It isn't just animals, some people can sense when someone close to them has died or is dying. I "successfully" predicted the last three deaths in my family. The family has since distanced itself from me somewhat. When my great-grandmother died, my dad knew it when he was at work. When my papaw called him to tell him, he already knew. When you're really close to someone, you can feel it. As for animals, I think they're one step ahead of us, they don't have to be really close to the creature dying. They can just sense it.