Breyer has announced the winners of their most recent Connoisseur model, which is a beautiful homozygous bay tobiano decorated by Summer Prosser.  This variant of the Rejoice model (first created by Summer Prosser in 1998) features some really impressive colorwork.

In Breyer's words, Pandora "has finely detailed ink spots and mapping, plus striped hooves and ermine spots."  With a description like that, I have to think that Breyer is teaching a new generation of collectors more about genetics and horse coat color than I ever could have imagined!

Let's start with "homozygous bay tobiano."  A tobiano is a pinto horse where the white markings are vertical, and cross the spine.  Most tobianos also have white legs from the hocks or knees down, a dark neck, and normal markings on the face (stars, snips, etc.)

Bay, as you probably know, is one of the three horse coat colors.  All other horse coat colors come from genetic modifications to the three basic colors: bay, black, and chestnut (or sorrel).  A bay horse has a brown body with black points - legs, tail, mane, and ear tips.  

If a tobiano has white legs, how do you know it's a bay?  Mainly through its genetics.  If you know the colors of the animals in the horse's pedigree, and you have some genetic tables at hand, you can calculate whether the horse in question is genetically a bay.

From a practical standpoint, the "bay" in "bay tobiano" is often physically expressed through a black mane and tail, in addition to a brown body with large white markings.  This is why bay tobianos are often called "tri-color," since they have three colors showing - black, brown, and white.  And this is what we see with Pandora - in addition to his ermine spots, he has black in his mane and tail.

"Homozygous" takes us into more technical territory.  Suffice it to say that the genetics of horse coat colors are a little complicated.  You are probably already familiar with the layman's terms "dominant" and "recessive."  For example, in people, blue eyes are a recessive trait, while brown eyes are a dominant trait.  If a man with blue eyes and a woman with brown eyes have a child, that child will have brown eyes.

The technical terms are really homozygous (dominant) and heterozygous (recessive).  

A homozygous bay tobiano, then, is one who carries the dominant genes for both bay and tobiano.  Pandora, as a homozygous bay tobiano, will always produce foals which are bay tobianos.  Regardless of the color of their dam.

Being able to track the genetics down to say that "this is a homozygous bay tobiano" is also a sure-fire way to ensure that the horse is, indeed, bay.  As we noticed with Pandora, he has white legs and only small amounts of black in his mane and tail.  You could question whether or not he's even a bay - but knowing that he's homozygous for both bay and tobiano is a definitive answer.