Antelope

Antelope were Earth ruminants which K9 once encountered on a planet in another dimension partially inhabited by ex-Tellac miners. They lived in herds alongside other Earth animals from widely varying periods of evolutionary history. (AK9: K9 and the Missing Planet)

The Second Doctor and Jamie once used a herd of animals — which included s — to stampede a group of Quarks. (TVC: Jungle of Doom)

Behind the scenes
As far as the DWU is concerned, antelope have been portrayed as a unique species. In reality though, antelope is a blanket term to refer to those which are not cattle, sheep, buffalo, bison, or goats. The exact species is not specified in either of the antelopes' appearances.