The heritability of blue eyes in Spanish horses

Horses with white faces often have white eyelashes and blue eyes due to the ‘splashed gene’. In the US, testing by means of DNA allows breeders to select for genetic traits in horses, such as blue eyes

- Dr Mac.

In the US, testing of horses has moved from being an academic discipline published in scientific journals to commercially linked research enabling owners and breeders to DNA test for coat colour, conformation and performance genes. An interesting recent finding is the heritability of blue eyes in Spanish horses. Blue eyes are linked to the so-called splashed gene, which is mostly found in horses with white faces, long white stockings and white hooves.

In certain breeds, such as the Pura Raza Española horses (purebred Spanish horses), some breeders have selected for blue eyes, white faces and long white stockings. Commercial DNA testing of horses’ hair samples has recently identified two new genetic variants of the splashed gene that are directly responsible for horses with blue eyes.