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
In the real world, antelope is a broad term to refer to those bovids which are not cattle, sheep, buffalo, bison, or goats. There are 91 types of antelope, but the DWU has largely refrained from specifying any of them. However illustrations with K9 and the Missing Planet and Jungle of Doom do rule out scores of species in the family.