Dog aggression is any behavior meant to intimidate or harm a person or another animal. Growling, baring teeth,
snarling, snapping and biting are all aggressive behaviors. Although aggressive behaviors are normal for dogs,
they’re generally unacceptable to humans. From a dog's perspective, there’s always a reason for aggressive
behavior. Because humans and dogs have different communication systems, misunderstandings can occur
between the two species. A person may intend to be friendly, but a dog may perceive that person's behavior as
threatening or intimidating. Dogs aren’t schizophrenic, psychotic, crazy, or necessarily "vicious," when displaying
aggressive behavior.
Because aggression is so complex, and because the potential consequences are so serious, we recommend that
you get professional in-home help from an animal behavior specialist if your dog is displaying aggressive behavior.
Our Behavior Helpline can’t assist you with aggressive behavior problems (see our handout: “When The Behavior
Helpline Can’t Help”).
Types of Aggression
Dominance Aggression: Dominance aggression is motivated by a challenge to a dog's social status or to his
control of a social interaction. Dogs are social animals and view their human families as their social group or
“pack.” Based on the outcomes of social challenges among group members, a dominance hierarchy or
"pecking order" is established (see our handout: “Dealing With Dominance In Dogs”).
If your dog perceives his own ranking in the hierarchy to be higher than yours, it’s likely that he’ll challenge you in
certain situations. Because people don’t always understand canine communication, you may inadvertently
challenge your dog's social position. A dominantly aggressive dog may growl if he is disturbed when resting or
sleeping, or if he is asked to give up a favorite spot, such as the couch or the bed. Physical restraint, even when
done in a friendly manner, like hugging, may also cause your dog to respond aggressively. Reaching for your
dog's collar or reaching out over his head to pet him, could also be interpreted by him as a challenge for
dominance. Dominantly aggressive dogs are often described as "Jekyll and Hydes" because they can be very
friendly when not challenged. Dominance aggression may be directed at people or at other animals. The most
common reason for dogs in the same family to fight with each other is instability in the dominance hierarchy (see
our handout: "Canine Rivalry").
Fear-Motivated Aggression: Fear-motivated aggression is a defensive reaction and occurs when a dog believes
he is in danger of being harmed. Remember that it’s your dog's perception of the situation, not your actual intent,
which determines your dog’s response. For example, you may raise your arm to throw a ball, but your dog,
perceiving this to be a threat, may bite you because he believes he is protecting himself from being hit. A dog
may also be fearfully aggressive when approached by other dogs.
Protective, Territorial And Possessive Aggression: Protective, territorial and possessive aggression are all very
similar, and involve the defense of valuable resources. Territorial aggression is usually associated with defense of
property. However, your dog's sense of territory may extend well past the boundaries of “his” yard. For example, if
you walk your dog regularly around the neighborhood and allow him to urine-mark, to him, his territory may be the
entire block! Protective aggression usually refers to aggression directed toward people or animals that a dog
perceives as threats to his family, or pack. Dogs become possessively aggressive when defending their food, toys
or other valued objects, such as Kleenex stolen from the trash!
Redirected Aggression: This type of aggression is relatively common, but is a behavior that pet owners may not
always understand. 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.