Aggression in dogs is usually a normal canine behavior, i.e. in a dog's world a dog uses aggression to control situations. It is the fact that dogs are living in social contact with humans, that makes aggressive behavior unacceptable.

Dog aggression is a multifactorial phenonenon, which makes it difficult , if not meaningless, to predict aggressive behavior on a single characteristic, such as a dog's breed.

Among the factors associated with dog aggression are:
- the gender (70 to 90% are perpetuated by male dogs);
- place of origin of the puppy (dogs coming from pet stores and puppy mills have a higher incidence of dominance aggression, due to lack of socialization and imprinting)
- permissive or over-indulgent owners,
- an underlying medical condition
- traumatic experiences
- inherited predisposition toward fear linked to breeding lines (shepherding breeds and some toy breeds)

The  most frequently diagnosed type of aggression is dominance-related aggression, a type of aggression that may be encountered in all breeds.  While people immediately associate dominance with the so-called guard breeds, like Rottweilers and Dobermanns, other breeds like Cocker Spaniels and English Springer Spaniels are actually among the most common breeds diagnosed with dominance-related aggression. Smaller breeds like the Shih Tzu are, despite their size, also frequently found to be dominant and aggressive. In fact, whether small or large, no breed is really exempt from this characteristic.

Dominance related aggression occurs when the owner is unwilling or unable to maintain a dominant position in the pack. A dog considers its human family members as part of his pack, within which exists a well-defined leadership hierarchy. Problems occur when the owner is not easily identified and/or accepted by the dog as the leader (the "alpha") of the pack.

Owners do not always recognize the triggers for dog aggression. These triggers may be any situation or action by a human perceived by the dog as a challenge or as a violation of its high social rank, such as:
  • when the dog is protecting food or certain objects (toys, stolen objects)
  • when the dog is disturbed when sleeping
  • when the owner is trying to lead the dog by the collar
  • when the owner is disciplining the dog, etc.

Many cases of "dominance" aggression have an early onset. Many owners tolerate from puppies behavior that would be considered unacceptable and/or dangerous in an adult dog.

While dominant aggression may be found in all types of dog breeds and is usually directed towards the family members, the second most common aggression problem is fear aggression, which is usually displayed towards people outside the family. As we already said, this type of aggression is more common in breeds showing an inherited predisposition toward fear linked to breeding lines. Some dog breeds have a greater propensity toward developing a fearful temperament, such as the shepherding breeds and certain toy breeds. This predispositon is not usually found in the dog breeds that descend from ancient 'fighting dog breeds'. Indeed, these breeds were bred for centuries precisely for their fearfullness and courage and as a result may be considered as being less prone to exhibit fear-related aggressive behavior than other more stress-sensitive breeds.
Other possible causes of fear-based aggression include:
  • lack of socialization in early puppyhood, more precisely during the sensitive periode between five and 12 weeks of age. This is a very common cause of aggression. Poor socialization is often encountered in puppies bought from puppy mills and larger pet stores.
  • an event early in the puppy's life that may have traumatized the puppy.

How do you recognize the type of aggression a dog is exhibiting ?
As we already said, dominance aggression is usually oriented towards the members of the family (the persons who are more likely to challenge the dog's position within what he considers his "pack"). A dog displaying dominance-related aggressive behavior will appear confident (tail eract, ears held high) and moves forward to challenge his target, while eye contact is maintained. With fear aggression, on the contrary, the dog will look frightened and skulking (lowered head and body, ears down, tail curled under bottom), shifting eye contact and licking his lips, indicating unsureness. Fear aggression usually appears when facing people who are not part of the familiar "pack", i.e. people outside the family.
It is very important to distinguish between these two types of aggression because wrongly applied training methods may frighten fearful dogs even more, rather than teaching them anything.

Bad and dangerous behavior in dogs often results from lack of information or misinformation in their owners, AND their breeders. While breeders may deliberately or unknowingly breed unsound temperaments, prospective buyers and owners also bear a responsibility in that, they should be attentive as to where they buy their puppy and how they educate it. Read more about the responsibility of the prospective buyer and responsible dog ownership.

Dog Aggression
(Dominance Aggression, Fear Aggression)
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Aggression in Dogs:
Practical Management, Prevention & Behaviour Modification (Paperback)
by Brenda Aloff
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Related Pages
Related Books
Understanding & Handling Dog Aggression
by Barbara Sykes
More information:
Dog Aggression: Fighting (2004)
VHS tape
More information:
Dog Aggression: Biting (2004)
VHS tape
More information:
The Cautious Canine
(Paperback)by Patricia B. McConnell
More information:
Feisty Fido
(Paperback)by Patricia B. McConnell, Karen B. London
More information:
Books on dog aggression
Books on problem behavior in dogs

Responsibility of the prospective owner
Dog Supplies
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Dog breeds homepage
Guard dog breeds
Dog breeds Homepage
The Dominant Dog by Jacqui Neilson, DVM, Animal Behavior Clinic Portland, OR.
Breaking Bad Habits in Dogs by Colin Tennant, Expert Dog Trainer and Canine Behaviorist.