Splashed white

The white head, tail, and lower portions of this foal are typical of splashed white.

Splashed white or splash is a horse coat color pattern that produces pink-skinned, white markings. Many splashed whites have very modest markings, while others have the distinctive "dipped in white paint" pattern. Blue eyes are a hallmark of the pattern, and splash may account for otherwise "solid" blue-eyed horses. Splashed white occurs in a variety of geographically divergent breeds, from Morgans in North America to Kathiawari horses in India. The splashed white pattern is also associated with congenital deafness, though most splashed whites have normal hearing.

Characteristics

The splashed white pattern is characterized by blue eyes and the appearance of having been dipped, feet-first, into white paint. The margins of the white markings are crisp, smooth, blocky, and well-defined. The head and legs are white, and the tail is often white or white-tipped. The underside of the body is white, and a connected white patch often spreads smoothly up either side of the thorax. On its own, the splashed white pattern is seldom responsible for white markings that reach the topline, and so it has been categorized as "overo" by Paint horse and Pinto horse registries. As sabino-type markings also originate on the underside, some splashed whites can be mistaken for cleanly-marked sabinos. Both patterns can be present on the same horse, but splashed white markings are crisp and blocky, and horizontally-distributed. In particular, the face markings of splashed whites are straight-edged and bottom heavy, whereas those of sabinos are often tapering or feathered. The presence of additional white patterning genes can intensify the amount or obscure the characteristics of splashed white markings. Notably, the ears are seldom white.

Minimal splashed whites

Breed societies for which minimum or maximum white markings are a factor in registration have created imaginary lines to simplify the selection process:

These splashed white Thoroughbreds have mask-like white faces, blue eyes, and dark-colored spots on their lips.

• From the ear, to the eye, to the corner of the mouth, to the chin groove,
• the knee on the foreleg, and
• the hock on the hindleg.

White markings extending past these lines are considered "pinto", "paint" or "colored" while white markings which do not cross these lines are not considered to suggest these traits. However, horses without "excessive white markings" can still have the potential to produce pinto offspring. Splashed white horses are especially well-known for producing generations "solid-like" horses, followed by an errant, classically-marked splashed white. Discretely-marked splashed whites are responsible for some families of cropout American Quarter Horses and Appaloosas.

The most minimal expression of the splashed white pattern can include just a snip and/or star and/or hind coronets. Some suspected splashed whites have had no white markings at all! When only minimal markings are present, a few qualities can belie splashed white. Stars and snips may lopsided, off-center, or otherwise strangely placed. Blazes are usually blocky or straight-edged, and bottom-heavy; in contrast, sabino blazes are often hourglass-shaped or tapering with feathery or jagged edges. Splashed white blazes may also be crooked or skewed to one side. Sabinos with a bold blaze almost invariably have white on the lip or chin, and this is not the case for the facial white of a minimally-marked splash; the upper lip often remains colored.

Leg markings in a minimally-marked splashed white range from hind coronets to high-whites on all four, or marked hindlegs and unmarked forelegs. While sabino leg markings are often tapering with distal patches, the leg markings on a splashed white are crisp but "straight across" or blunt.

The most reliable identifier of the splashed white pattern is one or more blue, or parti-colored eyes. Splash is a strong candidate especially if blue eyes run in a family without a history of the frame pattern.

Inheritance

This mare has a white tail and a large, connected area of white across the lower part of her body. The jagged edges are due to sabino traits.

The gene responsible for the splashed white pattern is not known and has not been mapped, however studies suggest that it is not part of the linkage group that includes roan and tobiano. The KIT gene is not thought to be a candidate gene for splashed white. Preliminary studies from the early part of the 20th century suggested that splashed white was the result of a recessive gene, however this is no longer believed to be the case. It is more likely that many splashed whites go unidentified, whether because their markings are too minimal to register as "pinto" with breeders, confusion with sabino, or the confounding effect of multiple white spotting patterns. These effects also likely account for the apparent lack of homozygous splashed whites, as suspected homozygotes would still produce unremarkably-marked offspring. It seems therefore more likely that splashed white is the result of an incomplete dominant gene, with homozygotes exhibiting the characteristic splashed white phenotype. Just as the presence of additional white patterning genes can increase the amount of white, other genes may be responsible for restricting the expression of splash.

Health concerns

This pony's face markings and blue give him away as having both splash and tobiano patterns.

Some horses with the splashed white pattern have been shown to have congenital deafness, though many or most have normal hearing. This type of deafness is probably similar to instances of deafness in white or piebald, blue-eyed examples in other species. In white-coated cats and dogs with deafness, an absence of melanocytes in the inner ear leads to death of the hair cells, which are necessary for perceiving sound. The presence of pigment around the outside of the ears - which almost all splash horses have - does not indicate a presence of that necessary pigment in the inner ear. Domestic horses often cope well with deafness, and deaf horses may go undiagnosed. Some deaf horses are more skittish than normal, while others are distinctly calmer. Deafness in horses can be diagnosed by brainstem auditory evoked potential (BAEP), which is minimally invasive and requires no sedation and minimal restraint. While blue eyes and a white face are often associated with deafness in other species, apron-faced, non-splash horses are not known to be deaf. Nor is the presence of one blue, one normal eye indicative of unilateral deafness. The case horse in Hardland's 2006 case study had one blue eye, while the other was parti-colored, but the horse was bilaterally deaf.

Prevalence

The splashed white pattern was first identified in Finnish Drafts and Welsh ponies by Klemola in 1933. Originally believed to be very rare outside of Europe, splash is turning out to be more common than previously thought. The apparent spike in "new" splashed whites may be due to the pattern's tendency to masquerade as modest markings. Since the original study in the early part of the last century, splashed white has been identified in Icelandics and Paints, Miniature horses, American Saddlebreds and Morgan horses, as well as in the Irish Tinker or Gypsy horse, the Indian Kathiawari and feral Abaco Barbs of the Bahamas. Minimally-marked splashed whites have been responsible for cropouts among American Quarter Horses and Appaloosas.