Aggression is the most serious and dangerous behavior problem that dog owners face.  Because there are many different types of aggression, making a diagnosis, determining the prognosis for safe and effective correction, and developing an appropriate treatment plan are usually best handled by working with a veterinary behaviorist.  Some medical conditions can contribute to aggression, so as a first step, your dog should have a complete physical examination.  Once your pet has a clean bill of health, determining which type of aggression your dog displays is needed to treat the problem effectively.  Types of aggression include dominance/conflict-related, fear, possessive, protective and territorial, maternal, play, redirected, pain induced, medical, or learned.  Some dogs also display more one type of aggression.

One of the most common types of aggression is dominance or conflict-related aggression, which is related to the relationship between the dog and the family members.  To achieve security and cohesiveness in a group or pack, dogs develop a hierarchy, with social control maintained through dominance displays, threats, and deferential responses between pack members.  Although it is unclear if the concept of hierarchy applies to dog-human relationships, your dog is limited through genetics and learning to communicate with canine postures, body language, and actions.

Fear aggression arises when a dog is exposed to people or other animals that the dog is unfamiliar with or to those that have been previously associated with an unpleasant or fearful experience.  Possessive aggression is directed toward people or other pets that approach the dog when it is in possession of something that is highly desirable, such as a favorite chew toy, food, or treat.  Protective and territorial aggression can be exhibited toward people or other animals that approach the pet’s property or family members.  Maternal aggression is directed toward people or other animals that approach a mother dog with her puppies.  Once the litter of puppies is weaned and the dog is spayed, the problem is unlikely to recur.  Play-related aggression is commonly seen in young dogs toward people or other pets.  Common signs of play-related aggression are overly rambunctious play, along with grabbing, nipping, or biting of people or their clothing.  Aggression that is directed toward a person or pet that did not initially evoke the aggression is called redirected aggression. This typically happens when the dog awakens and another person or pet interferes or approaches.  Pain-induced aggression can be seen in an injury or from handling or contact that causes pain or discomfort.  Aggression associated with medical disorders can be seen at any age, come on relatively suddenly, and may not seem to fit behaviors that are typical of dogs.  Painful conditions might also increase the pet’s irritability. Although learned aggression can refer to dogs that are intentionally trained to act aggressively, learning and conditioning are also important components of many other forms of aggression.

Written and reviewed by John A. Bukowski, DVM, MPH, PhD and Susan E. Aiello, DVM, ELS