The colour is often seen in all breeds, and one breed (Cleveland Bay horses) are exclusively bay.
There are different terms to describe the shades of bay, however these vary depending on where in the world they origionate, the most common are as follows:
- Blood Bay
- Red Bay
- Golden Bay
- Light Bay
However the shade is generally based on wether the horses base coat is more of a blackish, reddish or yellowish tone.
There are many proposed theories for a bay horses coat, but most agree that the basic genes are
EE or Ee (which makes the horse black) and the dominant gene AA or Aa - Agouti (which makes the black restricted to the points). Agouti is stronger than the black gene, and as such even one dominant gene (Aa) Will make the black stay to the points.
Bay is a stub.