If a dog is aroused into an aggressive response by a person or animal that he is prevented from attacking, he may redirect this aggression onto someone else. A common example occurs when two family dogs become excited, bark and growl in response to another dog passing through the front yard. The two dogs, confined behind a fence, may turn and attack each other because they can't attack the intruder. Predation is usually considered to be a unique kind of aggressive behavior, because it's motivated by the intent to obtain food, and not primarily by the intent to harm or intimidate. Individual Variation Dogs differ in their likelihood to show aggressive behavior in any particular situation.
Some dogs tend to respond aggressively with very little stimulation.
Others may be subjected to all kinds of threatening stimuli and events, and never attempt to bite. The difference in this threshold at which a dog displays aggressive behavior is influenced by both environmental and genetic factors. If this threshold is low, a dog will be more likely to bite. Raising the threshold makes a dog less likely to respond aggressively. This threshold can be raised using behavior-modification techniques.