I was 20 years old before I understood that our domesticated companions were not "dumb animals" running off some simplistic programming.
What brought this to mind was that while I was dog sitting a friend's German Shorthaired Pointers, I went to change the trash bag in the kitchen and I was careful not to pop the fresh bin liner open with a flick of the wrists.
It's not that the dogs would have minded, but I have been conditioned not to do that because of Holden. He's a (mostly) fearless tomcat. Even vacuum cleaners just make him warily decamp to another room, but there are two things that put him into an absolute panic: wielding a broom, and popping large sacks open with a flick of the wrist. Poor little fella must have had some traumatic experiences as a feral kitten.
Young me, who hadn't spent time around animal companions, wouldn't have noticed the difference between "wariness" and "terrified", but it's definitely a thing.
Sometimes I have to do things that make my animal friends uncomfortable, whether in the course of normal chores or For Their Own Good (taking kitty to the vet, for instance), and I do my best to reassure them that everything's cool when I'm doing it. But I do my damndest to not do things that actually terrify them.
