A piebal is an animal, especially a horse, that has a spotting pattern of large white and black patches. The colour of the horse's skin underneath its coat is both black (under the black patches of hair) and pink (under the white patches). This alternating colour pattern is irregular and asymmetrical. Other than colour, it is similar in appearance to the skewbald pattern. Some animals also exhibit colouration of the irises of the eye that match the surrounding skin (blue eyes for pink skin, brown for dark). The underlying genetic cause is related to a condition known as leucism.