Ass, a member of the horse family. It is smaller than the horse, standing only three to four feet (90 to 120 cm) high at the shoulder. It resembles the zebra, but the coat is not striped. A few species, however, have stripes on the legs and tail. It has long ears, a short mane, a shaggy coat, and a tufted tail. The coat varies in color from sandy or reddish to bluish gray; the belly and parts of the nose are lighter. There is usually a dark stripe down the back.

Asses were among the earliest domesticated animals. Domesticated asses are called donkeys. Their hardiness and surefootedness make them valuable pack animals. The burro, a small domestic variety, is used in the southwestern United States and in Mexico. The mule is a hybrid offspring of a male ass and female horse.

Several species of wild asses are found in central and southwestern Asia and in northern Africa. Most travel in small herds. All are threatened with extinction due to indiscriminate hunting for their meat and hides and encroachment on their grazing land by livestock.

The onager, once found in Iran, Afghanistan, and Russia, is now confined to northern Iran. The kiang, which is similar to the onager, inhabits isolated areas in Tibet. The Mongolian ass, or kulan, inhabits areas of Mongolia. The Indian ass, or khur, once ranged over northwestern India and western Pakistan. It is now found only in an area of northwestern India, and, to a limited extent, in Pakistan. The African wild ass inhabits isolated areas in Ethiopia, Somalia, and Eritrea. The donkey is descended from this species.

The onager is Equus hemionus onager; kiang, E. h. kiang; Mongolian ass, E. h. hemionus; Indian ass, E. h. khur; African wild ass, E. asinus or E. africanus; donkey, E. africanus asinus or E. asinus. All belong to the horse family, Equidae.