The merle phenotype in Australian Shepherds is very similar to the coat color in Mitf mouse mutants. In addition, an emergence of an even smaller version occurred, referred to as the Toy Australian Shepherd, with adult males weighing 12–15 pounds (5.5–7 kg) and all dogs falling under a 14-inch height at the withers. Many breeders and owners of Australian Shepherds consider the Mini and Toy to be separate breeds; others consider them to be down-sized versions of the same breed. While the Mini size can be attained through selective breeding of small Australian Shepherds, the Toy size is typically a result of cross breeding with other toy breeds. ASCA and AKC consider both variants to be separate breeds.