Young roman slave being castrated.

The slaves were bought young, and the new owners could decide how they should be. 

If they were to work in coal mines or as a hooker, it would be better to blind them. If they were to carry heavy loads, pulling wagons, for example, sometimes it was better to burst their eardrums so they would not be startled by noises. 

If they were to work in the house of the noble families some preferred to castrate them so as not to offer risks; others, on the other hand, chose the most gifted to have fun with their cocks. What was more common was to have their tongues cut off so they would not gossip, complain, or moan. It was also expected to extend their anus so that they could be penetrated without effort.

The sellers who did the interventions often ruined the animal, crippled or killed the creatures during the amputations. 

The preparers lost many of them to bleeding or infection. But it was worth trying; the pieces were greatly valued for coming prepared.

The most essential skill for surgeons was to know for what kind of slave the creature had more talent, more vocation, or genetics. Children born from massive and robust slaves, the most stupid or revolted, were separated for the heaviest jobs, the most gifted for the red light house.

These professionals were valued, the most skillful, earned well and cared for the nobles, the citizens, and the soldiers. The most unskilled professionals cared for horses, pigs, dogs, or slaves; they made no difference.