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What Makes an Aggressive Dog?

Study suggests it's not so much the breed as the gender, training, origin and owner's age


"The origin of the dog was a significant factor in aggression toward family members," said Mary Burch, Canine Good Citizen director for the American Kennel Club. "There was a 2.6 times increased risk in dogs obtained from rescue centers, and a 1.8 times increased risk from a combined category of 'other' sources, including pet shops and Internet sites, as compared to those obtained directly from breeders."

A lot of dog aggression is spurred by fear and anxiety, Zawistowski said. To avoid having an aggressive dog, he said, owners should properly socialize their pups by doing the following:

  • Leaving puppies with their litter until 8 weeks old, so they learn how to be social with other dogs.
  • Taking them to puppy kindergarten classes before 16 weeks old, so they become comfortable with other people and dogs.
  • Engaging them in positive-reinforcement training that teaches them things such as not jumping on people or pulling on a leash.

Older dogs that suddenly become aggressive might be experiencing pain due to an ailment. "If you're looking at a 6- or 7-year-old dog that's starting to be aggressive, you might want to look at whether the dog is starting to have some arthritis," Zawistowski said.

If you're worried that an unfamiliar dog might become aggressive toward you, you should pay attention to its body language, Burch said.

"Some pre-aggression behaviors are a direct stare, stiff posture, hackles up, ears or lips pulled back, baring teeth, growling, barking, lunging and snapping," she said. "Barking alone should not always be defined as aggressive behavior."

Burch criticized the British study for including barking as an aggressive behavior.

"It can be problematic for barking to be considered 'aggression' because barking can have multiple functions," she said, noting that dogs also bark to alert owners or to signal that they need something. "In my opinion, this overly broad definition, which includes barking, skews the data to show that there is an aggression problem in the U.K."


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