Almost unheard of in its true form today.
Proud cut is where the vet screws up and doesn't cut out all the testicular and epididymus tissue from the horse, and the horse continues to produce a high level of androgens because of it.
I haven't read about any "TRUE" proud cut
Many people call a gelding who mounts mares and still has stud tendancies as "proud cut". They are wrong. Because the actions are learned and some of it is natural anyways, like mounting for dominance....
Some people call the aggression in the herd proud cut when it is just plain pecking order.
People who don't like the gelding use the term Proud cut to make an excuse for the horse or have the horse removed from the pasture.
Course I found it funny when one horse was deemed proud cut by the barn manager, told the owner they must move the horse and either have him regelding to fix him, or he can't go back out.
Owner gave her a funny look. BM made a HUGE mistake that cost her job, because one, the lady was best friends with the owners, and two, the horse she was demanding be removed because "HE" Was proud cut was really a mare who was just dominant out there.
Which is why I look before I speak. LOL
Anyways, Because vets use different techniques now to remove the testicals, the chances of a TRUE proud cut is practically zero.
Now, when I hear it, I roll my eyes and think "Ignorance" as I walk away.
Because people use the term ALL Wrong....just to make an excuse for something that is just NATURAL and won't go away.