Why Does a Dog Go From Calm to Aggressive?

Aggression in dogs means harmful or threatening behavior, which is directed at another living creature. Symptoms of an aggressive dog may include growling, snarling, nipping, biting, snapping, or lunging. Dogs can go from calm to aggressive for a number of reasons. Once you learn what triggers a dog to become aggressive, you can focus on the problem.

  1. Fear

    • A nervous dog that believes he is in danger of being harmed may become aggressive. He may also be fearful when another dog approaches him. This is common when the dog feels he cannot escape. Pet Place notes, "Active, unpredictable children may also stimulate this type of aggression." This type of aggression is usually caused by a lack of socialization at an early age.

    Protective

    • A dog may become aggressive toward people or other animals he feels may hurt his family or pack.

    Territory

    • A dog may become aggressive if someone invades his territory, owner or pack member. A dog who urine marks in different areas of the neighborhood may believe that to be his area and become aggressive when someone or another animal goes near it. This is similar to inter-male aggression, which is between adult males involving territory or dominance. Inter-female aggression commonly occurs between adult females living in the same household.

    Possession

    • Dogs may suddenly become aggressive over materials such as his food or toys.

    Predatory

    • Predatory aggression occurs when a dog sees something he considers prey. Dog Listener notes, "One of the key factors that distinguish predatory aggression from other forms of aggression is that movement often is the trigger." This would be anything quick moving such as a car or bike.

    Provoked

    • Redirected aggression occurs when a dog is provoked by a person or animal he cannot attack. As a result he may take his aggression out on someone else. The Humane Society of the United States notes, "Two family dogs may become excited, and bark and growl in response to another dog passing through the front yard; or two dogs confined behind a fence may turn and attack each other because they can't attack an intruder."

    Warning

    • It's important to make sure a dog never has dominance over a child or adult. Aggression should be handled by a reputable animal trainer or an animal behaviorist. Contact your veterinarian as he may be able to recommend a professional trainer in your area.