How about baby murderers? Do they have to register? Nah. We’ll protect unborn dolphins but slaughter our unborn children.
Also a good point!
Abortion is an entirely different subject. Why in the world would you bring it up here? The two are in completely different universes.
Now if you had said something about those who abuse and hurt small children; I'd say the punishment should be to put them away for life. They too have proven themselves to be inhuman and not deserving of the rights humans have.
Maybe one day humanity will evolve to the point when being human comes with certain responsibilities which when abused would result in them given non-human status without the rights humans have. They could be euthanized, for example, for the good of the herd of other non-humans. Maybe they would be called post-humans so it would be clear they had done something so bad they gave up their humanity and became a sub-human.
Animal abusers should be hung by their ears until dead.