Wild bay, also called light bay, is a shade of bay. As all bay coloured horses, wild bays have a reddish coat with black points (mane, tail, lower legs and ear tips). However, wild bay distinguishes itself from normal bay as the black on the lower legs doesn't reach up unto the knees.
It is not yet known whether this colour has a unique genetic base, or is caused by other factors. It is currently seen as a version caused by agouti, but it may be part of something different too.
Wild bay is often abbreviated as A+ (or AA+), where the '+' stands for 'wild type' and the 'A' refers to the agouti gene. The wild-type stands for being an original colour in the horse, though this is only a theory based upon the little amount of black often seen in bay dun horses, the original horse coat colour.
In the game wild bay is very rare and only exists in a few breeds. Its genetic cause is an agouti allele, A+, which is dominant over all other agouti alleles (bay, seal brown, black).