Chihuahua
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This is the smallest registered breed of dogs, originating from Mexico. They are quite stubborn, fierce, and temperamental. Definitely love to bark in their shrill, high-pitched manner. However they are loyal companions. The toughest to house train as they are the smallest breed, but when properly trained can be friendly and attentive. Best get a professional trainer for this dog. They do love to cuddle, but not with everybody. They have favorites, so take note. If you are not the favorite human, watch out.