15 Types of Aggression in Dogs

Whether it's a door, a fence, or a leash, some dogs can't handle barriers if they're in the mood to get footloose or have discovered something they want that's on the other side of the obstacle. Barrier aggression can be intense and result in injuries if you're not careful. Even usually friendly dogs can explode.

There's a fancy term for this: iatrogenic aggression. In simple terms, it refers to the side effects of medication. Meds as innocuous as prednisone (prescribed for allergies or inflammation) can cause behavioral changes for the worse.

Some infectious and non-infectious diseases can cause aggression, too, with rabies being the most well-known.

This kind of aggression is linked to resource competition and can be directed toward the owner rather than strangers. If a dog learns that being assertive helps them achieve their objective, they will keep demonstrating offensive behavior.

This is not about hierarchy in a household but about getting what they want and avoiding what they dislike. Mature dogs over the age of two that behave confrontationally can put you on edge because submitting to them reinforces the behavior, and challenging them can result in injury and throws fear-based aggression into the mix.

Of course, some dogs are taught to be aggressive—this is nothing new. Dogs have guarded against intruders or kept enemies at bay for hundreds of years, and law enforcement agencies have trained police dogs for over a century.

But training a dog in this manner should not be taken lightly, and you should enlist a professional to be on the safe side. Bear in mind, also, that some dog breeds known for their aggression, like pitbulls, are banned by law in various states.

Fear-based aggression is especially a concern if you're rehoming a dog with an abusive past. Your new ward will react negatively to situations that remind them of previous trauma or punishment. And a lone bad experience with, say, a bald white man, could make your dog go bananas around bald white men.

Like humans, even dogs with seemingly no baggage can respond poorly to unfamiliar people and animals or anxiety-inducing circumstances. Scared dogs often retreat, but when there's nowhere to go, or they're in familiar territory, you might notice their body posture changing from fearful to hostile.

You don't want to get on the wrong side of a momma with babies to protect. Maternal aggression is a significant phenomenon in the animal world, including among humans. The most gentle woman can become unrecognizable if you threaten her offspring.

Even pseudopregnancies in female dogs can result in aggression around the time the puppies would have entered the world. Positive reinforcement with treats can coax a mother to leave her litter so you can tend to them.

Consider how moody some folks get when they're under the weather. The same applies to dogs—when they're sore or ill, they can become irritable. They also growl to protect themselves if they anticipate that physical contact will exacerbate the pain.

You may be aware of the source of the pain, or it may be, for example, an undiagnosed case of hereditary hip dysplasia. Pain-related aggression can appear out of the blue.

When puppies exhibit aggression towards human and non-human members of your household, it's normal, so you can stop worrying about whether you've got a little weirdo on your hands. For young dogs, everything is new, and they can't contain their excitement.

Your pup will give you pause when it wrecks your favorite sweater, accidentally leaves you with an injury, or nips other pets. It has to learn boundaries and your response to aggressive behavior needs to be measured to prevent future issues. In older canines, play aggression can occur at dog parks.

You'll also see this common type of aggression referred to as resource guarding. Siblings know about resource guarding all too well. Mom makes a dessert everyone loves, and you're sitting down with your share when you notice your brother swoop in to try and claim it. You see red.

Someone might not be approaching your dog to steal its prized possession, favorite chill-out spot, or preferred buddy, but it perceives a threat to its moment of joy and goes on the offensive.

Hunting instincts also fuel aggressive behavior. Your dog may, without much fanfare, stalk, chase, and launch itself at wild animals that visit your garden, or it might only display these behaviors when around other dogs, which is why some dog play areas separate large and small dogs.

Predatory aggression becomes problematic when Fido focuses on children and household pets, and you'll need to find workarounds ASAP.

Ritualized aggression takes place as a warning. Postures such as keeping the head and tail up, direct stares, and a frozen, never-gonna-back-down stance are all firm suggestions to back off if you don't want something worse to happen. This type of aggression is more about communication and avoiding conflict.

Pubescent humans are no strangers to sexual aggression, and neither are dogs. In the latter, this type of aggression typically refers to competition for mating partners and aggression toward rivals. Intrasexual aggression is also most common in dogs that haven't been spayed or neutered.

Your dog may not know how to play nice in social situations, so training becomes essential if early encounters at the dog park turn into the canine equivalent of Rocky sequels. Poor social skills may mean bullying or overreactions. Again, social aggression is observed more among dogs of the same sex.

This is similar to resource guarding, but unfamiliar individuals often get the brunt of territorial aggression. Your fur baby may bare its teeth and transform to snarl at people it perceives will hurt or take you away—you are its territory too, and it wants to protect you.

Early socialization helps to set the tone and normalize specific interactions. Well-trained watchdogs do their job by alerting you to activity but calm down when you need them to.

Borne of frustration, this type of aggression occurs when something rubs your dog the wrong way, but it can't get to the source of its emotional arousal and lashes out at someone or something else. Redirected bites can occur if you try to intervene when two dogs are fighting or if barrier aggression leads two dogs in the same household to attack each other.