We used to trap hogs regularly on some property I owned a few years ago. Most of them we either gave away or had made into sausage. The really small ones we gave to a guy who does the "racing pigs" thing at local fairs. Once though we kept an 80 or so pounder to try to fatten him up. After a while, we named him Wilbur. He never would fatten up though. He only ate enough to stay alive. After several weeks, my wife told me we had to set Wilbur free. My co-trapper said that we should castrate him first so that he would get larger and be less gamey if we ever caught him again. So, one day I go to Wilber and tell him that I have some good news and some bad news.
After the cutting, poor Wilbur just hunkered down in a corner of the pen and refused to budge. We finally got him out and he hauled azz for the tree line. He never came back as far as we could tell but a couple of years later we heard that someone in the area killed a huge castrated hog. Poor Wilbur, RIP.