A friend of mine has a long-haired Chihuahua mix named Mimi, and the two are inseparable; this dog goes everywhere with her. Most of the time, Mimi is a friendly bundle of personality, happy to greet anybody who wants to say hello. But when another dog is in the vicinity, Mimi goes crazy. She challenges every dog that crosses her path.
I have medium-sized dogs and one of mine acts the same way, so I’m not saying aggressive behavior towards other dogs is a size-specific issue. However, we’ve all heard of fearless small dogs that challenge large-breed dogs with reckless abandon. What causes this type of behavior?
The majority of experts believe this small-dog attitude is a combined result of nurture and nature. In other words, Mimi and other fearless small dogs have learned this behavior through interactions with their humans and the outside world.
People relate to small breed dogs differently than they relate to larger dogs. For example, when my friend walks Mimi and she barks or show dominance towards another dog, the other dog owner may giggle or say something like “that’s cute.” I can guarantee that if the aggressive, barking dog was a larger breed, say a German Shepherd or a Rottweiler, nobody would be smiling.