Splashed white 2/deafness (SW2)
The splashed white 2 (SW2) gene causes white markings. They can range from minor facial markings and socks to the white face, blue eyes, white legs and white belly of a typical boldly marked splash horse. It is rare but possible for SW2 horses to be deaf.
Chestnut splashed white horses generally have larger markings than bay/brown or black splashed white horses.
The SW2 version of splashed white is only found horses descended from a Quarter Horse mare called Katie Gun, born in 1987 in the USA.
It is possible (though very rare) for horses to carry two copies of SW2.
Gene or region and technical reference
Gene: PAX3 (causative). Reference: Hauswirth et al. (2012)
n. Test developed using manufactured DNA, animal controls.
SW2. Test developed using manufactured DNA, animal cases.
This black SW2 stallion is Bremerpark Shadow Gunner (Frankie). Many thanks to Five Mile Stud for sharing this picture of their handsome boy.