What is a "homo" stallion?

With California Chrome winning the Kentucky derby, people are wondering what it is when a horse has “chrome”. California Chrome has great “chrome”, a chestnut stallion with four white legs and a white emblazoned forehead.

California Chrome

A great example of a horse with lots of chrome is or Arabian Stallion Tha Dude, a black stallion with four white stockings and a white blaze on his forehead:

Tha Dude

Tha Dude has a great pedigree and he is is at stud in 2014, and it is hoped that his babies are homozygous for black color (Homo), meaning that he will only sire black horses. We are hoping that Dude is homo:

Tha Dude may be homo