There are very few dogs who are prone to aggression regardless of the situation. That’s why it’s helpful to think in terms of of aggressive behaviors rather than aggressive dogs when trying to reduce your dog’s tendencies to growl or bite. Usually these behaviors are related to specific events, relationships or environments.
Keeping this in mind, here are some terms commonly used when labeling aggressive behavior:
- Resource guarding: Many dogs will exhibit aggressive behaviors if guarding a valued resource (which can be anything, not just food or a toy, it could be their bed or even their owner.) Usually these dogs are giving “warnings” (growling, snarling, air-snapping) but they can be pushed into biting if the warnings are not heeded.
- Misplaced, sometimes called displaced, or frustrated aggression: Commonly seen when dogs become overly excited, such as when the owner arrives and dogs congregate at a gate, bump into one another, and then get into a fight.
- Play-escalation: Very similar to frustrated aggression, involving a dog that becomes overly excited during play (with another dog or with a person) and suddenly switches over to aggressive behavior.
- Territorial: Most common when dogs are allowed in any “territory” without an owner present, or if the owner is not communicating clearly to the dog that they, the owners, are the ones ultimately in charge of the territory.
- Pain-induced: Dogs trying to escape from something which has caused them pain may inflict a bite on anyone present, sometimes even directing aggression toward themselves (such as the dog who bites off his foot when it is caught in a trap.) This type of aggression is part of a canine’s survival instinct, as are most aggressive behaviors.
- Fear-related: These dogs display aggressive behaviors when afraid, and may actually bite if cornered with no escape. Sometimes fearful dogs progress to taking an offensive position, if they realize that aggressing toward people (as opposed to backing away) is successful in making the person retreat.
- Social status: Includes behaviors designed to up the dog’s social status among his peers. Usually peers would mean other dogs, but at times dogs who have not been under consistent and kind human leadership will exhibit socially driven aggression toward human beings (often called dominance aggression).
- Intra-sex: Female dogs displaying aggression only toward other female dogs, and male dogs aggressive toward other male dogs.
- Hormonally driven: Usually hormonally driven aggression refers to aggression caused by a female dog being in season. It can involve males fighting due to the presence of a female in heat, or the female herself fighting with other dogs of either sex.
- Medication-induced: Medications, particularly steroids, may cause certain dogs to display aggressive behavior (similar to a condition in humans called steroid-induced psychosis).
- Health-related: Medical conditions, such as thyroid imbalances, even ear infections, can cause aggressive behaviors in dogs.
- Learned behavior: Aggressive behavior can be learned, intentionally or unintentionally. A dog that has been trained to attack people would be an example of intentionally learned aggressive behavior. A fearful dog whose behavior has been reinforced when he is afraid (for example, the dog growls and shies away, his owner tries to calm him by petting, which accidentally reinforces the behavior) would be an example of unintentionally learned behavior.
If your dog exhibits aggressive behavior, try not to label it too quickly. Often there is more than one root cause, so it is best to make an appointment with an experienced canine behavior counselor or behaviorist, and give them a thorough history of your dog’s past behavior.
Be sure to include details about any incidents of aggressive behavior (even minor warning behaviors like growling) so that a successful behavior modification program can be developed. With careful diagnosis, treatment, and time, these behaviors can usually be trained out of your dog.
Source: Adapted from the American Animal Hospital Association