While some dog breeds have unfortunate reputations for being more aggressive than others, veterinarians and other animal experts have long been skeptical about this.
A new study of 665 domestic dogs (Canis familiaris) in Brazil also points towards factors other than breed having stronger influences over this 'problematic' behavior.
"The results highlight something we've been studying for some time: behavior emerges from interaction between the animal and its context," explains University of São Paulo ethologist Briseida de Resende.
"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."
Previous research defines canine aggression "as a dog's tendency to both act threateningly, with raised hackles and tail, bared teeth, heightened body posture, growling and to act aggressively, by attacking or biting".
Through a series of questionnaires for owners, University of São Paulo ethologist Flavio Ayrosa and colleagues found several strong associations.
The good news is that dogs with owners who play with them and take them for regular walks were likelier to be less aggressive towards owners and strangers. Training levels were a strong indicator too.
But the absence of aggression towards strangers was 73 percent more likely when the dog's owner was female. The sex of the dog also appears to have a role, with a 40 percent lower likelihood of aggression towards owners from females rather than male dogs.
Some physical traits also showed associations, which may explain why many point their fingers at specific breeds. Dogs with unhealthily short snouts, known as brachycephalic breeds, were 79 percent more likely to display aggression towards their owners.
What's more, as height and weight decreased, undesirable behaviors, including non-social fear, attention-seeking behaviors, and hyperactivity, also increased, as seen in past studies.
But a combination of these different factors was the best predictor, rather than just a body characteristic or an environmental one alone.
"We found relationships, but it's impossible to say which comes first. 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," says Ayrosa.
"Traits such as weight, height, cranial morphology, sex, and age influence the interaction between dogs and their environment. They may spend more time inside the home because of them, for example."
Regardless, it's important to remember that aggression is a natural form of communication for all animals, and like all behaviors, it is complex.
While no one wants their companion animals to rely on aggression as a first response when feeling worried, stressed, or threatened, sometimes there is a valid reason for instances of aggression that can be resolved, such as pain.
"Rather than determining aggression to a single factor common to the species or specific breeds, our results reinforce how individual behavior, combined with dogs' unique genetics, physiology, life experiences, and environmental contexts, interact throughout development to produce the observed expression patterns," the team concludes in their paper.
This research was published in Applied Animal Behaviour Science.