Equinoid

Equinoids were a race of humanoid horses.

Biology
Equinoids resembled purple horses with yellow spots. Unlike horses, they stood on their hind legs and had humanoid hands with four fingers and a thumb. (COMIC: Perceptions)

History
In the 19th century, two Equinoids, husband and wife P'fer'd and M'rek'd, crash-landed on Earth after running out of fuel. After setting off a distress beacon, they disguise their ship as a solicitor's office, Binns, Beech & Evans Solicitors, using a Mark III Image Inducer, so as to stay inconspicuous in Victorian era London. The Eighth Doctor used spare energy cells from his TARDIS to send them home again. (COMIC: Perceptions)

The people of Cicero Prime rode robotic Equinoids and raced them in the Battle of the Equinoids. The nobility placed bets on which rider would win. (AUDIO: Kingdom of Lies)

Behind the scenes
A matching description for the Equinoid was made by the Third Doctor in TV: Frontier in Space when listing the species attending the Third Intergalactic Peace Conference, but it is currently unknown if they are the same species.