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New research reveals which dog breeds are the most aggressive, and looks at what other characteristics can contribute to aggression.

Scientists at the University of Helsinki studied behavior of more than 9,000 dogs covering some two dozen breeds, the Daily Mail reported. They found small dogs were more likely to behave more aggressively than mid-sized and large dogs.

Scientists also found male dogs are more aggressive than females, and neutering them has no impact on making them more or less aggressive. In addition to size and sex, the study also looked at age and fearfulness as factors in aggressive behavior.

Rough collies came in first on the list for probability for aggressive behavior, followed by the miniature poodle, miniature schnauzer, German shepherd, and the Spanish water dog.

The study was published May 3 in the journal Scientific Reports.

This segment aired on KTLA 5 Live on May 4, 2021.

This graphic was included with the study "Aggressive behaviour is affected by demographic, environmental and behavioural factors in purebred dogs" from researchers at the University of Helsinki, published May 3, 2021, in Scientific Reports.
This graphic was included with the study “Aggressive behaviour is affected by demographic, environmental and behavioural factors in purebred dogs” from researchers at the University of Helsinki, published May 3, 2021, in Scientific Reports.