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Why Dogs That Live Together Start Getting Into Serious Fights

Dogs Fighting

Table of Contents

The Age Of The Dogs Can Be A Trigger

Adult Dog/Puppy Adolescent Dog

In most cases, all may appear to be well when one dog is in the puppy stage of life. There usually is (to a certain extent) a ‘restraint-governor/ in place when a puppy and an older dog live together. More so, though, on the older dogs. That doesn’t mean the older dog (as so many amateur dog trainers recommend to companion dog owners) will completely or always ignore inappropriate behavior from the puppy.

In general terms, though, the pup knows not to push too hard lest it triggers an adult’s wrath for which it cannot physically cope. However, starting when a dog hits about 18 months of age, they may decide that they ‘have what it takes’ to assert themselves. Depending on the nature of the other dog, there can be an escalation of more severe aggression.

Puppy/Puppy (Same age and similar breed.)

Often puppy owners are unfamiliar with how roughly dogs, regardless of age, play with each other. As a result, inexperienced companion dog owners misinterpret the play battles (complete with vocalization (growls, yelps, etc.) and nipping and mouthing and even biting) that are an instrumental and expected part of social development as being more severe than they are.

Even when, from time to time, these rough-housing sessions escalate into more severe spats, they are still perfectly normal, albeit often disturbing (to humans, and a lesser extent the pup on the receiving end) part of social development.

When interfered with too frequently, the pups fail to learn appropriate boundaries with each other, resolve issues, and there is a significant risk that left unresolved, there ends up being an escalation of the behavior.

Puppy Socialization/Kindergarten Classes - Puppy/Puppy (Various ages and dissimilar breeds.)

Puppy socialization classes have become a favorite income stream for amateur companion dog trainers. However, because the vast majority of amateur dog trainers and veterinarians are seemingly unaware of the extensive research (Scott and Fuller) regarding canine critical socialization periods, they recommend puppy ‘socialization’ classes and all too often do more harm than good. 

Canine behavior scientists Scott and Fuller’s research showed that the timing of socialization is critical. That it is a critical period is one reason why a companion puppy owner looking to form the most stable general temperament possible in their new puppy should avoid these classes. Generally speaking, they have more potential for downside than upside. For what it’s worth, they are also a red-flag that the person offering the classes is very likely an amateur.

A dog’s critical imprint period lasts from three to twelve weeks of age (plus or minus variation of one week). However, dog to dog social behavior/tone/body language imprinting occurs inside that period from three to six weeks of age. With this in mind, one must wonder about the most popularly used ‘selling’ feature for these classes. Even though these classes occur outside of the known canine imprint period, they are promoted as vehicles to ‘Socialize Your Dog.’

Ironically, as a result, puppy ‘socialization’ classes are far more likely to cause direct harm, and often indirect harm. The indirect damage occurs because concerning legitimately forming their puppy’s temperament, well-intentioned companion dog owners’ has, on the topic, their understanding and energies misdirected. Instead of using the actual critical imprint period to begin sensible carefully planned exposures to the sorts of things that contribute towards stability in temperament and avoidance of the development (due to lack or unintentional negative exposure) of fear and aggression in dogs, the average companion puppy owner is being led to believe, by the largely amateur dog training world, that visiting unfamiliar puppies once per week, for an hour, for a few weeks is ‘socialization.’ 

Forming a stable temperament in a dog involves good genetics, but a large influencer is the critical imprint period that includes graduated exposure to sounds, sights, smells, and textures. Additionally, exposure to things like exposure to children in different development stages, skateboards, motorcycles, and other odd-sounding and moving wheeled modes of transport, thunder, fireworks, traffic, etc. None of which will typically be found in a puppy “socialization” class)

Even veterinarians have been known to play a role in developing fearful and/or anxious temperaments in their client’s dogs, as they often tell puppy owners to keep their puppies away from temperament forming experiences until all vaccinations are complete. Using common-sense puppies can be protected and have their temperaments develop.

For many dogs attending a ‘puppy socialization class,’ there is a profound negative effect on their future quality of life. If you’re interested in learning more, you can read my book – Socialize Your Puppy for Everything – John Wade.

Puppies that go to these classes can, from a dog-to-dog context, come out with one of three perspectives:

  1. No notable impact on the dog to dog socialization as that period is well past and the beginnings of addiction to treats as a means for motivation.
  2. A fear that they may be bullied by dogs they are unfamiliar with.
  3. The belief that they can get away with bullying dogs they are unfamiliar with.

The Genetics Of Each Dog

Genetics - Breed

Some breeds are more Ferraris-like, and some others, more minivan-like. Ferraris breeds, while more challenging to drive and maintain, are typically extremely biddable. However, training and living with a Ferraris personality or breed can be more of a hobby than simple pet ownership. As you’ll read below, the method, degree, and maintenance of training can impact the behavior when living with more than one dog far more than when living with just one.

Genetics - Breeding

Physical and behavioral stability are characteristics that can be purposefully bred in or accidentally bred out of a breed. Unfortunately, most breeders, even when they are well-intentioned, or simply what I refer to as ‘Greeders’ or ‘Band-Wagon Breeders’, know little more than the difference between a male and a female dog. As a result, we see many dogs with lower thresholds for stress and biddability.

Breeders authentically looking to breed stable dogs must regularly contact puppy owners weekly until the imprint period passed, monthly up until adolescence, quarterly into adulthood, and annually afterward. They would ask questions about each dog bred to determine how well or poorly their breeding program was fairing.

A dog’s breed can have a lot to say as to Ferrari vs. minivan. Some bloodlines within a breed can be more intense in this department as well.

Owner-Dog Relationship Perception

How a dog perceives the person or persons they live with is one of the lesser known and ironically more common causes of aggression amongst dogs that live together.

Most people are never exposed to legitimate companion dog training (see below – Approach To Training). The treat, treat, treat, and approach tends to develop a ‘great roommates’ relationship rather than a loving authority figure. When one or more dogs are trained and live with their owners in a manner that they also learn to perceive their owners as loving authority figures, there is far less to fight about and over.

With some, if not most single dog households, when the dog perceives its owner as nothing more than a ‘great roommate,’ the downside isn’t necessarily going to culminate in serious aggression issues. More often than not, the dog grows up more driven by hormones and species/breed genetics and ends up being more a goofball that can at best do what the amateur dog training world calls obedience but are nothing more than tricks.

Waiting to see where one’s dog might mature in the ‘friendly goofball to gun with a brain’ spectrum isn’t the best idea when living with one dog. However, when living with two, the roommate approach opens the door to far more resource conflict. Learning how to live with and train multiple dogs more in keeping with nature’s template can go a long way towards removing ‘bones of contention’ between the dogs themselves.

Approach To Training (Methodology - Pseudo-Science Vs Science)

Companion dog training has historically been driven far more by groups of people who love dogs than legitimate applicable science.

As a result, very few companion dog puppy and dog owners are exposed to a useful life-skill training approach. Dogs grow up having at best learned a few ‘tricks’ (now called obedience in the amateur dog training world), and where it matters are far more driven by their hormones and species/breed genetics. The replacement of the ‘loving authority’ figure with the all-positive ‘roommate’ opens the door for at best a limited life-style and at worst a wide range of behavior problems, including dog to do aggression.

Dogs exposed to what is considered ‘training’ that end up with behavior problems are typically exposed instead to one or both of the following two highly flawed and effectively limited ideologies.

  1. ‘Might Is Right,’ Alpha, Pack Leader, Dominant (Yank and Crank)
  2. ‘All Positive/Purely Positive/Force-Free/Never Say No/R+…’, treat, treat, treat

‘Might Is Right,’ Alpha, Pack Leader, Dominant (Yank and Crank) training will impact behavior. However, more in the context of how a bouncer in a bar affects behavior than a loving authority figure. It should be avoided.

The ‘treat, treat, treat’ approach also impacts behavior but more in the context of a heroin addict/dealer relationship than a loving authority figure. This ‘here’s a $50 bill approach loses its efficacy when a $100 bill turns up, and for the average dog, those $100 bills take the form of squirrels, other dogs, guests, unfamiliar trespassers, etc. Also, should be avoided.

Of the two, it is the ‘All Positive/Purely Positive/Force-Free’ ideology that has become the most popular and is because of its popularity, (but more so because of its lack of efficacy in a real-world context) that is responsible for contributing to behavior problems such as dog to dog aggression inside the home.

How higher-order social species like dogs, wolves, apes, and humans teach and learn life-skills is very different from what amateur dog trainers believe and teach. No reasonable parent/loving authority figure uses brutality, bribery, or ignores ‘bad’ behavior to teach life-skills to their offspring.

Embracing the far more effective science-based relationship method to train a dog can often reverse the damage.

Learned Behavior

This section applies more so, but not always to dogs that are aggressive towards unfamiliar dogs, sometimes, only when they are leashed. However, it can contribute to ‘stacking’ a dog into a conditioned agitated when restrained, which can apply in dog-to-dog aggression inside the home scenarios.

Some dogs ‘accidentally’ become aggressive or more aggressive due to the lack of efficacy in the two training approaches mentioned earlier. When despite best efforts, a dog owner finds they are struggling with their dog’s behavior (typically by the time the dog reaches 18 months of age), training having failed, they often turn to mechanical means. They more often end up using it as an emergency brake when their dog is triggered instead of a tool contributing to learning to exert self-control.

The equipment kicks in with subtle and sometimes not so subtle physical pressure on the dog, which impacts its attitude precisely the same way one uses ‘agitation training’ to trigger aggression in a guard/police dog. In a less controlled intentioned setting, this can evolve into increased aggression and eventually conditioned aggression in time.

The flip side of the coin is the trainers that implement `Might Is Right’ recommendations. Dogs that are physically corrected in the presence of anything that agitates them are as likely to become more aggressive as to become less aggressive as to some, their fears are merely being confirmed.

Health Issues (Diagnosed Or Undiagnosed)

Dogs historically somewhat aggressive may become more so, and dogs without a history of aggression may become aggressive if they aren’t feeling well. Sometimes the aggression is a byproduct of not feeling well, and sometimes it’s an actual known symptom. Hypothyroidism is one example.

Alternatively, in a multi-dog household, a dog with a known or an unknown health issue may be targeted by the other dogs.

The Movie, The Lady And The Tramp, Was Not A Dog Behavior Documentary

Not all dogs, due to the nature, and, or nurture reasons outlined above are inclined to live with other dogs. With enough effort, it’s technically possible to force them to behave, but that’s not the same thing as enjoying living with other dogs and can be very stressful on one dog, or the other(s), and the owner. This article explains some of the factors a dog owner should consider before getting a second dog. Second Dog – Good Idea Or Not?

– John Wade 🐾


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