How Aggressive Is Your Canine?

Nature or Nurture
Nagja Bamji says that her dachshund, Ronny, is far from aggressive. Ronny gives other dogs a wide berth, loves kids and recently backed off when a squirrel hissed at him, says Bamji, 46, a homemaker in Fremont, Calif. You also might find that your dog doesn't fit the profile developed in this study.

"We do have breed differences; there is no question," says Dr. Gail Clark, a canine behavioral psychologist based in Fort Collins, Colo. "But there is a tremendous amount of factors in dog behavior."

She explains that environment and training, as well as breed, help determine how your dog behaves. For example, she says, the owners of little dogs tend to pick them up frequently in threatening situations. Perched high in their owners' arms, the little dogs feel mighty brave. When the dogs return to the ground, they might feel defensive and threatened. How you perceive your dog's breed, regardless of size, might therefore influence the way you train or handle your pal, thus affecting your canine's long-term behavior, says Dr. Serpell.

Where you obtain your puppy can be another significant factor, says Dr. Serpell, who recommends finding a reputable breeder, visiting the breeder and even meeting your pup's parents, if possible. Dogs produced in puppy mills often have behavioral problems, he says. Puppies tend to be removed from their mothers and littermates too soon, and they don't have enough positive human contact in their early weeks. Their mothers often are kept in highly stressful environments during their pregnancies, which likely has a longstanding impact on the puppies, says Dr. Serpell.

Individuality Can Overcome Statistics
Dr. Serpell believes that the next step for researchers is to understand the factors that contribute to individual dogs behaving aggressively. When it comes to this study, it's important to not paint every dog with the same brush, he thinks. "The No. 1 thing we'd like you to take from the study is it's based on breed averages," says Dr. Serpell. "Branding a breed as dangerous or aggressive is inappropriate. Within any breed, you're going to find many, many individuals that are really nice and well-tempered."