“Proud Cut”

Even after gelding, some horses still act like stallions-herding or even mounting mares, charging “rival” geldings, showing reluctance to separate from mares, and so on. Traditionally, these geldings are referred to as “proud cut”. It has been claimed that this was because the veterinarian had neglected to remove all of the testicular tissue. More likely, the behavior is due to overactive adrenal glands, which also produce testosterone.