I took my year old cat Milo and our 4 year old spayed female Mimi outside (we are temporarily living in an RV) so I put them in their holsters - and made sure Mimi's was good and snug around her neck and belly, so she couldn't wriggle out of it - we walked around the RV site for about 10 min. then went back inside, still in the holsters and with the leashes on, while I went closed the RV door. Then I quickly went back in to take off the holsters.
When I tried to get Mimi's holster off I accidentally pulled her fur - she kind of screamed a little, flipped on her back, claws extended and hissed at me. I still had hold of the leash and tried to reach in again, but she meow-screamed at me again.
Suddenly, Onyx (11+ yo neutered male, 20 lbs, normally sedentary as possible) leaped off the bed, and attacked Mimi from behind - pretty fiercely! I don't know if he was trying to protect me, or if the noise she made scared him into thinking she was a strange wild animal - what's up with that?