A model animal causing the white hair development as anon-human mammalian animal with a phenotype such that the colorof the hair first growing after birth is black or almost blackand the model animal then causes the spontaneous white hairdevelopment following aging, where (1) the activated RET geneis genetically inserted in a hetero form and (2) the endothelinreceptor B (Ednrb) gene is deficient in a hetero form, or theEdnrb gene is deficient in the homo form or in a hetero formand the Ednrb gene is genetically inserted in the homo formor in a hetero form under the DbH promoter.In accordance with the invention, there is provided amodel animal causing the white hair development, which is themost suitable for research works about the mechanism of thewhite hair development and research works about apharmaceutical preparation or a treatment capable ofpreventing the white hair development.
