Addax is a kind of antelope with twisted horns, and from the Hebrew, the idea of white on the hindquarters identifies it with antelopes.

Bible occurrences: Deu 14:5.

A member of the antelope family (Antilope addax) with twisted horns, probably the same as the pygarg of some versions. This word is dishon in Hebrew, and some think the word means “white on its hind quarters” which is why they think it is an antelope, gazelle, or similar species. The dorcas gazelle (Gazella dorcas) is widely distributed in Syria, Palestine, and Arabia. The Merrill’s gazelle (Gazella Merrilli) is found around the hilly country near Jerusalem, and is hard to distinguish from the dorcas gazelle.

Source: Anon-Animals