Splash (SW), also known as splash white or splash overo, is a pinto pattern. Heterozygous splashes appear to have normal white markings and in some rarer cases no markings at all. When the pony has another pinto pattern heterozygous splash markings can appear to blend in or it can increase the amount of white. Homozygous splashes have a distinct look to them and look like the pony was dipped feet first in white. In the absence of testing the appearance of a distinctive homozygous splash is used to confirm the existence of splash.
Splashes frequently have one or two blue eyes. Homozygous splashes almost always have blue eyes. Heterozygous splashes often only have one, a partial, or do not have them at all. Splash is the default source of blue eyes in (non double dilute) Chincoteagues. No independent blue eyed gene has been identified in horses.
There is a test available for five versions of splash. SW1 is common and widespread and is likely the version that exists in Chincoteagues based on its behavior and appearance in the breed. The SW1 mutation is located on the MITF gene. The other four versions are less common and are from specific breeds and bloodlines. There are likely other version of splash that have not yet been found as obviously splash appearing horses have tested negative for the five known versions.
SW2 is the Colonels Smokingun line of Quarter Horses & Paints which appears to originate from his dam Katie Gun. It is believed to be a homozygous lethal. The SW2 mutation is located on the PAX3 gene.
SW3 is the TD Kid line of Paints. It appears to cause problems in its homozygous state. The SW3 mutation is located on the MITF gene.
SW4 originated with a Freiberger gelding who had no offspring. The SW4 mutation was located on the MITF gene.
SW5 is from a line of Appaloosas and only produces minimal white. The SW5 mutation is located on the PAX3 gene.
There is a link between splash and congenital deafness, however most splashes are not deaf. The frequency of deafness in splashes has not yet been studied.
The first known photographic evidence of obvious splashes is from the 1960/1970's. It is likely that splash was introduced into Chincoteagues during the outcrossing that brought in tobiano. Splash is found in both the Virginia and Maryland feral herds. Numerous Misty family ponies show minimal expressions of splash and Misty may have had splash based on her skewed blaze.
Black silver heterozygous splash. Splash expression is limited to four white feet, blaze and lips, and one blue eye. Surfer Dude, 2007 & 2010, Picture by Amanda Geci.
Chestnut homozygous splash and bay tobiano+ heterozygous splash. Foal was born in 2001 and was sired by Surfer Dude out of Island Breeze. Foal had a similarly marked full sibling in 2002, below. 2001 Filly, Picture by Amanda Geci.
Chestnut homozygous splash. Foal was born in 2002 and was sired by Surfer Dude out of Island Breeze. Foal had a similarly marked full sibling in 2001, above. Sea Breeze Blue, Picture from Teager, Life on Chincoteague & Assateague Islands by Charles N Showard and Kevin N. Moore.
Chestnut homozygous splash and chestnut tobiano+heterozygous splash dam. Sired by Surfer Dude. Surfer's Rouge Wave and Thetis, 2010. Picture by Amanda Geci.
Black silver heterozygous splash as a 2 year old and as a 5 year old. Son of Surfer Dude, full sibling to Soul Surfer. Surfer Dude's Riptide, 2011 and 2014, Picture by Amanda Geci.
Splash with one blue eye. Note her dipped in paint appearance. Daughter of Surfer Dude. Surfer Girl, Picture courtesy of Kim Porter.
Chestnut heterozygous splash with blue eyes. Son of Surfer Dude, full sibling to Surfer Dude's Riptide. Soul Surfer, 2014, Picture by Amanda Geci.
Chestnut minimal splash with a blue eye. Diamond's Jewel, Picture by Amanda Geci.
Black silver splash. Son of Surfer Dude. Phantom of the Waves, 2014, Picture by Amanda Geci.
Chestnut minimal splash foal with a blue eye. Note the skewed blaze. Maddox, Picture by Amanda Geci.
Flaxen chestnut splash from the Maryland herd. Photos from postcards.
Solid bay heterozygous splash with blue eyes. Feral filly, 1996, Picture by Amanda Geci.
A likely homozygous splash mare with her heterozygous splash foal. Historical reference. Feral mare and foal, 1977, Picture by Joseph Spies from Wild Ponies of Chincoteague.
Chestnut splash foal. Historical reference. Feral mare and foal, 1970s/1980s, Picture from an old postcard.
Bay homozygous splash. Historical reference. Feral pony, 1967, Screen shot from a Wild Kingdom episode.