Splashed white 1 is an incomplete dominant white pattern that gives the horse the resemblance of being dipped into a bucket of white paint. Horses usually stand out with a bald face and four white legs, though it has been found the mutation can be expressed in something as little as a white foot or a snip.
This pattern must be ancient as it appears in many diverse breeds, ranging from the Icelandic horse to the American stock horses. It is incomplete dominant and can hide as a simple blaze (usually bottom heavy) and a white foot. But when a horse receives one allele from either parent, the combined effect can be striking to say the least. Due to this illusive behavour of hiding for generations and suddenly appearing in extremely loud patterns, it has eluded breeders for a very long time.
Splashed white 1 is part of the splash group that often contains horses with broad or distinct white patterns that appear to be different from the sabino phenotype that usually has loose white hairs around the edges. It is important though to realise this categorising of white patterns (as well as naming them) is based upon sometimes minute differences, and it is therefore not at all unthinkable they sometimes overlap.
In 2012, and again in 2013, several mutations responsible for splash patterns have been identified by scientists. The most famous one, the here mentioned splashed white 1, was found on the MITF gene. Since the DNA test became worldwide available, it has only just become clear how well this pattern can hide in plain sight.