Canine aggression is a subject that can be difficult for dog owners and dog lovers to understand. Not only can it be scary, but there are also many reasons that a dog might engage in aggressive behavior. Fortunately, there are very few dogs that are prone to aggression despite the situation. As dog lovers, it's important for us to think of aggression in terms of aggressive behavior instead of aggressive dogs or breeds. In most cases, these behaviors correspond directly to specific relationships, events, or environments. Understanding the contributing factors and types of aggression can often help in the treatment of aggression.

Resource Guarding
This refers to aggressive behavior when a dog is guarding a valued resource. This can be anything - food, toys, their bed, and even their owner. Usually these warning signs include, growling, snarling, or air-snapping, but in some cases can lead to biting.

Territorial
This form of aggression is most common when other guests, animals, or dogs are allowed in the dog's "territory"  without an owner present. In this situation, the owner needs to communicate clearly that these visitors are not threats, and ultimately, make it clear that the owner is the one in charge of the territory.

Protective
Protection aggression occurs when a dog perceives a threat to their family. This is related to territorial aggression.

Misplaced
Also referred to as "redirected aggression", this happens when a dog reacts to a stimulus that they cannot interact with. For example, a dog that sees another dog through the widow might react aggressively towards a person or pet in the house because they cannot direct that aggression towards the stimulus, i.e. the dog outdoors.

Frustration
This type of aggression can overlap with misplaced aggression and occurs when something prevents the dog from doing what they need or want to do. Impulsively, the dog will react upon the nearest bystander. This common form of aggression is found in dogs that get over-excited. For example, a leashed dog that cannot approach another dog may lash out due to frustration.

Play-escalation
Similar to misplaced aggression, this occurs when a dog gets over-stimulated during playtime with another dog, pet, or human and suddenly switches over to aggressive behavior.

Pain-induced
Dogs in pain may try to bite anyone or anything they believe has caused them pain or will cause them more pain. In some cases, dogs will direct this aggression towards themselves, like biting their own foot that is caught in a trap. This type of aggression is deeply rooted in canine survival instinct, as are most other aggressive behaviors.

Fear-related
These dogs display aggressive behaviors when afraid, and may bite when cornered. They may even take an offensive position once they realize the likelihood of having the person or threat retreat.

Social Status
Often called dominance aggression, this type of aggressive behavior is designed to increase the dog's social status among its peers. Usually, peers are other dogs. However, dogs that have not been raised under consistent and kind human leadership can exhibit aggression towards humans.

Intra-sex
This refers to aggression among dogs who are same sex - females only showing aggression towards other females, and males only showing aggression towards other males.

Hormone Driven
Usually, this form of aggression refers to aggressive behavior caused by female dogs in heat. It can involve other males fighting over a possible mate, or the female, herself, fighting with dogs of both sexes.

Medication-induced
Some medications, like steroids, can cause aggressive behavior in dogs, much like steroid-induced psychosis found in humans.

Health-related
Medical conditions, like thyroid imbalance or ear infections, can cause aggression, as well.

Learned Behavior
Aggression can be learned, be it intentionally or unintentionally. A dog that is trained to attack humans is an example of intentionally learned aggressive behavior. A fearful dog whose behavior has been reinforced by its owner, like petting them when they growl or shy away, is a form of unintentionally learned aggression.

Predatory 
Some dogs have a naturally higher prey drive than others. The natural instinct to hunt takes over, causing them to nip or bite. This behavior is often directed towards other pets, wildlife, or children.

How to Curb Aggression
The best way to nip aggression in the bud is to expose your pup to different situations from the beginning. Socialize them with other dogs, animals, and people, and take time to train them. This can help prevent aggression in the future. However, with adopted dogs this isn't always an option.

Understanding the cause of aggression can help you address the problem. In many cases, there's more than one reason your dog is being aggressive. Set up an appointment with an experienced behaviorist, and give them a history of your dog's past behavior, if possible. If your dog suddenly resorts to aggressive behavior, schedule an appointment with your vet. Your furbaby might be in pain or in need of medical attention.

Whether you see a specialist, vet, or both keep a detailed list of instances and signs of aggressive behavior. This can help determine the best course of action for modifying your dog's behavior. Most behaviors can be treated through time, patience, and training.