New research studying the behavior of 9,000 dogs demonstrated that fearfulness, age, breed, the company of other members of the same species and the owner’s previous experience of dogs were all associated with dogs’ aggressive behavior towards humans. These findings can potentially provide important tools for understanding and preventing aggressive behavior.
Aggressive behavior in dogs can include growling, barking, snapping and biting. These gestures are part of normal canine communication, and they also occur in non-aggressive situations, such as during play. However, aggressive behavior can be excessive, making the dog a health threat to both humans and other animals.
The canine gene research group active at the University of Helsinki surveyed connections between aggressive behavior and several potential risk factors with the help of a dataset encompassing more than 9,000 dogs, a sample from a larger dataset from a behavioral survey dataset of nearly 14,000 dogs. The study investigated aggressiveness towards both dog owners and unfamiliar human beings. Dogs were classified as aggressive if they growled often and/or had attempted to snap at or bite a human at least occasionally in the situations described in the survey.
“Dogs’ fearfulness had a strong link to aggressive behavior, with fearful dogs many times more likely to behave aggressively. Moreover, older dogs were more likely to behave aggressively than younger ones. One of the potential reasons behind this can be pain caused by a disease. Impairment of the senses can contribute to making it more difficult to notice people approaching, and dogs’ responses to sudden situations can be aggressive.”
-Salla Mikkola, doctoral researcher University of Helsinki
Small dogs are more likely to behave aggressively than mid-sized and large dogs, but their aggressive behavior is not necessarily considered as threatening as that of large dogs. Consequently, their behavior is not addressed. In addition, the study found that male dogs were more aggressive than females. However, sterilization had no effect on aggressive behavior.
The first dogs of dog owners were more likely to behave aggressively compared to dogs whose owners had previous experience of dogs. The study also indicated that dogs that spend time in the company of other dogs behave less aggressively than dogs that live without other dogs in the household.
Significant differences in aggressive behavior between breeds
Differences in the aggressiveness of various dog breeds can point to a genetic cause.
“In our dataset, the Long-Haired Collie, Poodle (Toy, Miniature and Medium) and Miniature Schnauzer were the most aggressive breeds. Previous studies have shown fearfulness in Long-Haired Collies, while the other two breeds have been found to express aggressive behavior towards unfamiliar people. As expected, the popular breeds of Labrador Retriever and Golden Retriever were at the other extreme. People who are considering getting a dog should familiarize themselves with the background and needs of the breed. As for breeders, they should also pay attention to the character of dam candidates, since both fearfulness and aggressive behavior are inherited.”
-Professor Hannes Lohi, University of Helsinki.
At-a-Glance Summary of Research Findings:
Factors Associated with Dog Aggressiveness towards Humans
-Older dogs encountering sudden moves/situations
-Dogs of first-time dog owners
-Solitary dogs: Dogs that have no other dogs in the household
-Most aggressive breeds: Long-Haired Collie, Poodle (Toy, Miniature and Medium) and Miniature Schnauzer breeds
Journal reference: Salla Mikkola, Milla Salonen, Jenni Puurunen, Emma Hakanen, Sini Sulkama, César Araujo, Hannes Lohi. Aggressive behaviour is affected by demographic, environmental and behavioural factors in purebred dogs. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-88793-5