Pet Boarding & Daycare

Defining the 5 Causes of Aggression

Defining the 5 Causes of Aggression

By Steven Appelbaum

Boarding and daycare facilities typically see a myriad of behavioral challenges from their canine guests.   Most are pesky and harmless; jumping up on people, excessive barking, whining, occasional chewing and a general lack of obedience are common examples.  Some dogs react to boarding and daycare by being overly rambunctious, while others can be withdrawn and shy.  Patience and kindness can work wonders in helping dogs stressed about being left by their owners to accept and even grow to enjoy their stays.  

One behavior that is more difficult and dangerous to deal with is aggression. Dogs become aggressive for a number of reasons. These include but are not limited to; fear, learned, pain, dominance and illness.  Understanding root causes is critical to treating any problem, as aggression is often a symptom of an underlying causative factor.  Let’s look at some of these.


When a dog is fearful, the most common reaction is for them to put distance between themselves and what scares them.  Dogs go through critical developmental periods at young ages, and experiences they have (or don’t have) during these times can be one of the reasons why they are fearful of certain things afterwards.  

The general socialization period ends at about 16 weeks.  If dogs don’t get around people during this time, or their involvement with human beings at this juncture are negative, they can be fearful or uneasy around people.  Some experience trauma during this time. Loud noises and negative encounters with objects or people can all cause problems when they get older. 

Fear of people is common with dogs that aren’t socialized properly.  As noted earlier, most dogs will simply move away from things that scare them, but a boarding or daycare situation is different.  In this environment, escape isn’t always easy.  When a dog tries to escape, and can’t, they can become aggressive. This type of behavior can be treated but it takes time and experience, and is not without some risk.


This one can cause confusion.  While occasionally I would work with dogs whose owners had deliberately taught them to be aggressive toward people, that’s not the most common type of learned aggression I saw.  The most common is simply a dog that has learned that aggressive behavior gets them a desired result.  

Let’s look at an example: A dog is fearful upon greeting new people.  She normally just runs away.  However, on several occasions, the owner put the dog on a leash prior to her meeting a guest and prevented her from escaping.  The guest approached the dog and, frantic, the dog snapped or lunged at the guest.  This caused the guest to cease their approach and back off, which was perfectly understandable. In this instance, the dog’s aggression stopped what the dog considered a threat. This means, from the dog’s point of view, the aggressive behavior was successful.  After a few times, most dogs reacting this way, will have learned that the best defense is a strong offense.  

Learned aggression is almost always connected to other root causes.  Fear being the most common. And sometimes owners would teach this behavior without realizing it.  


A dog’s reaction to pain will vary depending upon the dog.  Some will yelp and try to run away.  Others will cower and shut down—and others will become aggressive.  This kind of aggressive response is one of the many reasons why punishment-based training methods can be problematic.  Aside from the fact that using pain or the threat of pain as a motivation is simply not the best way to train, such methods can compound challenges by causing aggressive responses in the dogs who are being subjected to them.

Learned behavior often occurs in conjunction to pain elicited responses.  For example: A dog experiences rough handling at a grooming facility.  She reacts by snapping at the person who responds by backing off.  Perhaps this occurs at home as well.  Within a very short period of time, anyone touching the dog runs the risk of being growled at, snapped at or bitten.  Dogs like this can be worked with, but as noted throughout this article, it takes an expert and should not be undertaken without serious consideration of the real risks.


For many decades, people misunderstood this one. The thinking went like this: Dogs are descendants of wolves and wolves are territorial pack animals.  Within the pack there are leaders and followers, each fitting into a hierarchy.  The pack was ruled by the “Alpha” or “Top Dog” who generally enforced his/her rule by tooth and claw.  This theory was believed by countless generations of people familiar with such stories as Jack London’s “Call of the Wild.” 

Since dogs are related to wolves, the theory goes they must also be pack animals and need to be taught that their owners were Alpha.  Physical punishment and techniques like the “Alpha Roll Over”, where a person is supposed to grab the dog by the scuff of their neck and roll them into a submissive position on their backs, were created to mimic this supposed wolf-like behavior and assist the owner in establishing them as Top Dog.  The problem is that we have come to understand that neither dog nor wolf behavior is that black and white.  

There is an incredible array of subtle body cues, vocalizations and behavioral responses both dogs and wolves engage in when communicating with one another.  Physical punishment is a last resort as it runs the risk of injury and getting hurt in the wild can mean death.  What’s more, leadership positions in a group are sometimes fluid.  The bottom line is that old methods of establishing leadership or dominance using physical punishment have been largely abandoned—which is a good thing.   However, this doesn’t mean that some dogs don’t have assertive dominant personalities and that these dogs won’t be aggressive if a person tries to handle them in a way they don’t like.  Dominant aggressive dogs are a real thing and it takes an experienced trainer to work with them in a humane and effective fashion.  


We’ve all read this disclaimer a thousand times: “Check with a doctor before starting _____”.  All too often people ignore this advice.  It is best not to when it comes to ruling out any type of physical ailment that could be causing a dog’s aggressive behavior.  This is especially true if the dog appears to be lethargic, sick, in pain or unusually sensitive to being moved or touched.  I have seen and heard of countless cases of dogs whose aggressive behavior was stimulated by some sort of illness or injury the owners simply weren’t aware of.  

Aggressive behavior can be difficult to address without a great deal of specialized experience.  Facilities who are seriously considering allowing aggressive dogs to board with them need to work with a trainer or behavioral specialist who has done this before and comes with impeccable references. What’s more, you will need to make certain that only trained people come into contact with these dogs.  

Steven Appelbaum is a professional animal trainer and founder of Animal Behavior College (ABC), a vocational school specializing in animal career training programs.  ABC offers courses for people interested in becoming pet groomers, dog trainers, cat trainers, veterinary assistants and aquatics management specialists.  They will be introducing a zookeeper assistant program in 2019.  The school also teaches a variety of continuing education programs on subjects including; pet nutrition, pet massage, dog walking, pet sitting and training shelter dogs. Aside from managing ABC, Appelbaum works as a freelance author, lecturer and pet business consultant.  For more information about Animal Behavior College, please visit the website at