During the Y2k scare, my family (mostly mom) became very involved in "prepping" for a time when we might have no power, no way to buy food, etc. As part of the preparation, we purchased chickens and rabbits so there would be a supply of meat. It turned out that I was the only person in the neighborhood who was cold-hearted enough to kill anything, and a few families in our local homeschooling community would occasionally ask me to come butcher something for them.
One family operated a farm. They had good intentions but things were out of hand, and often there was serious neglect. Sometimes they would ask me to come over and butcher inedible rabbits just to put them out of their misery. At the time I thought that I was just helping, but now I wonder if I was cooperating in neglect? I didn't report anything, I figured that the family didn't need more trouble. (I saw this farm a couple of years ago, and the management had improved significantly. There doesn't seem to be the danger of severe neglect anymore.)
I was thinking of mentioning it in Confession anyway just in case, but I wasn't sure if it was really sinful, and, if so, to what degree. Has anyone else experienced this (veterinarians, maybe), and how would you have handled it?