What if a mouse is in the house? What would the dog do? He would be stupid like all mutts. On the other hand, a cat would go after it. Also, rarely, birds can get in the house. And dogs STILL fail this step. But cats will chase the bird until it’s either out of the house or dead. So that’s why cats can be very good at protecting the house. Because a mouse could spread diseases and rarely kill somebody. But the cat won’t let THAT happen.