashy white of a distant ancestor. In general, sabino Arabians are not extravagantly marked compared to Tennessee Walkers or Clydesdales, because they are rarely bred to other sabinos. Given the long-standing prejudice against them, they are more likely to be bred to more conservatively marked mates. Breeding sabino x sabino usually leads to progressively more white on the offspring.