IMO Chihuahuas are the ultimate alert dog. They don't give a fuck who you are, if you get near their house, they're gonna bark up a shitstorm. They don't care if you're 12 inches tall, or 12 feet tall, chihuahuas think they're the baddest motherfucker in the hood and will confront anything that they think is a threat. If I'm ever in the backyard or far away from the front door where I can't hear anyone approaching my house and my chihuahua flips a shit, that means someone is out front. My grandma has the "uncle" of my dog, and he protects my grandma's house like you don't even fucking know. It's like he has fucking built-in sonar. Something makes a noise outside, his ears perk up, his eyes open wide, he jerks his head in the sound's direction, and his his pupils get really small. If the door bell rings, he'll tear ass across the house barking his fucking head off, leap onto the couch, and stick his head through the window blinds to see who's the asshole that just trespassed onto his porch.