Coat: The Labrador Retriever's coat should be short and dense, but not wiry. The coat is water-resistant, so the dog does not get cold when taking to water in the winter. That means that the dog naturally has a slightly dry, oily coat. The genes known about previously have had their number increased by the introduction of the K locus, where the dominant 'black' allele KB is now known to reside. Black or chocolate Labradors therefore must have the KB allele. Yellow Labradors are determined at the E locus, so the K locus is irrelevant in determining their colour. Variations in numerous other genes control the subtler details of the coat's colouration, which in yellow Labradors varies from white to light gold to a fox red.