Why does my dog play so aggressive with other dogs?

Interdog Aggression in Dogs

Inter-dog aggression, or aggressive behavior between dogs, occurs when a dog is overly aggressive toward dogs in the same household or unfamiliar dogs. This behavior is often considered normal, but some dogs can become excessively aggressive due to many factors.

Inter-dog aggression occurs much more frequently in non-neutered male dogs. Common signs usually start appearing when the dog reaches puberty (between six and nine months old) or becomes socially mature at 18 to 36 months. Generally, inter-dog aggression is more of a problem between dogs of the same gender.

Symptoms and Types of Aggression in Dogs

The most common symptoms of inter-dog aggression include growling, biting, lip lifting, snapping, and lunging toward another dog. These behaviors may be accompanied by fearful or submissive body postures and expressions such as crouching, tucking the tail under, licking the lips, and backing away.

Typically, before a severe inter-dog aggression incident in the same household occurs, more discreet signs of social control will become noticeable. One tactic a dog may use is staring and blocking the other dog’s entrance into a room. A specific condition sometimes triggers the aggression, even though the dogs normally get along well.

Causes of Aggression in Dogs

The causes of this condition vary. A dog may have become overly aggressive because of its past experiences, including abuse and neglect. For example, it may not have socialized with other dogs as a puppy, or it may have had a traumatic encounter with another dog. Dogs rescued from dog fighting operations also tend to exhibit inter-dog aggression more frequently. 

An owner's behavior may also influence a manifestation of the condition (e.g., if an owner shows compassion for a weaker dog by punishing the more dominant dog). Other reasons for aggression are fear, wanting to protect territory and social status, or a painful medical condition. 

Diagnosing Aggression in Dogs

There is no official procedure to diagnose inter-dog aggression. Some symptoms are very similar to canine “play” behavior and excited, non-aggressive arousal. Biochemistry, urine analysis, and other laboratory tests usually yield unremarkable results. But if any abnormalities are identified, they may help the veterinarian find an underlying cause for the aggression. 

If a neurological condition is suspected, advanced imaging, like CT or MRI scans, may be necessary to determine whether it is a central nervous system (CNS) disease, or to rule out other underlying neurological conditions.

How to Handle Dog Aggression

There is no real cure for inter-dog aggression. Instead, treatment is heavily focused on controlling the problem. Owners must learn how to avoid situations that encourage aggressive behavior in the dog, and to break up fights quickly and safely when they occur. In situations where aggressive behavior is more likely to occur (e.g., walks in the park), the dog must be kept away from potential victims and be under constant control. The owner may also want to train the dog to feel comfortable wearing a protective head halter and basket muzzle.

Training for Aggressive Dogs

Behavioral modification plays a crucial role in the treatment of aggression in dogs. Utilizing licensed, professional veterinary trainers is absolutely necessary. The aggressive dog is slowly conditioned to not fear or react to other dogs through a variety of positive reinforcement training techniques.

Unfortunately, some owners cannot control, train, or avoid situations of dog aggression. In these cases, options include re-homing the dog to a situation that better fits their personality. Some dogs may be deemed unsafe to be around other animals, as well as humans. In these cases, humane euthanasia may be the best way to assure everyone's safety and well-being.

There is no specific licensed medication used to treat inter-dog aggression. However, there are many behavioral medications that can help treat anxiety or hyperexcitability, such as Prozac, Xanax, trazodone, acepromazine, and gabapentin. Some of these drugs are used on a daily basis, while others are only used for situational events.

Successful treatment of inter-dog aggression is usually measured by the decrease in severity or frequency of incidents. In addition, the treatment recommendations need to be implemented over the entire life of the dog. Even if aggressive incidents are completely eliminated for a period of time, relapses may occur if the owner does not strictly adhere to the recommendations at all times. Owners with aggressive dogs need to work closely with veterinary behaviorists and veterinarians to meet treatment goals. It takes a lot of time and patience, but many dogs are capable of controlling inter-dog aggression and leading normal, happy lives.

Aggression towards other dogs is arguably the most common form of aggression shown by our canine companions.

It’s not uncommon for a dog to get aggressive toward an unknown dog, or other dogs in the home, because a dog often feels the need to protect her territory. But, there is a limit as to how aggressive or protective a dog should be.

If your dog shows excessive aggressive behavior towards other dogs, then she is putting herself in a position where she could either suffer or inflict a potentially fatal injury, and this could ultimately result in a lawsuit or animal control taking your pet away.

Not all dogs like the interaction and sociality of other dogs.  Some simply are dominant and don’t want to share their space and their life “goodies” including their family and home, while others are defensive, scared or shy.  I liken this to social anxiety disorder in people when people are almost phobic to be at a party or in a situation with large amounts of people. However, curing dog aggression toward other dogs is possible!

The problem is that most owners want their dogs to be social, and ignore the warning signs of dog aggression.  Although some dogs can be socialized and learn to appreciate the company of other dogs, in severe cases some dogs need to be taught how to control their feelings toward other dogs, while living as the only dog or pet in their environment.

Dog On Dog Aggression is a Serious Problem!

Some dogs are genetically preprogrammed to be dog aggressive; i.e. Greyhounds might view smaller faster running dogs as prey or the “bunnies” they were bred to hunt, and other breeds such as some of the larger terriers have been bred to fight other dogs, with plenty of natural aggressive behavior. Some dogs are even MORE aggressive ON LEASH than they would normally be off leash.

What to Do?

If you are having questions about your dog and his behaviors, take them seriously, don’t discount them and walk blindly into a possible deadly situation! Safety for your dog and other dogs is the most important facet of dog on dog aggression training.

Next remember that aggression incites aggression, so adding punishment and pain to the situation via painful training collars, and scary tactics such as alpha rolling, will only make things worse for your dog. Some dogs with dog aggression issues suffer from displacement biting (biting their owners) while being forcefully corrected.

Causes of Dog-to-Dog Aggression

There are several factors that can cause a dog to be aggressive toward other dogs. For instance, the dog may have been neglected or abused in the past. Or, she may never have been socialized with other dogs when she was a puppy.

In some cases, adult dogs that are rescued from dog fighting operations could have aggressive behavior toward other dogs, or she may have experienced a traumatic encounter with another dog in her youth. A painful medical condition could also account for the dog’s irritability.

Symptoms of Canine Aggression

The most common symptoms of canine aggression include growling, biting or snapping, lip lifting, staring, and lunging towards another dog or puppy. In some cases, an aggressive dog may exhibit fearful or submissive body postures and expressions such as crouching, tucking of the tail, and backing away.

Diagnosing Canine Aggression

If your dog or puppy is starting to become over-aggressive, then you should take her to the veterinarian to rule out any potential medical causes. The vet will perform a variety of lab tests, including a biochemistry blood profile and urinalysis.

Dealing With an Aggressive Dog

If MRI results come back negative, then a medical condition is not the cause of the aggression. In such a case, you will have to take your own steps to help reduce the risk of an attack.

Such measures include avoiding risky situations or walking in areas where other dogs congregate, and training your dog to be comfortable wearing a muzzle.

You should also take a stronger stance on training your dog to help improve her behavior in the home. For instance, you should train your dog to listen to verbal cues, like “sit” and “stay.”

Medications for Canine Aggression

There currently isn’t a medicinal cure for dog-dog aggression, unless of course the aggression is being caused by an underlying health condition that can be treated. If the aggression is being caused by anxiety or fear, a veterinarian may prescribe an antidepressant, a benzodiazepine, or a serotonin uptake inhibitor to help keep the dog in a calmer state.

Stop Your Dog's Aggression Toward Other Dogs:

First you must employ desensitization, trust, positive reinforcement and obedience training.  Second, your dog must be desensitized to the visual stimulus and reaction brought on by seeing another dog.  As you work together as a team, using positive reinforcement and rewarding your dog for appropriate behavior you will build a level of trust.

Knowing how to work with your dog or puppy and giving him the appropriate behavioral cues will give him something else to focus on in the presence of other dogs and animals.  It is important to keep your dog and other dogs safe at all times while you are working and to work at a speed your dog is comfortable with.

For dog aggression issues, it is best to take a dog’s age, health, temperament, and preferences into account, while coming up with appropriate solutions. Be calm and do not put continuous tension on the leash. Dogs are very sensitive to what their human is feeling.

My dog picks up on my emotions and reflects them, except with much more intensity. Sometimes, I am not even conscious of feeling nervous or stressed, but my dog notices it and starts to act up. Once I consciously calm myself down, his behavior also improves.

A common mistake when meeting other dogs is to tense up, and get fearful of what our dog may do. If we are afraid, our dog will pick up on that fearful energy, and that will likely trigger an aggressive reaction.

Be careful not to put undue or continuous tension on the leash. Also, do not pull the dog straight back, as that will likely cause a lunge forward response. To remove my dog, I pull him to the side and quickly walk him past the other dog.

When I see another dog, I usually just ignore him and move along. I have found that avoidance is most effective when I avert my eyes from both dog, as well as owner. I keep my eyes forward, and keep walking at a natural pace. In this way, my dog learns that when we see other dogs, we avoid rather than confront.

Be careful not to crowd our dog while walking. If he feels trapped between us and the other dog, he may think he has no choice but to react aggressively. Do not stand still while trying to tug our dog away. Move away, and he will come along with us. At the same time, we are creating space so that he will not feel trapped.

I do not let my dog obsess or stare intensely at other dogs. Sometimes, my Shiba Inu will drop into a stalking-down-position, stare, and wait for the other dog to pass. Some people think that he is such a good boy for doing a Down, when other dogs are coming toward him, but he is actually just waiting to pounce.

Do not allow this bad behavior, do not let your dog or puppy practice it, do not even let him think about it. Just move him along, and ignore. If the other dog is somehow blocking us (e.g. if the owner is unable to control his dog), then walk away in a different direction. Do not stare the other dog down and do not confront him, either through posture or by physically engaging him.

Create Space or Block the Other Dog

We can do this by moving across the road or into a driveway, and waiting for the other dog to pass. We may also move our dog or puppy behind a barrier, for example a car. If there are no barriers available, we can try blocking the dog’s view with our body.

Dog treats and trying to get his attention do not work at this point, because the other dog is too close, and my dog is no longer listening. The advantage of walking my dog briskly past the other dog, is that he has less time to stare. In addition, he cannot fully obsess, because he must partly focus on walking.

However, using barriers and blocking may work better for a fearful dog. Some trainers suggest turning and walking away when we see another dog, rather than passing him or waiting for him to pass. There are two problems with this method:

If we turn away, the other dog will be following us. This may cause some dogs to keep looking back, to make sure that the follower is not a threat. I have tried this, and indeed my Shiba keeps looking back.

If we keep turning away, we may meet other dogs and get boxed in; especially if there are many dogs in our neighborhood.

Create Neutral Experiences

I try to create as many neutral dog-to-dog meeting experiences as possible. If every time my dog sees another dog, we just pass by and nothing interesting happens, it will become a non-event.

Being consistent with neutral greetings will build our dog’s confidence. Through repetition, we are teaching him how to behave (just avoid and move along), and how not to behave (get over-excited, frustrated, lunge, and pull). He will be more calm because he is not waiting in anticipation of a highly charged encounter, either for play or for confrontation.

I try to set my dog up for success, and do not let him practice aggressive behaviors when meeting other dogs. The more he practices, the more aggressive he will be. If my dog becomes agitated during a walk, I try to end the outing as soon as possible. Once in this mode, his adrenaline levels will be high for a fair duration, and he will likely react aggressively to all the dogs that we meet.

In this state, he will no longer be capable of learning, and will only be practicing dog aggressive behaviors. Being consistent with neutral or positive greetings will build our dog’s confidence.

Protect Your Dog from Rude Dogs and Rude People

If people with weak energy stop and want to meet my dog, I ask them nicely to please move on, because my dog is easily excitable. It is fine and good to let a dog or puppy meet people with calm energy, but make sure to let them know how to best meet our dog. In particular, turn away when he jumps, no quick movements, and no petting from above.

Keep Greetings Short and Sweet

While greeting another dog, we want to positively interrupt our dog every so often, and get him to refocus on us. Do this as many times as necessary, so that our dog does not get over-excited, and lose control of himself.

If our dog is too obsessed to move away and is strongly standing his ground, then we have waited too long to initiate the interrupt. Positive interrupts are also useful for dealing with human greetings, and getting our dog away from a dirty or unsuitable area.

The key to successful positive interrupts is to catch a dog early, before he starts to obsess on another dog or object.

Use positive interrupts and keep encounters short.

Be Aware of Aggression Triggers

Some dogs, for example Spitz-type adult dogs, have a natural look that may appear dominant (ears up, hair out, tail up). This dominant look may instigate other dogs to respond in kind, and start posturing as well. Conflicts may occur, and if neither dog is willing to back down, this may lead to a dog fight.

If I am unsure about a dog greeting, I just move on. Better to be safe than sorry. Be aware that your dog’s natural look may trigger a reaction.

Desensitize Your Dog to Other Dogs

The problem with dog-to-dog aggression issues, is that in regular situations the “other dog” stimulus is too strong, and environment is too unstructured for any learning to occur. Often, our dog overloads quickly and becomes reactive, because the other dog is too close, is staring, is hyper, or is charging toward us.

In the desensitization process, we do training in a quiet, enclosed environment, and start with a very weak version of the problem stimulus. In terms of reactivity toward other dogs, we can use distance to weaken its effect.

In this way, we also weaken the strength of our dog’s reaction, so that he will be calm enough to listen and learn. This is necessary, to create opportunities where we can begin to teach our dog to be calm and relaxed, while in the presence of another dog.

I take my dog a far distance away, far enough away that he is still calm and able to listen to me. Then, I get his attention by calling his name. If he looks at me, I praise, and treat him for behaving well. Sometimes, I also ask him to do very simple commands, e.g. Sit.

I let my dog sit and watch if he is calm.

I let my dog sit and watch the other dog as long as he is calm, and willing to give me his attention when I ask for it. Once we are both comfortable with this, I move one step toward the other dog and repeat the Focus and Sit exercises above.

Do not move too close to the other dog, too quickly. If we move forward too fast, our dog may become reactive, and will no longer be able to give us his attention. At this point, I no-mark my dog (uh-oh) and move back a few steps. Once we are far enough away, I try to get his attention again. When he gives it to me, I stop, praise, and treat.

Note – for desensitization to be successful, we want to keep our dog below his instinct threshold as much as possible.

I always try to make sessions short, fun, and rewarding. This helps our dog associate other dogs with being calm, and with positive experiences. I make sure to stop before my dog shows any obsessive behavior, and long before he becomes aggressive. Once a dog becomes reactive or shows aggressive behavior, it is usually best to end the session soon after.

As we make progress, we can slowly increase the strength of the problem stimulus. For example, we may allow the target dog to start moving around, or we may allow him to play with his handler.

The desensitization process can be long and difficult. Dogs with lower instinct thresholds (the point at which they lose control and switch to instinct) will be harder to desensitize. However, consistent practice will also help to raise this threshold.

For desensitization to be successful, it is always important to keep our dog below his instinct threshold.

What to Expect from Dog-to-Dog Aggression Training

Do not expect too much, too quickly, from our dog. Make sure to treat and praise him very well, if he voluntarily engages in avoidance maneuvers, when there are other dogs around. This includes looking away from the direction of the other dog, smelling and exploring the environment, or looking at us for direction.

If we keep practicing desensitization exercises, and teach our dog how to behave with other dogs, he will improve. As he matures, he will become more confident, be less dog aggressive, and be more comfortable around new experiences.

Inter-Dog Aggression

This is when dogs within the same household become aggressive with one another.  This type of aggression is more common in intact male dogs but can also be seen in intact female dogs and even neutered dogs.

This behavior is often considered normal but scuffles and antagonistic behaviors among family dogs is not normal and needs to be carefully dealt with. Treating dogs with inter-dog aggression requires acknowledging there is a problem and being willing to make some changes.

Caught early enough and with the use of positive reinforcement the aggressor can be taught through behavior modification to allow the other dog or puppy to exist in the home.

The victim must always be protected, and something as simple as putting a bell on the aggressor can let the victim know where he is at all times.

With behavior modification and positive reinforcement training, even dog aggression towards other dogs can be treated successfully, it may be difficult and it may be a slow process, but it is possible! Aggression within the pack can happen under nearly any circumstance. When the pack leader isn’t present, there is the possibility to be some disorder within the pack.

The dogs could have some dysfunction within the pack, depending upon the situation in which they live and you lead their pack. If your dogs are peaceful with you around, but fight when you’re gone, it is likely out of respect for you as the pack leader. However, there can still be some contention and power struggles for determining the pack’s pecking order when you are not around.

Major Concerns of Dog-to-Dog Aggression

There are two main concerns I have noted as big causes during my 25 year career as a dog trainer.

1. Owners Who Inadvertently Cause Dog Aggression

Yes, it is true… you can actually be the CAUSE of your dog’s dog aggression. The first way you can cause this is a total lack of socialization and exposure while the dog was a puppy. Puppies need socialization and exposure. If you take your puppy home and lock him in the house for a year, chances are he will not know how to act and react when he sees another dog. Social skills are built early.

Imagine locking up your child and not letting them out of the house until they are about 12. They have literally never seen another child. Chances are this child would never be able to have “normal” relationships. You see, we learn social interaction from one another, and if we don’t have it when we are young, we don’t understand it. Dogs are the same.

You cannot teach your dog how to communicate and socialize with other dogs, and neither can your dog trainer; this has to be learned through interaction with other dogs! Please safely socialize your puppies.

Creating Reactivity

Owners often, inadvertently, create leash reactivity. The problem starts when owners don’t begin by teaching their dogs “leash manners.” For your dog to not pull on the leash, he must be given those skills and taught how to walk nicely.

But, instead, people slap a leash on their dog and take him out for a walk. When the dog sees another dog, he begins to pull.

The dog doesn’t understand why the owner is acting like this (he just wants to see and play with the other dog), but instead he is feeling pain, and sensing frustration and anger from his owner. The next time a dog comes into view, the owner pulls his leash tight and he goes through the same yelling and popping routine and the frantic, fearful feeling from his owner.

The dog, being a smart mammal, associates pain, frustration, fear, and owner frustration with the sight of another dog. But he is a problem solver, and decides if he shows an aggressive behavior display, he can keep that scary other dog away from himself and his owner. The dog lunges, and barks, and acts defensively.

The other dog owner promptly turns and takes his dog in the other direction; effectively teaching the first dog that aggression will keep other dogs away. In essence, the first dog has learned, with the help of his owner, that other dogs are bad and that aggression will keep them away. This dog also feels he is in charge of the situation, and it is his responsibility to keep you both safe.

It is sad because if this dog had just been taught how to walk on a leash without pulling and with distractions, this never would have happened!

2. Owners Who Ignore and Rationalize Aggression

Some dogs are just dog aggressive and naturally exhibit aggressive behavior. Interestingly, my current adult dog (a five-year-old Malinois) has NEVER liked other dogs. Even at six months, he had to be separated and monitored with my animals.

Some dogs just have aggression issues, and it has nothing to do with their owners, it can be genetic.

The problem comes when these dog owners ignore it or rationalize it. I will be honest with anyone. My dog doesn’t “like” other dogs.

In someone else’s hands, he would most likely be exhibiting severe dog aggressive behavior. However, I have the training knowledge and skill to keep his focus on me so that he can completely ignore other dogs. But many people write aggression off.

Just last week, in the veterinary clinic where I work, there was a 30-pound dog barking, snapping, and lunging at two other dogs in the waiting area. The owner was discussing how sweet her dog was, and how he loved other dogs. Now, this may have some validity in normal life, but I can assure you this was not true at this moment. The dog would have gladly bitten either dog.

Don’t Ignore the Signs

Don’t ignore the signs! If your dog is barking, lunging, and growling at other dogs, he is giving you information about how he feels about that dog at that moment. If your dog does this often, he is telling you how he feels about most or all dogs. Don’t ignore his information. Don’t push him to be “social.”

He won’t trust you as an owner if you force him to do something that makes him uncomfortable. And, you are leaving him with two options: Either to get over it, or to use his teeth to get his feelings across. It really isn’t the best idea to force an animal, whose language you don’t speak, to do something that makes it very uncomfortable. And, it is unfair!

Aim for Focus

Teach your dog to “socialize” by focusing on you! If your dog is paying attention to you, and he knows you won’t FORCE him to socialize, you both win! He has a coping mechanism, focus on you, and you have a dog with good behavior.

To help you do that, here's a GREAT game to try, that starts to teach your dog how to stop looking at other dog's, and turn his focus back on you.

For more games on fixing dog aggression, check out our ERT (Emotional Reconditioning Training) program for dogs.