I'm sure that same sense tells wild predators when their prey is weak. My dog, Sasha, however, isn't a predator. She accidentally caught a spider once and freaked out when it started moving. But when I'm upset and I'm trying to hang out alone, she sits outside by my bedroom door and cries. When I let her enter the room, she stares at me and whines. This might sound a little mean, but it makes me laugh. It's like she's insisting that I take a walk instead of moping around. Good thinking, little dog.