It has been selectively bred to display in miniature the physical characteristics of a full-sized horse, and usually stands no taller than about 38 in (97 cm).

[5]: 168 [6] It appears to derive at least in part from animals brought to the USA from the United Kingdom.

[5]: 168  These may have included British and Dutch pit ponies imported in the late nineteenth century and used until the mid-twentieth century in the coal mines of the eastern and central United States, and some descendants of small horses bred in England in the first half of the twentieth century by Lady Estella Mary Hope and her sister Lady Dorothea.

[5]: 168 [11] Height is not measured to the withers, as is usual in horses, but to the root of the last hair of the mane.

[5]: 170 [11] Some colors that are rare in full-sized American horses are seen in the breed, such as bay silver dapple – light bay with white mane and tail and black legs.