Like everyone mentioned above, horns are made of multiple layers of bone permanently fused to the skull that never stop growing. There is live tissue inside. Antlers are similar, except they are "dead bone" once the velvet is shed. Until then, they're not meant to break off.
So I'm really hoping that dragons horns are not horns at all, but either antlers or more like rhino horns (keratin) or elephant tusks (ivory/enamel). However, keratin horns and ivory tusks don't have live tissue, so they wouldn't hurt.....
That, and only antlers ever come back. ;w;
Anyway, I don't know what Maeda's plan is, but she's starting to grow on me.