3. Yorkshire Terrier - Top 10 Most Popular Dog Breeds

The Yorkshire Terrier belongs to a group of canines which were first bred to be used as hunters. These small feisty dogs were used to chase vermin—small burrowing creatures like rats and mice. Despite its size, a Yorkshire Terrier is courageous and displays an alertness that makes them perfect as guard dogs. They are very territorial but they can live harmoniously with other dogs as long as they are introduced gradually and carefully. Although they are affectionate with members of the pack, they can also become suspicious and aggressive towards strangers, both humans and animals. They can develop the so-called Small Dog Syndrome when their owners allow them to get away with negative behaviors. They can then become increasingly anxious, overprotective, and yappy.