Types of aggression | Dog aggression | Dealing with dog aggression | Euthanization

Note: I am not (nor do I anywhere on this site represent myself to be) a canine behavior counselor or trainer. If your dog, regardless of breed, exhibits aggression toward humans or uncontrollable aggression of any sort, you should seek a qualified professional canine behavior consultant or trainer for immediate assistance. Click here for my training page, which has information about finding a qualified professional behaviorist or trainer.

“Aggression” is a very misunderstood concept. It is a behavior that individual dogs, not entire breeds, exhibit to varying degrees. Additionally, aggression has a variety of causes, symptoms, and solutions. Many people become concerned when their dog attacks a small animal or another dog; they feel that their dog may eventually attack a human as well. To truly understand and manage aggressive behaviors, owners must realize that “aggression” is not a blanket behavior – it is a group of individual behaviors which are not always related and do not always have the same outcomes. A food aggressive dog will not necessarily chase small animals (prey aggression), and a dog-aggressive dog will not necessarily bite humans.

Aggression is a somewhat complicated behavior, and often it is wise to consult with a professional behavior counselor or trainer to get advice when dealing with aggression issues where a person might be bitten. The cost of professional help is much smaller than the costs associated with a dog bite, which can include loss of life or severe injury (for human or dog), medical bills, vet bills, and legal bills, as well as a significant emotional drain.

Types of Aggression

The number and types of aggression vary greatly depending on which behavior expert you talk to. The following are the most common types:

  • Dominance aggression – Dogs typically fight amongst themselves to determine rank in a pack. This aggression is seen most often in unneutered males, but unspayed females and altered dogs may also fight for dominance.
  • Fear aggression – Fear aggressive dogs bite or attack out of defense much faster than average. Their aggressive reaction is out of proportion to the supposed threat. They are generally lacking in self confidence. They may have had a bad experience with the specific frightening event or object previously.
  • Territorial or possessive aggression – Dogs are naturally territorial animals. They will defend what they perceive as their “territory” from other dogs, humans, and other animals. When most people hear “territorial”, they imagine a male dog peeing on everything in the backyard. However, territory is not limited to urine-marked areas. Dogs may also become territorial over certain play toys or sleeping areas.
  • Food aggression – Some dogs are extremely possessive of their food and can lash out toward animals or humans that approach them while eating or come too near their food bowl. Some behaviorists categorize food aggression as a subset of territorial / possessive aggression.
  • Maternal aggression – Female dogs with puppies can be extremely protective and may bite or attack strangers coming near the “den” where the litter is located.
  • Hormonal aggression – Intact dogs (dogs that are not spayed or neutered) are much more likely to exhibit aggressive behavior. Some of this may be related to maternal aggression and territorial aggression, but some of it has to do with hormones. Intact male dogs can become exceptionally aggressive around female dogs that are in heat. There are some documented cases of fatal dog attacks occurring when the victim comes between a male dog and a female dog in heat.
  • Prey aggression (prey drive) – Dogs are predators and will instinctively chase, catch, shake, and tear items that they consider prey. This most commonly includes small animals and birds. Dog toys are also, basically, prey objects. Some poorly socialized or untrained dogs may confuse small children with prey objects.
  • Health issues – Dogs which exhibit aggressive behaviors without an apparent cause may be in need of medical attention. Dogs that are sick or in pain can act aggressively. Several diseases, such as rabies, can cause aggressive behavior. Mental defects or brain tumors can also prompt aggression. A veterinarian should be consulted if a health-related cause is suspected, or if the aggression can not be explained.
  • Redirected aggression – Sometimes, a highly aroused, anxious, or excited dog may redirect their anxiety in the form of aggression toward an unrelated object, person, or animal. For instance, a dog that is trying to “get at” another dog through a fence may become frustrated and lash out instead toward a nearby person or object. This is why experts warn dog owners not to get in the middle of an unexpected dog fight; one or both of the dogs could redirect their aggression toward the human.
  • Dog aggression (DA) – Contrary to popular belief, dog-aggression is not limited to one or a few types of dogs. It can be seen in all breeds. Unlike other forms of aggression, which can be directed toward humans, dogs, and other animals, dog-aggression is a very specific form of aggression directed only toward other dogs.

Which type of aggression is it?

In some cases, it’s hard for owners to determine what kind of aggression their dog is exhibiting. Additionally, each form of aggression has different treatment options. Because of the complex nature of aggressive behavior, it is possible to make the behavior worse through improper handling or treatment. For these reasons, it is often best for a dog owner to consult with a qualified canine behavior counselor or trainer for assistance in managing their dog. Pit bull owners should seek a counselor or trainer who is especially experienced with and likes pit bulls.

Dog Aggression

Our discussion on this page will focus on dog-aggression, which is very common with all types of dogs, and is one of the easiest to manage. Aggression toward people is NOT typical dog behavior and should NOT be tolerated or encouraged. If your dog is aggressing toward humans, you must seek professional assistance immediately!

I would also like to stress that dog-aggression is not breed specific. I have seen many individual dogs, of breeds from Labradors to Greyhounds to Scottish Terriers, that have exhibited aggression toward other dogs. And yes, some of those dogs have killed other dogs. Dog-aggression is not limited to pit bulls, nor do all pit bulls have dog-aggression. Each and every dog must be considered and managed individually.

However, because this site is specifically meant to assist pit bulls and pit bull owners, I will discuss dog-aggression as it pertains to the proper management of pit bulls. It would be wholly inappropriate for me to overlook an issue that many pit bull owners, especially novices, have difficulty understanding. Readers should not take my focus on pit bulls to mean that only pit bulls are dog-aggressive, nor should they assume that all pit bulls are dog-aggressive.

Dog-aggression has a devastating fallout for pit bulls in particular. This trait prohibits many pit bulls from doing dog-related activities such as dog sports, search-and-rescue, therapy, pet parades, pet store visits, and more, simply because they cannot be around other dogs. Responsible owners keep their DA (dog-aggressive) dogs at home, away from other dogs and, as a consequence, out of public view. This allows misinformation and myths about pit bulls to spread rapidly. The pit bulls most commonly seen in the news are the ones causing trouble because their irresponsible owners don’t know what they’re doing.

Another side effect can be seen in the number of pit bulls who are homeless. Many new and inexperienced pit bull owners are caught completely by surprise when their adolescent pit bull develops dog-aggression. They do not realize that the behavior is normal and manageable, and are likely to banish the dog to the shelter as “defective” or have it euthanized. DA pit bulls that end up in the shelter usually don’t make it out alive; for most pit bulls, being sent to the shelter results in an automatic death sentence.

Dog-aggression typically develops between nine months of age and two years of age, but it is not unheard of for a dog to develop DA much earlier or later in life. Dog owners should always expect and prepare for dog aggression, regardless of their dog’s current behavior. Prevention is key for keeping DA at bay. Puppy owners should start socializing their puppy with other dogs as early as possible so their dog will learn the correct way to interact in canine society. This socialization is not guaranteed to prevent DA, but it can reduce the severity of DA.

Factors that increase the likelihood of DA:

  • Owning multiple dogs
  • Same sex pairing (two males or two females)
  • One or more unneutered / unspayed dogs
  • Pup removed from litter earlier than eight weeks old
  • Owning littermates
  • Failure to train or socialize
  • Encouraging dog to “stick up for itself”
  • Letting two dogs “work it out”
  • Dog reaching maturity (9 months to 2 years of age)

Things that pit bull owners can do to decrease the likelihood and/or severity of DA:

  • Own only one dog
  • Spay/neuter all dogs in household
  • Keep dogs separate when not able to watch them
  • Train and socialize from day one
  • Prevent aggressive behavior, no matter how minor
  • Engage in reward-based training

Dog aggression is not an absolute, either-or condition. Some dogs may only aggress towards certain types of dogs (i.e. male dogs, big dogs), while they will get along fine with other types of dogs (i.e. puppies, small dogs). The amount of aggression also varies depending on the individual; some dogs may go nuts at the mere glimpse of another dog, while some dogs get along nicely until play gets too rough and they lose self-control.

Dealing with Dog Aggression

Dogs with DA are not “faulty”—they are normal! DA is a manageable behavior, and such management should be considered a basic responsibility of dog ownership.

In the vast majority of cases, dog-aggression is manageable! You will often hear this saying in the pit bull community: “Never trust a pit bull not to fight.” In fact, it is a saying that should apply to all dogs and all dog owners. Keeping that mantra in mind, owners must use caution when their dog is around other dogs, and should never leave their dog unsupervised with other dogs—including housemates, no matter how well they get along.

DA should be managed based on the strength of DA exhibited by an individual dog.

Dogs with extreme, seemingly unmanageable dog aggression should absolutely be examined by both a veterinarian and a qualified canine behavior counselor to determine the cause of the aggression and evaluate options. Note: the behavior counselor should specialize in pit bulls and/or dog aggression. Some behavior counselors do not understand either one, and their diagnosis can be flat-out wrong, sometimes resulting in catastrophe. Dogs with extreme DA should be kept away from all other dogs whenever possible and muzzled, leashed, and under the control of a competent adult when in public—no exceptions.

Dogs with higher-than-normal levels of DA may quarrel or fight with housemates and strange dogs alike. Such dogs will require either 1) a single dog household, or 2) a crate-and-rotate routine. Outside of the home, a highly DA dog may require a muzzle to prevent accidental contact with, and injury to, strange dogs.

An average dog may be fine with housemates but aggressive toward strange dogs. When the owner is not home, dogs should be kenneled or crated individually in order to prevent unmonitored interactions with each other. When outside of the home, the dog should always be kept on leash, and interactions with strange dogs should probably be kept to a bare minimum.

Dogs with lower-than-normal levels of DA are easier to handle around strange dogs and may even be friendly toward most dogs but should still be watched and handled with caution. They may be willing to fight with sufficient provocation (i.e. attacked by strange dog, quarrel over toy or treat). Again, DA often gets worse after a dog has been in its first real fight, so prevention is important. Do not set a mildly DA dog up to fail. However, well-behaved dogs with low DA should be given every opportunity to show off in public, including attendance at pet parades, therapy work, dog sports, and so on.

Pit bulls with virtually no DA should be taken in public frequently and given the opportunity to shine in the public spotlight. They are the rare individuals who have the power to connect with a frightened and uneducated public without risk of an incident with another dog. These pit bulls should be involved in dog sports, therapy, search-and-rescue, and any other activity the owner and dog can handle. If the dog is willing, but the owner is neither interested in nor capable of doing this sort of thing, the owner should consider finding a competent person who can “borrow” the dog for handling in such events.

Novice pit bull owners often assume that because their pit bull puppy is friendly toward other dogs, it is not going to develop DA. This is an incorrect assumption. Almost all puppies and young dogs will be friendly with other dogs, but as they mature, they may become more aggressive. For some dogs, DA has a very abrupt onset that can take a dog owner by surprise. Dog owners should always be prepared, even if their dog seems to be best friends with other dogs.

Even if their dog seems to have virtually no DA, pit bull owners should always err on the side of caution.

A multiple-dog household can be a bit of a challenge, especially when one dog has a higher-than-normal level of DA. Dogs should always be crated or kenneled individually when owners are not around. They should never be left to roam the house or yard together, or kept in the same kennel. Remember: it is harder (and more expensive) to break up a fight and deal with the aftermath than it is to prevent a fight in the first place.

When is euthanization appropriate?

This question is always very hard to ask but needs to be addressed. Euthanization is sometimes necessary for the sake of the dog, the dog’s family, and the public. Dogs that exhibit aggression toward humans or extreme aggression toward other dogs or animals are the most likely candidates for euthanization. The dangers posed to humans and other animals by extreme aggression are not to be taken lightly. Dog bites can result in severe injury, mental trauma, and occasionally death. Pit bulls, because of their public reputation, must be held to a higher standard of behavior.

Before you make the decision to euthanize, always consult with a veterinarian and a behaviorist that specializes in aggressive behavior! The decision to euthanize should not be taken lightly and all other options must be weighed carefully.

Factors to consider before euthanization:


Some owners would rather pass their aggressive dog to another home than consider euthanization. Whether the dog can be rehomed depends on a variety of factors, including the strength and type of aggression and the competence of a new owner. Dogs with manageable aggression (manageable dog-aggression, certain types of other aggression) can be rehomed with a responsible, informed new owner who is willing and able to care for the dog properly, but finding such an owner is going to be exceedingly difficult. Dogs with unmanageable aggression, or dogs that have bitten or attacked a person, should never be rehomed.

More on rehoming: Finding a New Home for Your Dog

Quality of life

Owners should also consider the aggressive dog’s quality of life. Dogs with extreme or unmanageable aggression are often suffering mentally. The stress associated with constant conflict severely damages a dog’s quality of life. Euthanization may be a humane option for such tormented dogs.

Consult with experts

Before making the decision to euthanize, have the dog checked out by a veterinarian to determine whether the aggression is related to a health problem. Then, consult with a canine behavior counselor who specializes in aggressive behavior to decide whether the aggression can be modified or managed safely. Some dog owners simply aren’t familiar with dog behavior and may misinterpret innocent play as aggression; a canine behavior counselor can prevent the dog’s needless death in those cases by clarifying the dog’s behavior.

Taking the above factors into consideration, it is ultimately the dog owner’s decision whether or not to euthanize. Although it is preferable to try to manage the aggression, in some cases it is simply not safe or healthy to do so. The advice of a professional is strongly recommended to help in making such a serious decision. The safety of the dog’s family and the public should always be paramount.

Related links:

Managing multi-dog households
Crate and Rotate
Leashes and Dog Parks
Training, socializing, and managing

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