Understanding Canine Aggression Better

Aggression in dogs, although normal and natural, is considered undesirable behavior, especially when directed toward humans. A new study shows that temperament, age, breed, training, and the owner’s experience are all factors that come into play when it comes to aggression—toward humans or other dogs—and that these factors can negatively impact a dog’s well-being.   Aggression is a common behavior in domestic dogs. While growling, barking, or threatening postures are signals that are part of normal canine communication, they are not perceived positively by humans. Aggressive behavior can also become excessive and lead to biting, making the dog a threat to humans and other animals. This undesirable behavior often leads to the abandonment or even euthanasia of the dog responsible for an aggressive incident, even though the problem can often be resolved through medical and/or behavioral treatment. In some countries, certain dog breeds are even banned or subject to specific restrictions in order to minimize the potential risk of biting or aggression. Most of the time, these problematic behaviors are a sign of fear, pain, or frustration that compromise the dog’s well-being. Therefore, it is important to understand the factors and circumstances underlying aggressive behavior in dogs. A research group at the University of Helsinki studied the links between the behavior of some 9,000 pedigree dogs—1,791 of which were classified as aggressive—and several potential risk factors. This study focused specifically on aggression toward humans, whether owners or strangers. Dogs were classified as aggressive if they frequently growled and/or had attempted to bite a person, at least occasionally. The authors thus identified factors related to the dog’s behavioral development and environment that are likely to lead to aggressive behavior toward humans. The researchers demonstrated that fear, age, breed, interactions with other dogs, and the owner’s experience influence dogs’ aggressive temperament toward humans. Aging or fearful dogs are more likely to exhibit aggressive behavior. In older dogs, these aggressive reactions may be caused by pain or by a decline in the acuity of certain senses, such as vision, which affects how they perceive their environment. Small dogs are also often more aggressive or prone to biting, but their behavior is not necessarily viewed as threatening given their small size, meaning it is corrected less frequently than in medium- or large-sized dogs. Furthermore, the study confirms that male dogs are more aggressive than females. However, contrary to popular belief, sterilization has no effect on this aggressive behavior. The family’s first and only dog also appears to be more prone to aggression. Conversely, dogs that spend more time with other dogs tend to behave less aggressively than isolated and fearful individuals. However, the causal link remains uncertain. Finally, breed plays a significant role in aggressive temperament, suggesting a genetic basis for this behavior. The Collie, the Poodle (toy, miniature, or standard), and the Miniature Schnauzer top the list of breeds considered the most aggressive. At the other end of the spectrum, popular dog breeds such as the Labrador and the Golden Retriever are associated with a much lower likelihood of aggression. Overall, several criteria should be considered to improve the relationship between dogs and humans and reduce canine aggression. Genetic factors underlying a high prevalence of aggressive behavior could be addressed through more targeted selection of breeding stock, in order to prioritize the least aggressive and least fearful animals. Other factors at play include the owner’s role (choosing a breed suited to their lifestyle, having multiple pedigree dogs instead of just one, etc.), as well as the dog’s living conditions and development (socialization and interaction with other dogs and humans, pain management in older dogs, etc.).