As any ethologist or experienced dog trainer, will readily admit, that of all subjects relating to canine behaviour, aggression in dogs is the most difficult, not only to understand, but to correct. This is especially true in the case of relatively mature pooches, for as most experienced trainers know, a dog’s character is developed during the experiences of its life which it encounters within the first 5 phases of puppyhood.  IE between 4-6 months.  So, in short, for dogs that have already shown aggressive tendencies by the time they are 6 months of age, it becomes very difficult to reverse this. Not without significant patience and a well structured desensitisation training plan.

I have been asked to try to explain aggression as simply and in as few words as possible. This I can not do for the following reasons:- Aggression in dogs is a very complex phenomenon, and more than one motivation or trigger can be present during the same act of aggression today, yet because of one almost imperceptible difference in the circumstantial mix, have a totally different outcome tomorrow.

I have decided therefore to try to simplify things by recalling some of the content of an old lecture by Prof JSJ Odendaal, Dept of Ethology at Onderstepoort, almost 3 decades ago.  In my view, it is the easiest way to understand the complexities of the subject.  I shall briefly list and make a short comment on all 20 generally accepted factors which affect levels of aggression in dogs.

There are two Main motivations or triggers in a domestic dog for aggressive behaviour. The first one is:-

GENETIC INFLUENCES: These are broken down into three sub headings, namely A. Instinct Behaviour, B. Human Genetic Selection and C. Abnormal Behaviour.

A:    Instinct Behaviour is itself broken down into 11 of the 20 factors:

  1. Leadership: In any pack of dogs, one will emerge as the leader. Remember, that to a dog all human members of a family are just other members of the pack. Since this position is based on dominant-submissive behaviour, the choice of leader is often determined through aggression. Not too serious within a group of puppies, but more so between strange adult dogs.  Battles are normally, but not always, fought between males. Whenever a dog is placed in any home, it must never be permitted to become the leader of the family. Mature males of large breeds are particularly inclined to challenge for leadership.
  2. Pack Hierarchy: There will also be a dominance submission hierarchy amongst the other members of the pack where members are classified in order from the Alpha dog to the Omega. From time to time, aggression will occur in pursuit of a higher position in the pack. The lower order dog should not be protected. If he is, challenges will continue to escalate till resolved.
  3. Territorial Protection: Dogs, having evolved from Canis Lupus and Canis Ferus are territorial, and will instinctively try to protect their territory. This includes their property and their people, or other pack members. Protective aggression can benefit humans but if enhanced and practiced irresponsibly, without appropriate controls it can become a problem.  “alarming” behaviour like barking, or growling, forms part of this type of aggression.
  4. Maternal Instincts: People (especially kids) usually make big fuss of puppies and underestimate or forget about the type of aggressive response that may occur. Always remember, puppies should be handled very carefully in the mother’s presence.
  5. The Hunting Instinct: This is also known as the large dog/small dog syndrome. Larger dogs sometimes hunt smaller animals and many breeds are genetically designed to do so. Some believe that this hunting instinct, often latent till triggered by an event, may also be responsible for attacks on young kids or babies. This instinct is stronger in some breeds than in others.
  6. Anxiety: It is a common phenomenon for a dog to bite when anxious. This behaviour forms part of the fight or flight behaviour when a dog feels threatened, or when his safe space is invaded. Destructive behaviour in the absence of the owner, is often also associated with this separation type of anxiety. Strange dogs, being forced to meet/ interact whilst on leads and unable to escape, will often become more aggressive to each other, than if they were off lead.
  7. Pain: Pain related aggression is another common phenomenon, even towards its own family who are merely trying to help. When fighting dogs are beaten, their levels of aggression are stimulated even further, because of the pain that is inflicted.
  8. Competition: Dogs often show competition aggression, the most common one being for the food bowl. It may also involve sleeping quarters, a toy, a bone, or the owner’s attention. We humans interpret the latter as jealousy. It is very important never to place a child in a competitive situation with a dog, especially a big one.
  9. Discipline: This type of aggression is rarely mentioned in literature. If a puppy bothers an adult dog, especially a male, the dog will show aggression in order to discipline the puppy. It may only be a growl or single bite, but some pups have been killed in this way. This type of aggression may also explain why some adult dogs attack small children who annoy them.
  10. Play: When dogs play with one another or with people, the game may become so exciting that it changes into playful or serious aggression. Certain games will more easily develop into aggression than others, for eg tug rope games.
  11. Gender: 90% of problems related to leadership/dominance aggression, involve male dogs. Generally speaking, a bitch is more suitable for an urban family if aggression is an issue.
  12. Human Genetic Selection. Concerns only one important factor of the 20.
  13.    Fighting/Baiting Breeds:  For hundreds of years, special selective breeding programmes have resulted in aggression becoming a much desired preferential characteristic of certain breeds. Although this type of aggression is genetically based, it is the result of human intervention in the breeding of such animals, and humans must therefore take full responsibility for such aggression. It is often latent, just waiting to be triggered. Such breeds, normally referred to as bull or power breeds, were used for bull/bear baiting, and dog fighting, in the days when such activities were common place.  Whilst the breeds survived, mainly due to their aggressive macho looks which many still like, their activities however didn’t, and became outlawed.  However, the genetic predisposition for aggression remains, and to this day, can be subconsciously triggered by a variety of innate stimuli.
  14.               Abnormal Behaviour.  Concerns Idiopathic behaviour also covers one factor only.
  15.     Idiopathic aggression:  This type of aggression should be regarded illogical, inexplicable         and unexpected. The causes are not clear, so just like we see in some humans, we get some rare cases of crazy/psycho behaviour. Some could even be a health related issue or a brain dysfunction. The jury is still out.  But, in short, it is abnormal and fortunately its incidence is quite low.

          The second of the two Main motivations or triggers in a domestic dog for aggressive behaviour are:-

         THE ENVIRONMENTAL INFLUENCES: These are also broken down into three sub headings, namely: A.    The Conditioning Processes, B. The Physiological Processes and C. Displaced Behaviour.  

  1. The Conditioning Process, is itself broken down into 3 of the 20 factors:-


  1. Operant Acquired Conditioning. When young dogs are bullied for example, they may learn to be aggressive to cope. Neglected dogs who have to fight for survival also quickly learn to be aggressive.


  1. Socialisation. Lack of socialisation with people and or other dogs whilst growing up, may result in aggressive behaviour. Dogs who grow up amongst people, in the absence of other dogs may develop aggression towards other dogs. And of course those dogs that have little or no contact with other people during their younger life, may become distrustful of humans. The same can apply to a lack of interaction between dogs and children or human males or females. This is sometimes called group specific aggression. But the bottom line is that it is lack of socialisation.


  1. Training. Some dogs are taught to be aggressive for security and protection purposes. Trained professionally, these dogs usually only respond aggressively on human command and/or to certain triggers in a specific environment.  But trained poorly by amateurs, or ignorant owners who find it amusing to try to encourage aggression in their pets, yet have no appreciation of the possible consequences of their actions. Such dogs can act unpredictably.
  2. The Physiological Processes, are also broken down into three of the 20 factors:- 
  3.   Old Age.   Dogs like humans often become grumpy and snappy when they get old. In dogs, it can be ascribed to insecurity, stemming from their weakened senses and aching joints.    
  4.    Disease.   Underlying disease, chronic illness or health issues like a toothache for e.g., can make a dog aggressive. Such dogs do not want to be bothered and show aggression to protect themselves.
  5. Metabolic Disorders. Hunger, due to low blood sugar and hormonal changes may also give rise   to aggression.
  6. Displaced Behaviour. Is the last of the 20 generally accepted factors.

        20    Abnormal/Displaced behaviour.  Sometimes, two or more dogs belonging to the same owner will rush towards a strange dog behind a closed gate or other barrier. Being unable to get at the other dog, they will inexplicably start fighting amongst each other, or even a child nearby.  In such cases, their territorial protective aggression is “displaced” and superseded by mutual frustration related aggression. There was one such known case recently in South Africa.


For those who have managed to get to the end of this article, it will have become abundantly clear, that every case we hear of regarding dog aggression, needs to be analysed carefully. This can usually only be done by those people who know the dog and its history very well.  Sadly however, few such folk have the background or knowledge to do this, so they tend to jump to the wrong conclusions. So too, do the ignorant media and many others in the wake of a serious incident of dog aggression.  But hopefully, after reading this, one may at least be able to get a bit closer to putting ones finger on the right trigger/s.  An experienced ethologist may be able to help by asking all the right questions.



So, having identified the trigger, how does one solve the problem?  As I said at the beginning, this is extremely difficult, unless one has in fact pinned down the exact cause or combination of causes of the aggression.

Only then, can an experienced trainer design an appropriate intervention and desensitizing/ reconditioning programme. The bad news however is, that such programmes will require time and patience, plus, at the end of the day, there is little guarantee that the problem will be solved 100%.  Especially for older mature dogs. I have tried on many occasions, and seldom succeeded. I have the scars to prove it.  Not unless one reverts to an extreme intervention, such as “e collar” or similar device. Otherwise, one has to make do with the use of a muzzle on one’s dog, at least when in certain high risk environments.  

But, just a quick word about the impact of neutering and spaying on the level of aggression in dogs.  Once again, the jury seems to be out, with many conflicting opinions. Does a castration or hysterectomy change levels of aggression in humans?  Few claim that less oestrogen makes a female less aggressive, although some say “irritability” levels may sometimes increase.  In males however, there seems to be more support for the view that castration, resulting in the production of lower levels of testosterone, does appear to reduce levels of aggression in men. There appears to be a similar line of thinking about dogs.  I conclude therefore, that in dogs, neutering may well tend to reduce the desire to fight other dogs, but not necessarily so in bitches.  I say this, bearing in mind as discussed above, that there are numerous other triggers for aggressive behaviour in canines.

As the old saying goes, prevention is better than cure. Thus, it’s always best to select the right breed and socialise ones dog as much and as early in life as possible. Learn how to observe and read the dog’s body language and correct any undesired behaviour as it happens, before matters escalate.

Cheers John Cox

Nov 2022