I had no idea what this was until I saw the momma deer.
“A piebald is an animal, usually a mammal such as a white-tailed deer or horse, that has a spotting pattern of large white and black patches. The color of a piebald’s skin underneath its coat may vary between black (under the black patches of hair) and pink (under the white patches). The coloring is generally asymmetrical, resulting in deer with abnormally wild brown and white coloration . Many animals also exhibit coloration of the irises of the eye that match the surrounding skin. This condition also occurs in white-tailed deer.
http://www.buckmanager.com/2007/07/17/piebald-deer-what-are-they/