Ask The Experts: Understanding Dog Aggression

Does your dog have aggressive tendencies? I’m talking about growling, biting, and attacking other dogs or humans. 

Do you feel like you’ve tried everything to change your dog’s behavior and nothing is working?

Are you frustrated because you just don’t understand why your dog “goes off” during certain situations, posing a risk to both your dog and others? 

You’re not alone. 

Sit Happens Dog Behavior TrainingI cannot tell you how many dog moms have approached me, asking about dog aggression. I hear the same story over and over and I understand how this issue can leave you feeling helpless. That’s why I reached out to Kathy Reilly, a Certified Dog Behavior Consultant just outside of Charlotte, North Carolina. Kathy began her career in basic dog training more than a decade ago. Since earning her diploma in Canine Behavior Science and Technology, she has dedicated her practice (Sit Happens) to clients dealing with high levels of aggression, anxiety, fear, or stress in their dogs. 

In this Q&A with Kathy, she explains what aggressive behavior stems from and offers tips to keep your pooch calmer and happier!

Q: Why are some dogs aggressive? 

A: The first thing to understand is that aggression is a natural response to a threat. It stems from fear. Most experts define aggression from a dog as “behavior(s) used to increase distance from and/or eliminate a threat.” The basic responses toward a threat are flight, fight, submission, or acceptance. Aggression falls under the fight response.

Second, there is no such thing as an “aggressive dog.” No dog walks around exhibiting aggressive behaviors 24/7/365.  Aggression is always a response to something in the dog’s environment, a trigger, whether it is the action of a human, the sudden appearance of another dog, pain caused by injury or illness, etc.

Third, aggression is instinctual and cannot be trained away. I like to explain to my clients that my reaction to being frightened is very different from my husband’s. If my kids jump out from behind a corner and scare me, my hands go up to my face, I hunch my shoulders in (basically making myself small) and I may scream. Afterwards, I laugh because I enjoy that rush of adrenaline. My husband, on the other hand, throws his fist out in a punch, makes himself bigger and is angry for quite a while afterwards. These instinctual reactions will not change. The kids can jump out at us over and over and our reactions will diminish due to desensitization to that particular threat for a period of time. But the next time we are truly scared, we will resort to our instinctual behaviors. 

As for why some dogs are aggressive and not others, scientists are still exploring that. They would like to find an “aggression gene” that they can look for and determine if a dog will be aggressive before you breed or adopt it. However, they are finding that it all comes down to the nature vs nurture argument. And with dogs, as it is with humans, we find it is a combination of both. If one or both parents were aggressive instinctually, a few of the pups will be aggressive. But not all of them. Alternatively, puppies from two non-reactive parents can become aggressive if not raised and socialized properly.

Q: What are some warning signs of dog aggression? 

A: Dogs won’t bite when a growl will do, meaning they don’t want to engage in a full on bite. It takes up a lot of valuable resources, energy, to do so. So they like to give warnings. Several things to look for as a precursor to a bite:

  1. Stiffening, tense body
  2. growling
  3. backing away, looking away, moving away
  4. lowering head
  5. cowering
  6. lunging
  7. yawning
  8. lip licking
  9. baring teeth
  10. slowing movements
  11. ears pinned back
  12. lips pulled tight
  13. hair raised along it’s back

It’s important to not punish a dog for growling and to let your dog move away if necessary. If you take away the growl or the ability to escape, he may have to bite to get the threat to go away. A growl is a good thing. It’s your dog’s way of saying, “Hey, I’m not comfortable and I really need you to back away.” Also, don’t punish a dog for displaying aggressive behaviors, as we now know they stem from fear and are instinctual. By getting angry and punishing your dog, you will be adding to his fear and anxiety.

Q: Is there a common age when dogs begin to develop aggression tendencies or are they born with them? 

A: There are several very important stages in a dog’s life. The first is the Socialization period – typically from 6-14 weeks of age. During this time, the synapses in the dog’s brain are growing a thousand fold. It is very important to expose your dog to many different people, places, animals, and things as possible during this time. Unfortunately, most veterinarians tell their clients not to take their puppies out anywhere until they have finished their vaccinations, which is usually well past this Socialization period. Your puppy should meet many people of different ages, colors, dress, etc. And the puppy should walk on many different surfaces and see many different places and environments. Now, we don’t want to frighten or overwhelm your puppy. These outings should be a positive experience.

Another important time is the Fear Period from 6 – 14 months. During this time, your dog is going through adolescence. It is important during this time to make sure your dog does not have any negative experiences with other dogs or people. I recommend organizing play groups with dogs you know your dog likes. Do not go to dog parks where one unruly, rude dog can change your dog forever. Do not force your dog into social situations with people or dogs that make him nervous. Be patient and gentle during this phase. It’s best to keep a normal routine during this time and monitor your dog for any signs of stress.

Q: Are some breeds more prone to aggressive behavior or can any dog become aggressive? 

A: Breed does not determine aggressiveness. Although some breeds have been bred to react aggressively to certain triggers, each dog must be evaluated individually, due to the nature vs nurture conflict we talked about above. A dog whose parents were bred to be aggressive to strangers, may never resort to the aggressive behaviors if socialized properly during the important stages of development and raised in a loving home with no punishment, but positive reinforcement and bond based training techniques. On the other hand, a dog with very sociable, nonreactive parents can become aggressive if not socialized properly or treated poorly with punishment and pain.

Q: What should I do if my dog becomes aggressive toward another dog (whether it be another dog in the house or a dog they just met at the park)

A: The first thing to do is to remember that this is your dog’s natural response to a threat. Your dog is frightened. Frightened dogs want two things: time and distance. So, immediately create distance between your dog and the trigger. Don’t yell at or punish your dog. Instead, move away from the trigger and calm your dog. Let your dog observe the trigger from a distance and decide on his own if he wants to investigate it or just go away from it.

If the behavior continues, find a force free trainer in your area to help you learn to change your dog’s association with that trigger. You can find a trainer in your area at

Q: What should I do if my dog becomes aggressive toward me or another human? 

A: As we have discussed, aggression stems from fear of a threat. If your dog growls, lunges or bites you or another person, try to figure out what the trigger was that made the dog feel threatened. Remove your dog from the situation and find a force free trainer in your area. You can search for one at

Q: Are you supposed to punish an aggressive dog? If not, what should you do?

A: If you punish your dog for being aggressive, you will only be adding to his fear and anxiety. Your dog is not doing this to be “dominant” or to embarrass you. Your dog feels threatened and feels he needs to aggress in order to remove the threat and feel safe again. The best thing to do is to remove your dog from the situation, calmly and without anger. Then try to figure out what the dog may have seen as a threat and help your dog to avoid that threat in the future.

Q: Is there a way to “fix” aggressive behavior/ “cure” aggression? 

A: As I mentioned above, aggression cannot be trained away or fixed. It is an instinctual behavior performed automatically by some dogs in response to a threat. What you can do is learn your dog’s triggers (threats). Avoid exposing him to the threats. Work on changing his mind about particular triggers by associating something good with the something scary. In other words, if your dog is afraid of the mailman, try dropping yummy treats as soon as the mailman comes into view and don’t stop until the mailman is gone. With each practice, you will see your dog react less and less. This is because you have changed the association with the mailman. He is no longer a threat but a predictor of yummy treats. Over time, you will need fewer and fewer treats because your dog no longer fears the mailman.

Dog treat

Q: When is it time to seek professional help?

A: If your dog is hurting himself, another animal or person, it is time to seek help. If your dog’s quality of life or yours has diminished, it is time to seek help. If you are frightened of your dog, it is time to seek help. I strongly suggest you find a force free trainer, as any punishment or aversive techniques will not help your dog and may make things worse. The Pet Professional Guild is a force free association and can help you find a trainer near you.

Q: Anything else you want to mention about aggression that you think would be helpful for dog parents? 

A: Many people think that by giving treats to an aggressing dog, you will be rewarding the aggression. But remember, aggression is instinctual. Like a sneeze. You sneeze in response to a tickle in your nose. If I slapped you every time you sneezed, it would not stop you from sneezing. Likewise, if I offered you $100 to sneeze right now, you couldn’t, because it is an automatic response to a tickle in your nose.

Also, there is a very good scientific reason why we use treats to change behavior in dogs. 90% of the dogs’ brain is dedicated to smell. They even have scent glands in the back of their throat. When your dog is fearful or anxious, and you put something smelly in front of his nose, like a hotdog, you will switch which side of the brain is active. The fearful side will quiet down while the smell and taste side will light up. Both sides cannot be active at the same time. The more you continue to associate the trigger or threat with yummy smelly treats, the less threatening the trigger becomes. You have changed the association in the dog’s brain. (PS – if your dog is not food motivated, use a favorite toy or game to switch the brain from fear and aggression to fun and play).

Have More Aggression Questions?

Check out Kathy’s website – Sit Happens Behavior Consulting

Photo by: Sit Happens

Photo by: Sit Happens