I don't really understand this statement, the word animal has a definition. The first/second sentence has nothing to do with the point about the dog being destroyed. Of course owners are legally and morally responsible for their pets, what is your point?
Well trained dogs are more predictable than any human. I know you don't want to believe it, but you can put a reasonable amount of trust in a trained dog, and not be concerned that it will somehow revert to a feral state. This is why we trust trained dogs with security work, with rescue work, with guiding blind people across the street, with small children who have seizures or social anxiety... list goes on. But I suspect you are just wanting to somehow put your foot down on this wholly-provable point, so all I can say is what I've listed above, and I hope you do more reading. The answer is no, trained dogs are not ticking timebombs.