Our little lady had some trauma in her youth and was extremely resistant to being picked up and would absolutly not take direction to go into a crate. After a few years of her getting more comfortable I knew I could probably get her in again one time by tricking her, but I should save that for an emergency and nothing else. Eventually that was needed when we had to move. Of course, knowing I had to make the most of that I scheduled a vet appointment for that day.
It was somehow much worse than I had anticipated, starting as soon as I shut her in. She was so scared, throwing her full body with as much force as she could against the walls of the crate over and over and over, keeping that up while I was carrying her to the car and the first few minutes of the drive before she finally started to calm down. Watching that shook me, emotionally painful and just building anxiety about the appointment.
She actually was very submissive for the vet, who seemed to think I was crazy because at that point I was visibly a lot more terrified and upset than the cat.
Awful day in general, I have never seen an animal more depressed than she was after finishing that appointment and getting to the new place, it was horrific. She was normally extremely skittish about potentially being touched, but would invite pets sometimes. In that first day though, she was just do whatever you want I don't care. I had to pick her up body basically limp out of the crate, she had never let me pick her up. She didn't move from where I had placed her for hours, zero reaction to any action from me. She got back to her old self after a few weeks, but that day is still very painful to think back to I feel like I'm about to cry just from writing this.
I felt like I had to double up because she was already late on vaccines and it was very unlikely I'd have another opportunity soon to get her to the vet.
Knew we were moving months in advance so about six months before the move I was trying to get her comfortable going in the cage by giving her wet food in there. I thought after a couple months I would try shutting the door quietly and opening it right back up and then gradually get her used to the door being closed for longer durations, but the very first time she was very unhappy and the next couple months she basically said fuck you I'm eating the dry food in protest right in front of you when you're doing this. When she finally started going back in I felt like I can't play with getting her accustomed again, I've got to just do it on the day, and I was pretty confident that if I didn't get her vaccines then it would be a very long time.