The popular question today is… What is a Blue and White Horse?
Well genetically speaking, The Blue color is caused by the Dominant “Roan” gene R. While “Blue Roan” is similar to grey in that they share individual white hairs spread throughout the coat – They are two different colors, caused by two different genes! Grey is caused by the Dominant Grey gene G. In normal situations a Blue Roan, must have Black legs, Mane, tail and head! However when you infuse the coat pattern Tobiano or Overo, what is the norm is changed a bit, because Tobiano patterns horses rarely have solid legs, manes or tails. For a horse to be considered “Blue” it must have a Roan gene present and it must be Base Black (EE or Ee)!
Notes:-With very few exceptions, you will not see a Homozygous Roan. A foal born with two dominant roan genes is almost always still born or dies shortly after birth.
-Roan may occur in any base color – but the “blue” effect comes only from Base Black.
The term “Blue and White” originated in the UK to describe the “Grey and white” horses as we know them.