Q: Why are grey horses born darker?
A: Compared to white horses with pink skin, greys possess a modifying gene inherited from one or both parents. This gene causes the horse’s coat to turn grey with age even though he was born darker, usually chestnut or bay. The skin of grey horses is not pink and will stay the same colour from birth (usually black).
The modifying gene affects the hair follicles’ ability to produce melanin that gives the coat its colour; hence, over time, as new hair grows, colour will appear to be lost. This can often be most apparent at the change of season when a new coat is grown.
The speed at which a horse goes grey varies between individuals, but in foals and yearlings, the first white hairs usually appear around the muzzle and eyes and on the flanks. Over time, his coat is likely to become dappled and eventually turn completely white, perhaps with flea-bitten markings.