The Leopard spotted horse is one that catches that attention of horse people and non-horse people alike. However, it has taken some time for the genes responsible for the coat to be genetically discovered. This is in part due to there being multiple genes at work: the LP Complex and Pattern genes. The LP Complex puts white hairs onto the horse’s coat, this is called Varnish Roan generally when no Pattern genes are present. Pattern genes rearrange the white hairs put onto the horse’s coat into different patterns. Note that some horses still do varnish out even when Pattern genes are present.
As the geneticists were in the process of discovering PATN 1 genetically it was theorized that PATN 1 resulted in Leopard and Few Spots coats. The theory was that a horse heterozygous for the LP Complex and for the PATN 1 gene the horse would be a Near Leopard. A horse heterozygous for the LP Complex however homozygous for PATN 1 the horse would be a Nose to Toes Leopard. A horse homozygous for LP Complex with the PATN 1 gene present will result in a Few Spots coat.
In March 2015 the PATN 1 test was announced as being available to the public for DNA testing. This is a very exciting test for colour enthusiast and breeders alike. UC Davis offers the PATN 1 test, which can be found here, for only $25 USD alone or a package deal for the LP Complex plus the PATN 1 test for only $40 USD. Breeders striving for the Leopard spotted coats can have their breeding programs greatly benefited by DNA testing for the PATN 1 test. Colour enthusiasts can enjoy PATN 1 testing to help see what breeds the PATN 1 gene may be found in by testing their non-PATN 1 horses. With many people testing, we may be able to find PATN 1 present in unexpected breeds, hidden without the LP Complex to bring it to light.
As more people are DNA testing their horses for PATN 1, it is becoming apparent that the previous theory of LP Complex + PATN 1 is not completely true. Horses that are testing heterozygous and homozygous for PATN 1 are not always appearing to be Near Leopard or Nose to Toes Leopard horses. This is showing that there are still other factors involved when it comes to breeding Leopard spotted coats. The LP Complex coats are staying true to their name and are proving to be very complicated.