Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Equus (play) the owner of the stables, Harry Dalton, and Alan agrees. Dysart meets with Dalton, who tells him that he first held Alan to be a model worker, since he kept the stables immaculately clean and grooms the horses, including one named Nugget. Through Dysart's questioning, it becomes clear that Alan is erotically fixated on Nugget (or 'Equus') and secretly takes him for midnight rides, bareback and naked. Alan also envisions himself as a king, on the godhead Equus, both destroying their enemies. Dysart gives Alan a placebo "truth pill". Revealing a tryst with Jill, he begins to re-enact the event.