Dholes were creatures native to a world or worlds several thousand light-years from Earth. They were blue, worm-like, and about twice the size of an adult human. They possessed large, sharp teeth and no eyes.
During the Cretaceous period, alien colonists unwittingly carried a group of dholes to Earth. The Seventh Doctor arrived to pick up Ace, and while looking for her he fell into a pit of dholes, narrowly escaping from them. (PROSE: Living in the Past)