My 25 pound cat, Orville, was more than a handful when he flipped his lid. If he went to the vet and spent more than a couple of minutes inside, he would start to lose it. To even get to that point, we had to stop using the carrier while driving as if we did, he would be screaming in rage before we walked inside. We started taking him in a pillowcase with just his head sticking out, and we could at least get inside before he went off the deep end. I have a lot of scars on my hands and arms from Orville, and almost all of them are from taking him to the vet. He was at one time, "The worst patient ever" at the vet I used to go to. There's a new one now, not as big as Orville, but even more insane. He was pretty much laid back at home:
One of the cats I have now will not tolerate me giving her any meds at all. She seems to have a hair trigger. I was trying to give her some antibiotic liquid, and I triggered a 10 minute meltdown that ended with her attacking my leg. If I had been barefoot, it would have been bad. She bit the back of my shoes about a dozen times each, screaming in rage. at 9 pounds, it's kind of comical, but still a little scary. 99% of the time, she's really cuddly and wants to be held and carried around: