A recent study looked at the prevalence of aggression towards humans seen in dogs in different situations and assessed potential risk factors for such dogs. The study was done by researchers from the School of Veterinary Sciences of the University of Bristol.

For this study, researchers distributed questionnaires to 15,000 dog owners, out of which 4,000 were completed and used for the study. The researchers analyzed the data and found that aggression towards strangers was more common than aggression towards family members. Around 7 percent of owners said that their dogs barked, growled, lunged or bit people who came to the house and 5 percent reported the same when meeting people out during walks. Only 3 percent of owners said their dogs were aggressive towards family members.

Also, the study highlighted that most dogs showed aggression in just one of such situations, indicating that rating dogs as generally ‘vicious’ or ‘safe’ is a misconception and aggression in dogs is a learned response in certain conditions.

Dr. Rachel Casey, Senior Lecturer in Companion Animal Behavior and Welfare, said, "Dog owners and members of the public need to be aware that any dog could potentially show aggression if it is anxious or feels threatened, even when it has never done so before. On the other hand, dogs which have shown aggressive signs in one situation are not necessarily 'dangerous' when in other contexts - an important consideration in the assessment of animals, such as in rehoming centers."