06/04/2013 12:23 pm ET

Left-Pawed Dogs More Apt To Show Aggression Toward Strangers, Research Suggests

Getty Images

Ever wonder why Spot just can't seem to warm up to strangers? Being a left-pawed dog might have something to do with it.

New research published in the Journal of Veterinary Behavior suggests that dogs that show a preference for their left paws are more likely than dogs with no paw preference (ambilateral dogs) to show aggression toward people they don't know.

"I reported a statistically significant relationship between stranger-directed aggression and the presence of a paw preference," study co-author Dr. Luke Schneider, a post-doctoral research officer at the University of Adelaide in Australia, told The Huffington Post in an email. "Dogs without a paw preference demonstrated lower aggression scores. When I looked more closely at the dogs with a paw preference, it appeared that it was those dogs with a preference for the left paw that were driving this relationship."

The research found no evidence to support a relationship between paw preference and overall temperament.

In the study, a "Kong" dog toy was used to gauge the paw preference of 73 generally friendly pet dogs on a scale from -100 (strong preference for using left paw) to +100 (strong preference for using right paw). To assess the dogs' tendency toward aggression, the researchers had the dogs' owners complete a temperament questionnaire.

Aggression in dogs is mediated by many factors, of course, including the animals' age and health. But the researchers say the results of the study may reflect the lateralization of brain function in dogs -- and possibly, by extension, humans as well. The right and left hemispheres of the brain are known to control opposite sides of the body.

"The take-away message for me is that there appears to be more similarities between human and animal brains than we once thought," Schneider said.

Among pups, being left-pawed is not unusual. While only about 10 percent of humans are left-handed, there appears to be an even split between left-pawed, right-pawed, and ambilateral canines, Schneider said.