An aggressive dog barks at a potential threat.

Aggression in Dogs

Aggression in dogs is characterized by dangerous and unpredictable behavior, both between two dogs or people within the household. The first step toward resolving this issue is identifying the problem. Once aggression is identified as the specific cause, steps can be taken to rehabilitate the pet and keep yourself and other animals safe.

The most common aggressive behaviors include:

In some dogs, aggression can be harder to identify, since they can mimic fear behaviors, like hiding, cowering, and avoiding eye contact.

Types of Aggression

Dogs are aggressive for a variety of reasons. Finding the underlying cause can help to pinpoint training measures and areas to avoid.

Aggression is broken into these six categories by the ASPCA:

Territorial/Possessive Aggression

Territorial or possessive aggression is seen when a dog is defensive over something they believe to be their own. This includes yards, houses, toys, food, beds, or anything that a dog considers a resource. This type of aggression has also been called resource guarding.

Dogs are trying to protect something they deem valuable and are willing to fight for it. This is most commonly seen between household pets, but can also be directed towards an adult or child in the household. This type of aggression can be managed, but is frustrating for those with multiple pets in the household. The ASPCA has a staged approach to help with food guarding that is quite helpful.

Protective Aggression

This type of aggression is a defense mechanism to protect a person or persons. This can be a trained behavior, displayed by working dogs or guard dogs that are encouraged and trained to protect. Protective aggression develops over time, especially when harm is perceived towards a particular loved one.

Fearful Aggression

Dogs that are fearful can use aggression as a defense mechanism. In situations where a dog is frightened, they will often retreat or hide, but if pushed, they will react aggressively to protect themselves from the threat. They are not overtly aggressive, but may become aggressive if their fear escalates.


Dogs that are unsocialized use aggression as a defense mechanism secondary to fear. This is common in feral dogs with minimal human interaction. They will act aggressively due to fear of the unknown. This is one reason why puppy and adult dog training classes are important to allow socialization and exposure to different types of dogs, people, and environments, in an effort to expand their knowledge base. Socializing dogs can minimize their fear responses.

Defense Aggression

Defense aggression relates to sensing danger. This can be a reaction to another dog’s aggression or a reaction to a perceived threat. Defense aggression overlaps with fear and unsocialized aggression.

Painful Aggression

Pain associated aggression is a reaction to an injury or wound. They anticipate pain with handling and will react aggressively. This is the easiest type of aggression to correct. Once the source of pain is identified and resolved, this behavior should also resolve.

After you have identified aggressive behaviors and isolated what is causing the aggression, further steps should be taken to address behavioral issues. However, ALWAYS EXHIBIT CAUTION AND SAFETY WITH A DOG THAT HAS AGGRESSIVE TENDENCIES, since aggressive dogs can inflict severe injuries. If you are concerned about your safety, it is best to enlist the help of a professional trainer.

Preventative Tips

The easiest way to avoid aggression in dogs is stopping unwanted behaviors before they develop. This is commonly achieved in puppies and young dogs during their early developmental stages. Once your puppy has been vaccinated, they can start puppy school. Puppy classes are incredibly important in the socialization of an animal. In these classes, dogs are exposed to other dogs, people, and environments. This helps to minimize fearful behavior. Puppy classes also help to create a strong bond between the dog and their owner. They learn basic commands, leash skills, off-leash commands, and safety words.

As your puppy grows into a wild teenager, continuing training classes helps to reiterate the skills learned in puppy classes, while improving socialization. Often, classes with older puppies and adults help to teach dogs skills and tricks to keep their minds busy and lessen their urge to be destructive. During classes, dog owners also have a trainer on hand to address concerns and frustrations. Professionals can help address these concerns, and may offer at-home exercises to further develop your dog’s social skills.

When your dog is old enough, spaying or neutering is encouraged. Intact male and female dogs are more likely to exhibit aggressive behaviors when compared to their altered peers. Intact dogs are more likely to exhibit protective and territorial behaviors, roam unsupervised for mates, and put themselves at risk of injury.

What to Do If A Dog Is Behaving Aggressively

If your dog is already exhibiting aggressive behaviors, steps need to be made to correct their anti-social nature. Safety is always of the utmost importance, so remove yourself, children, and other pets from the area occupied by an aggressive canine. If these behaviors are situational, such as aggressiveness related to a toy or a particular dog, the instigating item should be removed. From that point on, the dog and its owner need to work with a veterinarian and trainer to prevent further aggressiveness.

If a dog has injured a person, it needs to be reported to the local health department, due to zoonotic risk of rabies. In addition, local animal control can help establish the next steps, which may mean quarantining at home, depending on the dog’s rabies vaccine status. A dog that has bitten a person needs to be isolated from children to prevent further injuries. A professional trainer should be involved and create the safest plan for your dog, in hopes of minimizing the likelihood of recurrence. If a dog has shown aggressive behaviors, caution should be taken to prevent further aggressive action. Also, a trainer and veterinarian should know a dog is aggressive before interacting with them to minimize further injury.

If a dog has injured another animal, this needs to be reported to local animal control. In these situations, rabies vaccine status should be confirmed for all parties involved and booster shots need to be administered. If a dog has a tendency to be aggressive towards other dogs or animals, they should always be leashed and avoid triggering interactions. For example, if a dog has shown aggression toward similar sized dogs, they should not be permitted to encounter dogs of this size. Avoiding interactions with other dogs and always having them on a leash is key to minimizing further aggressive interactions.

How to Stop Your Dog from Being Frightened

Having a fearful dog can be frustrating and heartbreaking. The key is to increase socialization at a slow, safe rate to allow them to get comfortable with changing environments. Forcing them into a frightening situation can make aggression worse. They need slow, consistent work to conquer their fears and should be positively rewarded for their progress. Desensitization training can help by slowly introducing scary items or noises and allowing them to grow accustomed. Fearful dogs need extra time to get used to new and scary things and should be given positive encouragement along the way. Professional trainers can be very helpful in creating a plan to help a fearful dog.