Why Are Dogs Aggressive

DOG_HUMAN_AGGRESSION_FeaturedDefining what aggression means is not easy, because there are so many variables associated with what is a highly complex behavior. But by investigating the function served by an aggressive act as well as why it occurs and what result it achieves from the dog’s point of view, we can begin to gain a better understanding. At its core, aggressive behavior addresses the dog’s need to increase distance from a perceived danger and includes threat and action displays, ranging from a subtle lip lift to a deep bite. In most cases the intention is not so much to harm as it is to change the “threat’s” behavior by making it go away.

Aggression is deeply rooted in the dog’s instinctual need for safety. Growling, snapping, lunging, and biting are critical ways of communicating intent, and whether that intent is to warn, intimidate, resolve conflict, increase distance, defend, or cause harm, it’s designed to ensure personal safety and survival. Even on an emotional level, when a dog is fearful, frustrated, angry, anxious, stressed, or in pain, safety is of paramount importance. Most dogs don’t live their lives walking on eggshells, but the functional need for safety is intricately woven into most aspects of aggressive behavior.

Of course, there are those who explain all aggressive behavior in terms of dominance, but as we now know, using the “d word” to describe every dog’s intent can be misleading.  Because the term itself suggests a preconceived plan by the dog to use aggression as a means of establishing an elevated status over others, this fuels an owner’s anger and encourages a rank reduction protocol involving punishment, confrontation, and other unpleasant methods to establish an owner’s authority, which in turn increases the likelihood that the dog will aggress again in the future.

Although aggressive behavior is an effective way for dogs to control their environment, affect behavior in others, ensure priority access to resources, and achieve reproductive success, using the dog’s supposed desire to be the ‘alpha’  to explain why dogs aggress does not do justice to what is really going on in the dog’s mind.  A more accurate explanation lies in the fact that if a dog has not been taught how to function successfully in a domestic environment he will behave the only way he knows how. He may control access to food, space, furniture, or other things that provide comfort and pleasure, by aggressing, but this is more likely done out of fear that he will lose access to those resources and not because he wants to  be “above” everyone else in the household.

So if attaining the position of ‘alpha’ is not the root cause of domestic dogs’ aggressive behavior, what is?

Genetics, health, age, sex, fear, an imbalance of brain chemicals, hormones, and whether the dog is intact or neutered--all are factors that influence aggression. Studies show, for example, that due to higher testosterone levels, intact male dogs between eighteen months and two years of age have a greater incidence of aggression than females or neutered males. It is also important to point out that even though dogs can bite when in pain and because of other medical reasons, there are some cases of aggression that simply cannot be easily explained. These cases are categorized as idiopathic (unexplained) aggression, which manifests itself as a sudden explosion absent of any known trigger. Idiopathic aggression has been linked to chemical disturbances in the brain, such as canine epilepsy.

There is a clear link between anger, anxiety, and fear-based aggressive behavior. This has recently been demonstrated by Dr. Karen Overall of the Center for Neurobiology and Behavior at the University of Pennsylvania, who found that dogs with a history of aggression problems have levels of neurotransmitters and stress hormones similar to those of dogs that suffer from fear and anxiety. When a dog aggresses, he surpasses his stress threshold, causing his limbic system (the emotional brain) to take over as he prepares for flight or fight. When this occurs, the cerebral cortex (the learning brain) is inhibited, explaining why it is so hard to get a dog’s attention and encourage him to learn when he is reacting, as he is at that moment incapable of rational thought. To overcome this situation, a punitive trainer would try to suppress the aggressive outburst with punishment, whereas a positive trainer would immediately remove the dog from the stressor by quickly walking him away or creating some distraction to cut through the reaction. Only when the dog is in a calmer state can he begin to learn again. The secret to successfully treating aggression is to never put your dog in a situation where he goes over his stress threshold. Achieving this requires sensitive, compassionate handling and the manipulation of his environment to set him up for success while working on ways to change the way he feels about a particular stressor.

Unfortunately, we cannot sit down with our dogs and ask them how they feel, but we can observe them closely to understand why they feel. Helping an aggressive dog become more confident by teaching it to see a perceived threat or potential loss of a valued resource in a different light is the key to successfully changing the behavior. For some dogs this can be achieved in a relatively short period of time, but others require more time; each dog learns at a different pace. Positive reinforcement is the most effective philosophy to use in these cases, because the methods have a lasting impact, even on the “red zone” dogs.

Owners want quick fixes for their dog’s aggressive behavior because they worry about what damage their dog may do, but the “quick fix” idea demeans a dog’s emotional experience and is psychologically unachievable. When a dog is suffering from anxiety or fear, it is sheer foolishness to profess that he can be “fixed” quickly; this idea of “success” is dangerous and fundamentally wrong.

Imagine what would happen if people who suffered from chronic fear or attacks of anxiety went to their psychotherapists and were guaranteed they’d be “cured” in an hour, a day, or even a couple of weeks. Those therapists wouldn’t be in business for long. Successfully addressing fear and anxiety-related behaviors in both humans and dogs takes time, patience, and an understanding of what’s going on in the brain and body. It’s true that some positive behavioral modification processes take more time and work on the front end, but the result is a lifetime of positively changed behavior. Quick fixes may suppress the behavior at that moment, but because they don’t actually change it, you could spend a lifetime dealing with the problem

A dog needs time and support to change the way he feels emotionally; punitive training only puts a bandage on the problem without really addressing the cause and changing the way the dog feels inside. Even though it may look like the dog is “behaving” better, continual suppression of aggressive behavior through punishment is very dangerous because every incident creates another negative experience for a dog that is already a ticking time bomb waiting to explode.

Unlike other manifestations of aggressive behavior, predatory aggression is not emotionally driven and is largely influenced by genetics. Some dogs do find it reinforcing to chase other animals or moving objects as it fulfills an instinctive need but this is only the beginning of the predatory sequence. Humans have bred the desire to bite and kill out of the domestic dog, but occasionally a deeper instinct takes over. Although many dogs, including my Sadie, enjoy shaking and disemboweling stuffed toys, this sequence does not translate to live animals or people. Herding breeds are adept at eyeing, stalking, and chasing their “prey,” but they will seldom attack and kill the animals they are herding. Dogs that are motivated by the chase, grab, bite, and kill part of the sequence can be very dangerous to live with, especially around small animals and children.

Aggressive behavior serves many important functions for dogs; it is a deeply rooted natural instinct that ensures reproductive success, safety, and survival. If aggression is successful it can be an effective way to repel a perceived threat and to control resources, space, and environment. On an emotional level, aggression causes extreme stress for dogs, especially if triggered by a traumatic incidence, abusive handling, or an inability to cope with continually changing environments. Regardless of its origins or intent in the dog’s life, aggression is almost never a useful or wanted behavior in any domestic environment and must be treated appropriately in order to preserve the well-being of the dog, the environment, and his human family.

You can find more about aggression and workable solutions for aggressive behavior in my new book, Train Your Dog Positively.

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22 thoughts on “Why Are Dogs Aggressive

  1. Bonnie

    Some dogs are just dog aggressive by nature. I have an intact 15 1/2 year old champion Shiba Inu who has been male aggressive since he was about 10 months old. Shibas can be dog aggressive without there being anything "wrong" with them. Sometimes it is just the nature of the dog. This dog is well socialized, friendly with humans of all sizes shapes and ages and gets along well with female (unaltered) dogs. He doesn't need to be "fixed" - It is his nature. He's had a great life for 15 1/2 years without being put in a position of being loose with other intact males. He's become less aggressive as he's aged.

    Know your dog.

  2. Kim

    This is such a clear explanation of aggressive behavior. Thank you. I work with inmate handlers as part of a small dog rescue organization. I've started teaching them the neurobiology of basic behavior along with learning to "read" canine body language. It's a very natural pairing and the inmates have come to understand that stressed dogs are often not in need of correction but more likely need safety and distraction. Thank you for continuing to demonstrate that positive training creates dogs and humans in strong, bonded relationships.

  3. jacqui kearney



  4. Dina

    Please, put white backround behind thje text. This is sooooo hard to read! I had to copy the text and read it in Word. Great read though! Thanks.

  5. Chris

    I enjoyed reading "Why are dogs aggressive" blog, it has a lot of good information. Although, I have to respectively disagree with your statement, "Dogs that are motivated by the chase, grab, bite, and kill part of the sequence can be very dangerous to live with, especially around small animals and children." I have two retired racing greyhounds who are very motivated by the chase, grab, bite and kill part of the sequence. Even though I try to take precautions to keep the local wildlife safe, they have killed a few rabbits in our yard. I would never own rabbits or other small mammals such as gerbils or mice as long as I have greyhounds, but my dogs behave well around cats, toy dog breeds and children. I know that is not always the case. I have also known some greyhounds with a high prey drive who could not safely be around cats or toy dog breeds, but were ok around children. I do think that some animals, for example some wolf hybrids, individuals who have a very high prey drive, may not be able to live safely with small animals and children. I don't want to sound like I am picking on wolf hybrids, I was just using them as an example.

  6. Cheryl

    Hi I know your busy but I need help with my alaskian malamute puppy he's being very dominant and bitting a lot,it's at the point were he's making us bleed and putting holes in are clothes,when me and my husband say no he barks back or growls,also no one can eat there tea without him jumping up and barking or bitting because there eating,he's really good listening untill he's bored I fed him treats when he is being good and listening but I don't know what else to do please HELP

  7. Sylvia

    I have 2 Greyhounds adopted from the racetrack of Ireland. When I've got my second one Blue Ray, now 2,5 years ago I didn't expect that this boy would be a huge challenge for me. I learned him how to walk on a leash and much more. I found out that he wasn't easy to house training. Then he has bitten 4 little dogs and 1 big dog . He is extremely fast, I have him always on a short leash and it's like the speed of lightening that he can lunge to something he sees.
    I had asked a trainer but she couldn't help me. When he sees a small dog far away running around without a leash he stiffens and begin to focus on the dog. I lead him away or at least I try but he is as strong as a bear.
    Now for my own safety, my dogs safety and the safety of other dogs, I only walk him with a muzzle.

    Is there anything I ca do here please ?

    Thank you.

  8. Pat May

    Hello Victoria!

    I have been a fan of yours for years. I have a dog who is the very cutest ticking bomb. I shudder to think how many times he has attacked me. He's about 35 pounds, looks like a Tibetan Terrier mix, background unknown - other that from a kill shelter in KY. Age- guess 8 years old.

    His name is BO and I have had at least 4 trainers and spent hundreds of dollars trying to help him. I have 2 other dogs as well which he has never hurt any of them.

    BOO doesn't just bite - he attacks. At this points I have accepted his behavior and I always show care to not rattle his hot buttons.

    Overall he is a happy dog but he must have either a brain chemical imbalance or fear of something as he's been part of this family for over 3 years and things have never improved.

    Please help me find peace for this dog.

    Thank you.

    Pat May

  9. Tina

    I enjoyed your article about aggressive behavior. I am currently dealing with a aggressive dog. I am almost to the point of re homing him. We own 8 dogs. 7 Boston Terriers and a Pit Bull. The pit is spayed. Both female BT's are spayed. 2 of the male BT's are neutered. Ironically it is the neuters that are fighting! We can have all the dogs out together except for these 2. Only one of them with the others at a time. One or the other is sequestured and they take turns. If they even get near each other, there is a fight! SEVERE FIGHT!!!!!! I have tried positive training. I can not afford proffesional help. All I can so is keep the 2 of them apart. It breaks my heart. I am a firm believer in a pet is a lifetime commitment. I need help and do not kow where to turn!!

  10. Janene Branc

    Thank you, Victoria, for your eloquent and succinct explanation. This is what I too have been advocating for the past 8 years, in relation to aggressive and/or reactive dogs.
    I work a great deal with dogs that are reactive - they react to the environment they cannot cope in, and also with dogs that have been declared dangerous. The initial rehabilitation program is 6 weeks, however, for these dogs it is a life long management plan, with the emphasis on keeping the dogs under threshold. I must say it is a highly successful program, and the difference to the dog, the owner and their bond is outstanding.
    Keep spreading the word, Victoria - the power of positive training, and the understanding of WHY the dog is behaving in such a way. 🙂

  11. Darcy H. Heidt

    have a rescue schnauzer that has started to be aggressive and nipped me and is growling now daily.Help only had him for 4 months and he is about 11 months old!!!!

  12. Sandra Lee

    I have A 3 year old Blue Heeler I have raised him from birth I also have his mom the last two and a half months 2-3 months he has Ben getting very aggressive charge me And my old man I don't know what's causing his behavior he is growling out of the blue when you feed him he has grown twice when you just playing with him and when you hug him he has days when you can do all of the stuff that he is growing over he will snap at you when you go to feed him he has never had any of these aggressive attitude I don't know what is going on with him but I don't trust him around kids and I have a 8 year old that he belongs to and he has raised him from a baby and he has never Growl or anything towards us until now the first attempt sign was when he had Launch torch my old man second attempt I had went to go Feed him and he grow I discipline him told him no he does get his exercise everyday but still today alone he had growl at me when I when to give him A hug I need some help on this he is A wonderful baby boy

  13. Darcy H. Heidt

    I cannot do more exercise.am older woman and walk twice a day and run in my backyard when not raining.Not enough money for a lot of private training.thanks for the help keep writing,Darcy.......pulls on the leash although a choker and needs more socialization with other people and dogs,Help!!!!!who are you John?Are you with victoria?

  14. jane

    (Dogs that are motivated by the chase, grab, bite, and kill part of the
    sequence can be very dangerous to live with, especially around small
    animals and children.)

    Sorry but i don't think that's wholey true, i have a young lurcher who is very pray driven, so much so he would kill himself to chase, catch and kill small animals, but yet he's great around kids - couldn't care less if they run round and just sleeps.

  15. Smith2895

    first of all.... dogs hate hugs, he might have accepted it but he never liked it....
    if he just started behaving aggressive "out of the blue" to things that
    he has accepted before, take him to the vet for a health check, maybe
    he has some health problem or pain that is causing him to react...
    NEVER discipline him when he growls, but respect his wishes and give
    him space, growling is communicating with you asking for you to stop
    whatever you are doing and give him some space... punishing a dog for
    growling is like taking batteries out of the smoke alarm... he will
    learn that communicating does not work and might snap at you and bite
    you next time.

  16. Kathy Bull

    i have a 4 month old jack russell pup, he is quite fearful, the vet says he will grow out of it. he is not as bad as when i first got him but she does scare easy. he is nippy when excited, any advice?

  17. Meghan McCoy-Smith

    The dogs with the "deeper instinct" to bite and kill when over-stimulated...can these dogs be trained not to kill? My dogs have lived together peacefully for 3 1/2 years, but we've just moved to a place with a big back yard finally, and my big Am Staff has started to turn on our other dog, a Boxer half his size. How do I train him not to kill her?!!

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