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Intra-Household Aggression

Updated: Mar 10

A German Shepherd and a hound sleep with their heads touching through a gate.
Shadow & Cyan cuddle through an x-pen barrier

Intra-household aggression refers to aggression between pets in the same household or part of the same family. This post will primarily focus on dog-dog aggression cases, but much of the same information applies to inter-species aggression.

Intra-household cases are one of the most emotionally taxing behavior journeys in which to engage. Family members are often hyper-vigilant at home and may find it hard to let their guard down.

They may feel guilty that their attention is now divided, resulting in less engagement with each pet.

Family members may delay or change travel plans or family visits or avoid having company at the house to lessen the risk of management failure. There may be conflict between family members due to the stress of the aggressive incidents or about how to move forward.

Family members may be traumatized from witnessing or breaking up dog fights. They may have sustained injuries breaking up the conflicts. They have likely seen the animals they love hurt one another, or one hurt the other, sometimes very severely. They may not understand why and feel quite out of control.

Two dogs in matching jackets focus on their handlers in a wooded setting
Conrad & Emerson at a training session with their parents.

Families working through intra-household aggression must have strong support for themselves. While some family and friends may not understand what they are going through (which can be incredibly isolating), others may be able to listen, empathize, and offer other forms of support.

Finding an individual and family counselor, or speaking with a veterinary social worker, can be incredibly helpful in maintaining their wellness. Folks may find support through social media or support groups.

Support can be practical as well. Bringing in a dog walker, using well-vetted daycare, or having one of the pets stay with a friend or boarding facility for the short term can offer much-needed relief to the humans in the household.

Accessibility to such resources will vary significantly from case to case. Co-morbid behavior concerns, financial constraints, and geographic location influence the available options.


Defining Success and Understanding the Options in an Intra-Household Aggression Case

Defining a successful outcome, and understanding the potential outcomes, is an integral part of any behavior modification plan, but especially so in an intra-household case.

A baby gate is pictured, and a break stick hangs on the wall
Management and safety tools include baby gates and break sticks

A behavior consultant or veterinarian can help the family to understand their options.

Options in behavior cases include:

  • Long-term management

  • Management and behavior therapy

  • Rehome one of the pets

  • Behavioral euthanasia

None of these choices are easy, nor are they made lightly. Only the family can decide what is right in their unique situation.

Understanding the variables affecting the situation can help a family to make an informed choice.


Variables to Consider in an Intra-Household Aggression Case

Please consider these eighteen variables when assessing an intra-household case. I'll talk briefly about each below.

Bite Levels

One of the first factors in assessing a case is considering the level of conflict in which the pets have engaged, historically.

Using the Cara Shannon Bite Hierarchy for injuries inflicted on dogs we can assign the injuries an objective rating that gives us information about the potential damage a dog is likely to do again in future incidents.

When considering this variable the lower the bite level, the better.

Frequency of Conflicts

A boxer plays with a puzzle toy while a french bulldog watches from behind a baby gate
Reese plays with a puzzle toy while Barry watches from his mat behind a baby gate

If the pets have repeatedly engaged in negative interactions with one another they have become well-practiced in that particular behavior, and the relationship between the pets further deteriorates.

Each incident may create further anxiety in one or both dogs, or in other members of the household not directly involved.

We may see household members begin to function in a state of chronic stress.

Variety of Conflicts

In some cases, there may be one clear trigger. The aggression may only happen in a certain environment or in the presence of a certain trigger. These situations tend to be easier to manage, and the behavior work may be less complex.

In a case with high variability, we see aggression occur in multiple environments, or spurred by multiple or very general triggers.

An intra-household case in which conflict occurs in multiple contexts is more difficult to manage and requires a more complex behavior plan.


While considering the variability of the conflicts, we might also ask how predictable they are.

It is not uncommon for aggressive behaviors to be experienced as "out of the blue" or "unpredictable". Most pet parents are not aware of the more subtle communication that occurs between dogs and may miss the warning signs of conflict.

A behavior professional can help families understand the function of the aggressive behavior (because like all behaviors aggression serves a function), and can teach the family how to notice the changes in body language and behavior that lead up to an aggressive event.

Sometimes, though it may still be difficult to predit when the dog will have a problem. For example, the behavior may be generalizing very quickly.

We may see the behavior evolve due to ongoing social development.

Or perhaps the triggers are very broad, or hard to recognize.

Some dogs may escalate in their arousal quite quickly, with few warning signs.

Sometimes the triggers are what is unpredictable - if a dog is triggered to aggression by loud noises it may be hard to predict when those will occur.


Two labs ride in the back of a car, separated by a divider and seat belted into either side of the car
Tillie and Molly's mom got creative with their safety set-up in the car

When we consider the ever-important topic of management it is important to be realistic about what is sustainable, and for how long.

The family must consider how long they can live with the initial management plan.

In many cases, I recommend that the pets be kept separated by a minimum of two barriers until we are able to assess the variables in the case and set up a more nuanced plan.

Our management plan may include continued separation with two layers of safety at all times, for now. This can be challenging to maintain.

Giving everyone their own space, within a small space, can be quite challenging while larger spaces with open floor plans can require creativity and problem-solving skills to manage.

Someone living alone may find it challenging to meet everyone's needs, while someone living with many people may find it difficult to keep everyone on the same page.

Frequent visitors, children in the home, dogs who routinely escape barriers, and other factors can increase the likelihood of a breakdown in management.

[Video ID: A divided Zoom screen. On one side are two French bulldogs in a training session in front of a sunny window. On the other side is the author of this post]

Some families may be able to have one of the dogs stay in another household in the short term.

They may be able to bring in practical support to ensure the dogs' needs are still met, even when the family's attention is spread thin.

In some cases - cases with high predictability, low variability, low bite levels, etc. - the dogs may not need to be separated all of the time.

Sometimes management is feasible for weeks or months, or potentially the life of the dogs, without causing undue stress. Every case is unique.

Based on the variables above we can determine the likelihood of a management failure and the associated risk - more on that below.

Size, Sex, Breed, Age of the Dogs

Six dogs of varying breeds and sizes wait to jump into the back of a van
Delilah, Spock, Cyan, Amore, Grace, and Dill wait to load into the car

Now we begin to look at the individual pets involved -

Size is a significant factor in our risk assessment.

It is inherently more dangerous to have a very large dog aggress against a tiny dog.

Even if the small dog is the aggressor, we must consider how a considerably larger dog might accidentally cause damage to a smaller dog in an arousing situation or defense of oneself.

Size may also play a role in manageability – smaller dogs may be safer to manage and break up, while larger dogs may be harder for family members to physically manage, and the risk for intervening people or bystanders may be higher.

The sex of the dogs is relevant, too. Same-sex pairings tend to be more difficult to resolve than opposite-sex pairings. Statistically peaking, female-female pairings have the lowest success rate.

The breed of each individual dog may also be relevant. Understanding what the dog was carefully bred to do may help us understand the function of aggressive behavior, or what appears to be aggressive behavior. Herding dogs are going to herd, and terriers tend towards a high prey drive, for example.

Finally, we must consider age. When one or more of the dogs involved are still developing we can expect to see changes in the midst of our behavior work.

Adolescence is already a tumultuous time. It is not uncommon to see anxiety or fear become much louder during these months.

This is a common time to see reactivity and resource guarding behaviors appear or escalate, which can lead to conflict between housemates.

[Video ID: A divided Zoom screen. On the right is the author wearing overalls and a beanie. On the left a person works with their husky/GSD mix on one side of an x-pen, while a happy beagle moves around on the other side of the barrier.]

As dogs move through social maturity we see even more social changes, as one might expect. Here we may see the dynamic between the dogs evolve further, and especially if the relationship is already strained, it may devolve into aggressive interactions.

experience pain or discomfort, even if the family is unaware (dogs are often in pain long before we identify them as painful), and be more protective of their personal space. Their hearing eyesight may be dulling, leaving them more susceptible to missed cues or easy startling.

Medical History

Aggressive behavior is often due at least in part to pain or discomfort in the body.

Medical history is especially relevant in any aggression case as it may speak to the function of the behavior directly, or it may decrease the dog's threshold for stress.

[Video ID: A French Bulldog and an English Bulldog take a parallel walk]

Pain, discomfort, or dysregulation in the body affect behavior and can cause a dog (or person!) to be more likely to aggress. Learn more about pain in dogs here.

In cases involving aggression the client's veterinarian should be involved, and in some cases, a veterinary behaviorist. Learn more about when to involve a VB here.

With any sudden onset of aggression or recent escalation in aggression, a vet visit should be the first and most immediate stop.

A veterinarian can help to identify physical problems within the body that will affect the dog's behavior and overall quality of life. This might involve a pain management plan for dogs experiencing chronic pain.

Working with a veterinarian or veterinary behaviorist, we can also identify possible side effects of the dog’s medication that may influence their behavior.

It may also be that behavior medication is indicated. One or more of the dogs may suffer from conditions such as Generalized Anxiety Disorder, Global Phobia, Noise Phobia, PTSD, Canine Cognitive Dysfunction, or other diagnosis related to their mental health which affects their behavior and their overall well-being.

We must support the individual dog in their wellness to support them in healthy relationships, coping skills, and self-regulation. Their individual well-being is imperative to living with a good quality of life and must be part of the behavior work.

Social History

A dog's individual social history can tell us what social skills the dog has available to them. We may also learn about preferences the dog has, and where they might struggle in dog-to-dog interactions.

[Video ID: A black lab engages with her handler and moves away from the yellow lab just on-screen.]

A strong, positive social history and the ability to read and respond appropriately to communication from another dog go a long way in repairing a relationship. Dogs who have less experience socially, or only negative experiences to draw on, may need additional help to learn these skills.

A dog's social world is shaped by their earlier experiences and genetic factors. A dog may lack exposure to other dogs during critical times or may have had negative encounters. Puppies who leave their mother and littermates too early miss out on critical time spent learning how to dog with other dogs. Genetic factors can also play a role, as do factors at play in-utero.

Previous History between the Pets

The relationship between the pets in question is especially relevant. A dog may be wonderful with all other dogs, but have conflict with the other dog with whom they live. Just like humans, dogs have a social spectrum. They might enjoy some dogs and not others, and their tolerance for various situations may vary.

We hope that the pets involved have a long and robust positive history with one another, but that is not always the case.

A history fraught with negative interactions or fragile tolerance leaves little on which to build a positive relationship.

Many behavior professionals suggest a slow introduction period when adding a new pet to the home.

Training History

If a dog is already used to engaging, learning, problem-solving, and being creative, they have a head start in learning life skills.

Additionally, a dog with a positive training background may already possess certain behaviors in its repertoire that we can use to manage the environment and upon which to build, such as relaxing on a mat.

A history of aversive training may contribute to anxiety or aggression, a dog’s state of learned helplessness or aversion to the other dog, specific areas, or the humans involved.

Learn more about the American Veterinary Society of Animal Behavior's position on behavior modification methodologies in regards to aggression (and all other training and behavior realms).

Risk Assessment

Aggression cannot be cured. It is functional, natural behavior. Instead, we address the underlying function of the aggressive behavior to make it less likely to occur in the future. This means that there is an inherent risk to living with an animal who behaves aggressively.

Using the variables mentioned above we can discuss the likelihood of a management breakdown and the likely fall-out. These considerations should be re-assessed along the family's journey.

Risk is assessed not only to the pets involved in the conflicts but to the rest of the household. Physical safety, as well as emotional and mental well-being, must be considered.

Risk to the community must also be assessed, though not as often in intra-household cases as in some others. In some cases, there may be risks to visitors, pet sitters, children visiting the home, elderly or disabled populations, or other pets in the community. In some cases, families may wish to learn about and consider their legal liability.

Family Ability to Read Body Language

Two dogs playing with one another
Spock and Laz engage in play behavior

By now it's likely clear what a huge impact intra-household aggression can have on a family.

Learning canine body language is a beautiful way for household members to be empowered again. A significant component of avoiding aggressive incidents is the humans’ ability to read and understand their pets’ body language. When the family can recognize the early warning signs of conflict or distress, they can better intervene before escalation occurs.

The good news is that while body language might not be a familiar language initially, it can be learned!

Family Participation

How present the family can be to the behavior therapy impacts the ability to affect change in the intra-household dynamic.

Many factors may inhibit a family member's participation.

Some family members may be very angry or fearful, and unwilling or unable to participate.

Other families may be hindered by the amount of time they have to dedicate; even management without behavior therapy can be incredibly time-consuming.

Family Resources

A boxer sniffs in the leaves, ignoring a black dog several yards away
Milo and Fynn practicing a dog-dog set-up

Intra-household aggression uses many resources including financial, emotional, and the ever-fleeting resource of time.

Strong social resources are a significant benefit to a family living with aggression in the home.

Financial resources may determine the level of practical support the family is able to access, as well as behavior and medical care.

Emotional Bank Account

Living in a household experiencing intra-household conflict is emotionally exhausting. Family members may feel depressed, hopeless, isolated, angry, frustrated, guilty, ashamed, and embarrassed.

Some people develop PTSD due to the aggression that has occurred.

It is important for family members to include their own emotional wellness in their behavior plan, and it is common for family members to prioritize their pets to the point of neglecting their own self-care. Seeking professional support such as a therapist can greatly increase the coping skills and emotional latitude a family member brings to the table.


Heavily-Weighted Variables

Some of these variables matter more than others, and the weight of each will vary from case to case. Prognosis is not as simple as tallying up a score.

As you might already suspect, there are some variables that are more pertinent than others.

[Video ID: The camera pans over a field with woods in the background. There are multiple people present, and two dogs several yards apart. One dog engages with her handler while another watches and takes treats.]

Situations that involve high-level bite history are much harder to navigate. Dogs who bite at a high level will not be accepted by an ethical rescue, and generally cannot be ethically rehomed (in my opinion). The assessed risk is often remarkably high. High-level bites (level four and higher) are uninhibited and cause significant damage.

A significant size difference between the dogs can significantly impact the decisions made in a case due to the associated risk.

In some situations, family members may disagree about how to proceed. Sometimes the family may favor one dog over the other. Some family members may carry resentment and anger towards the aggressor or the dog they see as the instigator. This conflict can significantly impact the success of the case.

When management is poor, we will see conflict reoccur. It is likely then to see an increase in frequency and intensity.

If the dogs have no positive social history with other dogs or the dog in question, this will significantly impact the case.

And finally, the risk to household members can be a deciding factor. Only the family can decide what level of risk is appropriate for them.

The exception to this is in cases where a vulnerable population such as children may be at risk, in which case, or in cases where the legal system has become involved.


Common Catalysts for Conflict in Intra-Household Cases

Many intra-household cases are triggered by change.

Change comes in the form of a new addition to the home, or a loss.

Change in the environment can trigger intra-household aggression.

[Video ID: The camera pans from a sleeping boxer in an arm chair to a resting bulldog on a dog bed. Both dogs are tethered.]

Change in the health or appearance of one of the pets, hormonal changes, and developmental changes can trigger escalated or new conflict.

Aggression can occur due to heightened arousal, bullying, or jealousy. Resource guarding behaviors are a common theme in intra-household aggression.

Aggressive incidents and conflict are more likely to occur in tight spaces (especially combined with arousal). Barriers may cause frustration which leads to aggressive behavior.


What to Do Next

If you are experiencing intra-household conflict, reach out for professional support right away from a behavior consultant and your veterinarian or a veterinary behaviorist.

You are invited to reach out to me through my website or to find a certified behavior consultant using iaabc,org

Until you are able to secure professional help, keep everyone safe by implementing a management plan.

Baby gates, leashes, closed doors, crates, and otherwise keeping the pets separated by at least two barriers helps to keep everyone safe while further help is sought.

Know that you are not alone, and that support is available.

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