As far as im aware, dogs are the only truly domesticated animal, in that their behavior when trained, and obviously genetics, is significantly different from their wild counterparts. Even very large dogs can be trusted if youre treating them right. Wild cats, horses, pigs, etc behave about the same as trained ones, minus being more comfortable around humans and having habits formed around human behaviors like when youre going to feed them or something. Cats treat us the way they treat eachother, with deference to the fact youre more than 20 times as large as they are, which makes you the boss, but youre still just another cat to them. That or they dont have the ability to develope behavior sets for other animals
Horses, notably, will kick you to death if you upset them. Or just accidentally. Very important to be their best friend and have their full trust, and pay attention to their cues, and not sneak up on them, at all times. Then you can train them, you just have to train yourself at the same time. I could never let you guys in my horse pasture without me in there, you could get seriously hurt, just because the horses dont trust you. Wild horses share pretty much all the same behaviors. Zebras, from what ive seen on camera, actually act a fair bit like horses. They just dont like you. Im willing to bet you can train any animal to act like its domesticated, just dont expect them to drop all their natural behaviors, because they wont. In that way the concept of domestication, i think, really does apply exclusively to individuals that have been trained to some degree and are comfortable with humans, and being handled by humans trained to interact with them, and that any animal that isnt trained, even a dog, could be extremely dangerous and effectively wild; rather than behaving as we want them to, they are behaving as their instincts and life experiences dictate.