Researchers at the University of Sao Paulo studied 665 pet dogs from 57 breeds, all varying in size.
The dog owners filled out online questionnaires about themselves, the traits of their dog, and the dog’s aggressive tendencies, such as barking or attacking.
The findings showed that owners thought their dogs were more well-behaved and less aggressive when they were heavier. Researchers also found that a dog’s tendency to be aggressive fell by 3% for every kilogram of body mass.
The most aggressive breeds were thought to be small, brachycephalic dogs with short snouts, such as Bulldogs and Pugs. Breeds having more intermediate skulls, such as Labradors, Golden Retrievers, and Beagles, are categorized as mesocephalic breeds.
Flavio Ayrosa, the first author of the study, said, “Aggressiveness toward the owner was 79% more likely among brachycephalic than mesocephalic dogs.”
“In the case of the factor ‘walking the dog,’ for example, it may be that people walked their dog less because the animal was aggressive, or the dog may have become aggressive because the owner didn’t take it out enough,” he said.
“Traits such as weight, height, cranial morphology, sex and age influence the interaction between dogs and their environment.” Researchers hope the findings will help owners understand that a dog’s aggressive tendencies are a result of the pet and its environment, and not just the animal itself.
“The environment and the owner-pet relationship, as well as morphology, are all factors that influence how pets interact with us and how we interact with them,” said Professor Briseida de Resende, another author of the study.
Ayrosa stated that even while researchers discovered a cause-and-effect relationship with their findings, it is impossible to determine whether a dog’s behavior or its environment came first