It was a test to tweak the sensations of what it is to be and feel the reality of living as and like would an equine animal. The technician, rises up, she uses a towel to wipe her body clean of the sweat and dripping juices that permeate her stretched vaginal regions.
A few harsh and grumbling words to the man holding a long needle syringe, and she vanishes from all sight and smell.
"You did well, your mental state must be close to accepting if not wanting the change of body to remain as something permanent. Permanently keeping you as a stallion horse would help in further tests, a few might grant you some lusty minded mares to toy and try your tool." He tantalizes, offering something that you as a stallion horse and or even if an aroused male human, you would find as delightful, in many differing ways.
Decided to stay with what you are, the swaying of a big horse rump toward that monster syringe is enough to get you poked into a permanent state of arousal, erections, mating and other bestial sensations that human kind named as debauchery.