12 Causes Of Aggression In Boxers (And What To Do About It)

Aggression is not usually a problem in Boxers, at least no moreso than with any other breed.

This doesn’t mean all Boxers are guaranteed to be automatically placid in every situation.

Boxers were originally bred as fighting, hunting and guard dogs and so they have within their DNA the capacity to be aggressive.

As with any dog, whether or not an individual Boxer displays aggressive behavior will depend upon a complex interaction of nature and nurture including:

  1. Breeding
  2. Dominance
  3. Socialization mistakes/Fear
  4. Poor management
  5. Past experiences
  6. Training
  7. Gender
  8. Neutering
  9. Health status
  10. Exercise
  11. Age
  12. Situational dynamics

I am not a vet. This article is intended for educational and general informational purposes. I encourage readers to view my full disclaimer. Boxer Dog Diaries is reader supported. I may receive a small commission, at no extra cost to you, if you make a purchase via links I share.

In order to avoid and manage any aggressive tendencies in your Boxer, it’s important to understand the various causes.

We’ll examine all 12 factors one by one.

But first — 

Are Boxer Dogs Considered An Aggressive Breed?

Boxers are known and loved for their sweet nature and their sense of humor.

But they contain multitudes.

It serves neither dog nor owner to pretend that aggression is not part of the Boxer temperament.

Aggression is the most commonly reported category of behavior problem in the domestic dog, and no breed is immune.

When Boxers were first developed in Germany, they were developed from a line of dogs that had been bred for hunting.

They were initially used in bull and bear baiting and then for many years were known primarily as guard dogs.

Boxers that come from European lines may have more aggressive tendencies than American Boxers.

(Despite this, European Boxers are generally more calm, focused, driven and may be more trainable.)

Any aggression in Boxers will typically take the form of attacking other dogs.

Boxers are fearless and will not shy from a fight.

Whether or not an individual Boxer instigates fights comes down to training and socialization.

The particular dynamics of each situation play a big part.

You will almost never see a Boxer display aggression towards people.

Types Of Aggression In Boxers

Not all aggression is inappropriate.

You may expect your Boxer to guard your home with force.

You may want him to have what it takes to intervene if there’s an intruder or when a family member is threatened.

You may even want him to be able to defend himself if attacked.

What you don’t want is your Boxer:

  • Picking fights at the dog park (whether or not the dog park is a good place to be with your Boxer is a separate conversation)
  • Showing any kind of aggression towards people who are not a threat
  • Having bad judgment about what represents a threat, or
  • Disregarding your commands once aggression has been triggered.

There are other forms of aggression that, to a degree, are a natural canine instinct but which need to be carefully managed such as:

  • Food aggression and/or resource guarding
  • Territoriality

Causes Of Boxer Dog Aggression

1. Breeding

Historically speaking, aggression is a component of the Boxer dog temperament, as discussed above.

However, modern Boxers are no longer bred as guards, hunters or fighters.

Though classified by the American Kennel Club as a working breed, Boxers are now kept primarily as companion animals.

They consistently rank as one of the most popular breeds kept as family pets throughout the United States.

Boxers sourced from breeders who prioritize temperament in their selection of breeding stock will still be Boxers with all their genetic lineage, but they will not be prone to inappropriate aggression.

Boxer puppies removed from the litter too early (eight to ten weeks is ideal) miss out on learning how to properly read social signals from other dogs, which may manifest as behavior problems later on.

This is also the period when pups are taught bite inhibition from their mothers and siblings.

Without the benefit of this training, pups can become overly “mouthy” in their new homes, where owners will complain of nipping and overly aggressive play.

Equally, it’s not advisable for pups to remain too long (beyond 12 weeks) with their litters, as their dominant or submissive positions in the pecking order can become ingrained.

2. Dominance

It’s best to select a puppy that is neither the most dominant nor the most submissive of the litter.

Bringing home the “pack leader” may mean you’re in for some power struggles as he grows up.

A middle-of-the-road littermate will be easier to train and more inclined to settle easily into the role of good “follower” dog.

Even a non-dominant Boxer will be strong willed with a healthy independent streak.

No Boxer will hesitate to act on his own, a trait that can make controlling aggression difficult.

A Boxer owner needs to provide strong leadership, clearly establishing him or herself a the “alpha” by being consistent, kind, calm, fair and in control at all times.

If the relationship between dog and owner is weak or ill-defined, problems including aggression can flow from there.

Work daily on building that relationship with plenty of play and training for the duration of your Boxer’s life.

3. Socialization Mistakes / Fear

Some aggression stems from fear or anxiety.

Exposing your Boxer to a wide range of social situations from an early age (and continuing to give him experience in new environments throughout adulthood) will make for a well-adjusted dog that feels confident and at ease in new and unfamiliar settings.

If you rescued your Boxer as an adult, it may take time to undo fear-based aggression that has been instilled in his previous home.

One or more aspects of your Boxer’s socialization may have been lacking, leaving him with hang-ups.

Perhaps your pup’s early socialization was interrupted by a period of confinement due to illness or COVID lockdowns.

It’s important to understand that, to a certain extent, aggression towards other dogs is an instinctual part of being a dog, hard-wired into the canine brain.

In the wild, wolf packs occupy and defend territories and don’t mix with dogs from other packs.

They will growl and bare their teeth at trespassing wolves, though this rarely escalates into actual fighting.

Actually, wolves are at pains to avoid crossing paths and do all they can to head off full-blown conflict.

As pets, we require dogs to interact with members of other packs (the pack being the family unit or household).

To do so without conflict they must override this natural instinct.

Doggy daycare and off-leash dog parks are two of the most glaring examples and represent settings that are ripe for conflict between dogs.

In addition, any situation where two or more dogs from the same household are interacting with non-belonging dogs ups the chances that pack dynamics will be activated.

4. Poor Management

Everything you do within the household sends a message to your dog about where he fits in the pecking order.

Boxers are expert readers of their humans and won’t miss any cues, whether or not you’re meaning to send them.

They’ll also quickly exploit any loopholes, so be consistent: make the rules and stick to them.

If your dog is showing sign of aggression, you may have to reconsider the house rules.

You can reinforce that your dog is lower in the pack by:

  • Feeding him after others have eaten
  • Ensuring he waits for humans to go through doors first
  • Not allowing him on furniture (if he’s at the same level as you, that tells him he’s of the same status)
  • Not allowing your Boxer in your bed (dogs interpret sleeping together as a sign of equality, like you’re littermates rather than pack leader and follower)
  • Having a “nothing for free” policy — this is a Susan Garrett training method whereby your dog must “ask permission” for everything eg. sitting for dinner

(We highly recommend Susan Garrett’s books including Ruff Love: A Relationship Building Program for You and Your Dog.)

Food aggression can be managed by feeding dogs separately and teaching your dog to accept food being taken away, then returned.

It’s a good idea to routinely reach into your dog’s bowl while he’s eating as a puppy, even taking food away and then putting it back.

The same with bones.

This way, your dog learns that you are in charge and that he doesn’t have to worry because the food will be returned.

5. Past Experiences

Often a Boxer that displays aggression towards other dogs will have had a negative experience with other dogs in his past.

Perhaps he was attacked once as a puppy.

This poses a challenge.

It will take time and concerted effort to reprogram your Boxer.

The goal is to replace fear and distrust and a pattern of aggressive encounters with positive, harmonious interactions.

More on how to approach this below.

In the rare instances where aggression in a Boxer is directed at people, you may need to engage a trainer experienced with the breed.

In adopted Boxers, aggression towards humans is doubtless related to previous negative encounters.

It can’t be tolerated, but over time, with the establishment of trust and the provision of clear, constant leadership, you should be able to overcome the problem.

6. Training

Don’t expect too much of your Boxer.

They are smart and can learn whatever you teach — but you do need to teach it.

In fact, you can’t avoid teaching your Boxer, because he’s learning every minute of the day.

By providing no guidance you are just teaching your dog that anything goes.

He will be only too glad to make up his own rules.

Show your dog what’s expected and then given him lots of structured opportunities to practice the skill.

If it’s a recall or “Come” command you’re teaching, work first in quiet areas.

Build up to working in closer and closer proximity to distractions as your dog’s confidence and ability grows.

With Boxers you need to keep training sessions short and FUN.

Avoid too much repetition and never give harsh corrections or physical punishment.

As long as it feels like a game, you’ll have your Boxer’s undivided attention.

Get rough or angry and he’ll shut down.

7. Gender

Boxers, like all dogs, are more likely to have physical confrontations with members of the same sex.

However, there are exceptions.

Always test new combinations of dogs, with close supervision.

Conflicts over toys or bones can erupt between any dogs.

Dog behavior is complex and much of what passes between dogs will be beneath the level of human awareness.

8. Neutering

The presence or absence of the sex organs affects a dog’s tendency for aggression in complex ways, sometimes creating the opposite effect to what you might expect.

Whenever a dog shows aggressive tendencies, many owners look to neutering as a solution.

To a certain extent, neutering may make a dog more docile.

People who keep Boxers as working dogs, for instance, report that they keep them intact because neutering reduces a dog’s spunk and drive in an overall sense.

In this way, a neutered dog may be more “chilled out”.

However, the equation is not quite that simple.

Removing a dog’s hormone-producing sex organs — particularly when it’s done before adulthood which isn’t reached until the age of 2 or 3 in Boxers — is known to increase the incidence of behavioral problems that run the gamut from anxiety, fear of storms and noise phobias to unwanted sexual behaviors and aggression.

Entire males smell different to neutered ones and can elicit aggressive reactions from other males purely based on that scent.

Intact females sometimes experience behavioral changes including crankiness when they go into heat.

This is not an argument in favor of neutering/spaying, which is known to increase the incidence of a large number of diseases including mast cell tumors.

Keeping your Boxer intact just creates some issues, all of which are manageable with a little planning and forethought.

9. Health Status

If a dog is sick or in pain he is more likely to feel afraid, unable to defend himself and therefore may lash out where he otherwise wouldn’t.

Some health problems, such as hypothyroidism, can cause aggression in dogs.

Commonly prescribed medication like the steroid prednisone is known to cause psychiatric disturbances in both dogs and people.

Dogs that have previously shown no aggression whatsoever can become aggressive when on prednisone, particularly when it’s high dose or long term.

This is what happened to the author’s 18-month-old Boxer Shiva on prednisone.

Boxer puppy eats raw meal

10. Exercise

A tired Boxer is a well behaved Boxer.

A Boxer with pent-up frustration and not receiving enough attention, mental stimulation or physical exercise will be more prone to inappropriate outbursts of energy, including in the form of aggression.

Need ideas for how to entertain your Boxer? Here are our Top 10 Best Toys For Boxer Dogs.

…And our Ten Worst Toys For Boxers which are just as important to know.

Games and tricks are are great way to keep your Boxer’s mind occupied in a constructive way.

11. Age

Owners are often shocked when their previously mild mannered Boxers suddenly show signs of aggression.

More often than not the dog is reaching adulthood.

At this point, dogs can begin to vie for dominance in the “pack”.

This is frequently what’s going on when Boxers in multi-dog households suddenly start to clash.

Intact dogs of the same sex, particularly males, can begin to perceive each other as “reproductive threats”, adding to the tension.

If you have raised two puppies at the same time, “littermate syndrome” may be at play.

This phenomenon can affect even non-siblings.

It’s why professional dog trainers advise against getting two pups within six months of each other.

Other signs of littermate syndrome include:

  • Co-dependence
  • High anxiety when separated
  • Failure to bond with the human family, and
  • One puppy becoming shy and withdrawn while the other is bold but nervous when alone.

If your very young Boxer puppy is growling occasionally, this may not be aggression-related.

Here is more information about what it might mean, and how to respond, if your eight to 14 week old Boxer pup is growling at you.

(Hint: It’s probably not true aggression.)

12. Situational Dynamics

This is one of the most powerful influences on whether a dog shows aggression.

A good amount of aggression in Boxers is situational.

It’s not a bad dog, but a good dog put in a bad situation.

A Boxer can be perfectly reliable in certain situations but almost guaranteed to show aggression in others.

Your Boxer might be gentle to a fault with dogs smaller than himself — even if those dogs are themselves aggressive — but triggered by dogs his own size or larger.

Maybe your Boxer is fine when he encounters dogs running free but feels trapped when on leash.

Or he might have a reaction to a certain breed of dog for reasons that escape you.

You may notice he’s fine with one-on-one interactions but three dogs is a recipe for disaster.

The first step is to know your Boxer.

Closely observe his behavior in a variety of scenarios with different kinds of dogs.

Be honest with yourself about your dog’s behavior, as well as your ability (or inability) to control it and know which situations carry a heightened risk.

Do your best to understand your dog’s triggers.

As with most things to do with our dogs, you may be more to blame than you’d like to think.

Did you always pick up your dog as a puppy whenever a larger dog came near?

Did you tense up when certain breeds approached?

You may have transferred your anxieties to your Boxer when he was small and now he’s large enough to fight back.

The good news is you also hold the solution in your hands.

How Do I Stop My Boxer Attacking Other Dogs?

If your Boxer has become reactive or is showing aggression towards other dogs, you need to put a stop to it — and fast.

A dangerous Boxer is a liability to himself and his owner as well as a threat to other dogs and people.

It can feel overwhelming, but aggression in Boxers is preventable, and reversible — though the latter is considerably more difficult.

Break it down into steps:

  1. Understand which situations carry a higher risk for your dog
  2. Take appropriate preventive steps to manage the risk, and
  3. Devise a plan for training more appropriate behavior.

Point 1 was addressed above so we’ll focus on steps 2 and 3.

Take Preventive Steps

In the immediate term, even before you’ve worked out how to fix things, you need a circuit breaker.

Stop putting your dog in situations you know are high-risk.

While your dog may start the fights, it’s only a matter of time before he happens upon an opponent that’s genuinely fierce.

Injuries from dog fights can be horrendous.

Change where you exercise your dog if need be, or go at a time of day when you can get space to yourselves.

If the confrontations occur when your dog is off leash, keep him on leash for now.

This won’t be forever.

Train More Appropriate Behavior

To un-train undesirable behaviors, you’ve got to go back to square one.

Step one is denying your Boxer the chance to rehearse and further ingrain the aggressive behaviors.

Then it’s a matter of working on engagement so your dog’s focus is on you, not other dogs.

An effective way of dealing with reactivity to other dogs is to use a clicker to condition your dog to look away whenever he spots another dog.

If he’s focused on you, he can’t react to another dog.

The Look Away Technique

To teach this you will need a clicker and a treat pouch.

Make sure you get a clicker with a wrist strap, like the Starmark Pro-Training Deluxe Clicker.

The Navaris Silicone Dog Treat Pouch clips on your belt and comes easily clean in warm soapy water.

Here are the steps:

  1. Stock a treat pouch with some small bites your dog loves and will do anything for
  2. Find a location where your dog will be able to see dogs passing by on leash from far enough away that he will not be reactive, and with a limited field of view. In a laneway is perfect, so that your dog has some distance and can only see the dogs for maybe five to ten seconds as they walk by. Do not attempt this exercise anywhere that dogs will be off-leash and able to approach your dog as it will undermine the whole lesson
  3. When a dog walks into view and your dog sees it, wait 2 seconds to give your dog a chance to look at you of his own volition. If he doesn’t, say “Focus” and when he looks at you, click and immediately give him a treat
  4. If your dog can’t look away from the dog, move further back from the passing dogs and try again. Keep moving back until you reach a distance at which he can concentrate enough to deliver the desired behavior. You can test if you’re at the right distance by seeing if your dog is relaxed enough to comply with a “Sit” command and to take a treat
  5. Practice, practice, practice, repeating this process many times for short periods on many different days and in a variety of locations
  6. After enough repetitions, your dog will start to look away from the dog without you having to prompt him by saying “Focus”. When he does this, click as usual and deliver a “jackpot” of rewards ie. several treats in a row, to mark that he’s done something fabulous. This is why you wait a couple of seconds after each dog comes into view so that your dog has the chance to offer the behavior of his own accord
  7. Once your dog is consistently looking away of his own accord when he spots a dog, move a little closer to the dogs and go again
  8. Eventually your dog will be so conditioned to look away from other dogs that he will do it without you telling him to, even when he’s right on the path where the dogs are walking. This is success and you are well on your way to getting your dog’s aggression/reactivity under control
  9. You can move on, adapting the same technique to any situation where your dog encounters other dogs, like when walking on a path and spotting a dog coming head-on towards him

In this video professional dog trainer and Dog Gone Problems founder David Codr demontrates the clicker-based look-away technique:

Another incompatible behavior you can use to distract your Boxer from other dogs is a tight heel while maintaining eye contact with you.

You will most likely need to use high-value treats as rewards.

Wear a treat pouch so your hands are free for controlling your dog.

If your dog isn’t very food-motivated, play can be used as a reward for Boxers.

Bring on walks a tug toy or bite rag like the Redline K9 Leather Puppy Bite Rag with Handle and use mini-tug sessions in place of treats for good behavior.

The idea is to reassert yourself as the most interesting thing in your dog’s world, and the source of the fun.

Once you have your dog’s attention in low-stress situations away from other dogs, and he’s recognizing you’re the boss, you’re ready to move on.

The final step is to gradually reexpose your Boxer to interactions with other dogs in a controlled way, so that he has the chance to practice new, appropriate behaviors in these social situations.

A long line like the 32 foot NIMBLE Waterproof Dog Leash Durable PVC Rope will be an invaluable tool during this process.

It gives your Boxer the freedom to make decisions while you retain control and the ability to give corrections.

Ultimately, if you are not having success in modifying your Boxer’s aggressive behavior, it may be time to engage a professional dog behaviorist.

Find a trainer experienced with Boxers and who uses positive reinforcement methods.


The causes of aggression in Boxers are multifactorial.

If your Boxer is showing aggression, chances are there are quite a few different things contributing to the problem.

Resetting each of them will be important in retraining your dog’s behavior.

It’s essential you do, not just for the safety of other dogs and owners, but to protect yourself, your family and your Boxer.

Dogs that attack other dogs or people are liable to be taken away and destroyed and their owners slapped with lawsuits.


Coren, Stanley PhD, Neutering Causes Behavior Problems in Male Dogs, Canine Corner, Psychology Today, May 9 2018

Hart, B; Hart, LA and Bain, MJ, Aggression toward people. Canine and feline behavior therapy. (2nd Ed.), Ames (IA), Blackwell Publishing. PP: 103-28, 2006

Littermate Syndrome Treatment Plan, Canine Behavioral Services Inc

Manteca, Xavier BVSc et al, Difficulties in The Diagnosis of Dominance Aggression in Dogs, WSAVA Congress, 2002

Range and Territory, Wolf Haven International, Tenino, Washington

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