A dapple grey horse has intermediate greying of its coat, with patches of grey hairs mixed with the original color. The dapple grey stage of greying generally occurs between four and 12 years old.
As horses age, their natural coat color is gradually replaced by white hairs. Intermediate stages in the greying process include rose grey, salt and pepper grey as well as dapple grey. Eventually, the greying process results in a white horse or a flea-bitten grey horse.
The grey gene is an autosomal dominant gene and does not skip generations. If a horse has even one copy of the grey allele, then it will always become grey. Dapple grey horses do not keep their speckled patterns and end up greying further. Dapple grey horses are part-way through the greying process while rose grey horses and salt and pepper grey horses are in the early stages.
Horses at the end of the greying process appear white. However, these horses are not true white horses. True white horses are genetically white in color, not due to the greying process. The true white horses have pink skin while the grey horses have dark skin and eyes. Flea-bitten grey horses are white with darker flecks throughout their coats.