It’s not the dog, it’s the owner: Vets confirm why pets are aggressive

Despite being referred to as ‘man’s best friend’, many dogs have an aggressive side.

Now, a study has pinpointed exactly why some pups are more likely to be aggressive than others. 

According to scientists from Harvard University, the dog itself isn’t to blame – and instead, it comes down to their upbringing. 

In their study, the team analysed data from more than 4,000 dogs to understand why some pets show responses like snapping and biting. 

Their results revealed that dogs who experienced neglect as puppies are more likely to exhibit aggressive habits in adulthood. 

‘Dogs with a history of early adversity showed higher fear and aggression, with life history explaining at least as much variance in each behavior type as sex or neuter status,’ the researchers explained in their study, published in Scientific Reports. 

‘The adversity–aggression association was most pronounced for events occurring in the first six months of life, aligning with sensitive periods of behavioral development.

‘Furthermore, some breeds were at greater risk to the effects of adversity than others, suggesting an important genetic factor in fear and aggressive behavior.’

Here in the UK, five dogs – the Pit bull terrier, Japanese Tosa, Dogo Argentino, Fila Braziliero, and the XL Bully – are deemed so dangerous that they’re banned.

However, until now, there has been little research on exactly why certain dogs develop more aggressive behaviours than others. 

To get to the bottom of it, the team, led by Julia Espinosa, collected data from 4,497 dogs across 211 breeds. 

Owners were surveyed about their dogs’ responses to 45 common triggers of aggression – including sudden, loud noises, or strangers approaching the front door. 

They were also quizzed about any examples of adversity experienced during puppyhood, characterised as trauma, abuse, and negative behaviour. 

The results revealed that one third of the dogs had experienced some form of adversity within the first six months of their lives. 

And these dogs scored ‘significantly’ more highly for aggression in adulthood – regardless of their sex, age, or whether they’d been neutered. 

However, the researchers found key differences between breeds, with some more sensitive to early–life adversity than others. 

American Eskimo Dogs, American Leopard Hounds, and Siberian Huskies were found to have a stronger association between early–life adversity and fear. 

In contrast, Golden Retrievers and Labrador Retrievers showed very little difference in aggressive behaviours after early–life adversity.  

‘Some breeds [appear] to have increased risk for developing fearful and aggressive behaviors after early life adversity, particularly breeds historically bred for livestock guarding or bringing down game,’ the reseachers explained in their study. 

‘Conversely, other breeds seemed relatively unimpacted by early life adversity, suggesting a potential resilience to stress.’

Overall, the findings suggest that owners should be help accountable for their dogs’ actions. 

‘Future research in both basic and applied sciences can move toward identifying genetic variants linked to problematic behaviors to inform breeding practices that focus on temperament for particularly at–risk breeds, and support targeted rehabilitation strategies for dogs exposed to early life adversity using medication and behavior modification training,’ the researchers concluded. 

‘It can also guide rehoming decisions for particularly at–risk dog breeds by matching them with knowledgeable guardians in non–triggering environments.’

Speaking to the Daily Mail, Ryan Neile, Head of Behaviour Services at Blue Cross, warned that some dogs are ‘forever impacted by their previous experiences’. 

‘Even without traumatic and harmful experiences, puppies risk growing into fearful and anxious adults without early socialisation (specifically between 3 to 14 weeks) during which time it is essential that they are gently and positively exposed to everyday sights, sounds, people, other animals and new environments,’ he explained. 

‘When done correctly, these experiences help young dogs to grow into well balanced, resilient adults, better able to cope with the ups and downs of the life they are destined to experience as much-loved family pets.’