Black coat color in Pembroke Welsh Corgis is caused by a recessive gene called K. Dogs with two copies (KK) are black, while carriers (Kk) are red or sable. Dogs without the gene (kk) are fawn.
Black corgis result from selective breeding and are relatively rare, making up about 5% of the population. There is no evidence that black corgis are less healthy than other colors, though some studies suggest black dogs may be more prone to certain skin conditions.