The Hounds were an elite Angiran military organization loyal to the emperor of Angira.
History and specifics
In the 23rd century, Hounds soldiers served in battle for at least two emperors. One noted engagement occurred in the settlement of Agra, and was followed by a memorable celebration involving much food and drink.
Circa 2236, the Hounds were disbanded.
In 2266, six former members of the Hounds were present in the Angiran palace during a coup d'état. When he saw them, Prince Vikram recalled their service in Agra and spoke highly of them. All six gave their lives to help Vikram, Hikaru Sulu and Spock escape from the palace. (TOS novel: Shadow Lord)