THE DUN GENE
Dun is a dominant gene that dilutes the body color of all colors but does not dilute the points. Dun is the result of the dun gene diluting a bay base coat. For example, in a bay horse, the presence of the dun gene produces a more yellowish body color with black points and primitive markings.
All duns, regardless of color will exhibit primitive markings.
There are three crosses offering the best chance of producing a dun foal. A dun mated with a dun will produce a dun 53 percent of the time, a dun bred to a grulla has a 45 percent and a dun bred to a buckskin has a 34 percent chance.

In an otherwise black horse with the dun gene, the body color would be grulla, with a mouse-gray color and primitive markings. Grulla is one of the rarest expressions of the dun gene. A grulla can have one or two copies of the dun gene. A grulla crossed with a grulla will produce a grulla 41 percent of the time and a grulla crossed with a black horse has a 28 percent change.

THE CREAM GENE
While the cream gene, which controls the concentration of pigment, influences the red family, it also affects the black family. In the black family, one copy of the cream gene dilutes a bay horse's red body color to buckskin. A buckskin is essentially a modified bay and still has dark skin and eyes.

PERLINO
A perlino, on the other hand, receives two copies of the cream gene, which dilutes both the black and red hair. Physically, a perlino appears almost identical to a cremello. The perlino's mane, tail and lower legs tend to be darker, however giving it the appearance of having darker points.

In the heterozygous form, the cream gene has little effect on black hair, which makes it possible for a black horse to carry a heterozygous cream gene and show minimal physical dilution effects. This horse might exhibit yellow-brown eyes or have a dulling of the black body color. These horses have the potential to produce dilute foals from non-dilute mates. The existence of the cream gene, however, should be apparent in the black parent's pedigree. The benefit of having a perlino or cremello in a breeding program is that Paint breeders can produce diluted coat colors a majority of the time.

Crossing a bay with a buckskin is another way to produce a buckskin foal. With this cross, there is a 30 percent chance of producing a buckskin.