It's no secret that animals held in captivity in zoos and circuses can face severe physical ailments and injuries. But what about their emotional health? According to a new book, the consequences of captivity on animals' minds can be just as impactful -- and just as damaging.It's no secret that animals held in captivity in zoos and circuses can face severe physical ailments and injuries. But what about their emotional health? According to a new book, the consequences of captivity on animals' minds can be just as impactful -- and just as damaging.