We make a mistake if we interpret our dog's behavior exclusively through our own human filter. We can't judge it on the same terms we judge human behavior. We have to take a step back and understand it on its own terms. And even though dog-dog aggressive displays are undesirable, we need to keep our perspective. Let's take look at some of the reasons that dogs might display aggressive behaviors toward each other.
Fear is a defensive type of aggression. It occurs when a dog perceives his physical safety is threatened or when his critical distance is invaded. There is an imaginary line around your dog. If a perceived threat remains outside this line, your dog will be alert and watchful, yet calm. If a perceived threat crosses this line, however, the dog will start showing anxious defensive, or aggressive behaviors.
Fear seems to be a common, if not the most common, trigger of threats and aggression. Dogs displaying this type of aggression are often called fear biters. This behavior is associated with a combination of defensive and submissive body postures. For example, the dog may bare his teeth and air-snap, but at the same time his ears will be flattened and his tail tucked between his legs.
Fearfully aggressive animals will not generally chase their opponent or continue an attack once the opponent has retreated outside the critical distance.
This is a popular label for categorizing threats and aggression. And, like many fashionable labels, it is often misused. So make sure you are really describing how your dog behaves, and not just assuming that, because she's growled or lunged at another dog, it's a dominance behavior.
So what does this type of aggression look like? First of all, the dog's body language will be more offensive than defensive. Unlike fear-based aggression, her posture will be "up": her tail raised, her ears pricked.
Another important clue, in understanding dominance-type aggression, is what triggered it. Often the trigger is that another dog fails to display proper appeasement behaviors. It can also be triggered when another dog tries to make possession of a valued resource: a bone, a couch, a toy. It's important to understand that dominance is not a personality trait. It's not an emotion. It's not some trait that your dog might have that needs to be cured or controlled.
Dominance-related aggression is a reaction to a social situation. Period.
Possessive aggression occurs when a dog has a valued resource such as a bed, toy, or food, and she doesn't want to share. Some authorities combine this category with dominance aggression. It's also been described as territorial aggression, or guarding behavior, or resource guarding. Possessive aggression can be directed toward humans as well as other dogs. It may have offensive or defensive components, or a combination of both.
When a dog is defending one or more members of his social group, the behavior might be termed protective aggression. Some authorities include maternal aggression in this category. As with possessive aggression, protective aggression behaviors may include both offensive and defensive components.
Territorial aggression is shown when a dog is defending his home area or social group. It also may include offensive and defensive components.
If a dog is in physical pain or discomfort, she might respond by displaying defensive aggression. for this reason, it is important to be careful around any dog you believe might be in pain. If your dog is older and suddenly starts showing defensive aggression, it's always good to first rule out pain-related aggression as the cause. This is particularly important if the aggressive behavior is out of character for your dog. If this is the case, schedule a visit to the vet. Pain-related aggression is sometimes classified as fearful aggression. The positive side of pain-related aggression is that sometimes a trip to the vet is all you need to address it.
If a dog is prevented or blocked from attacking her primary target, that offensively or defensively motivated aggression can be directed toward any individual who is handy. This might be another dog or a person, including you.
Sometimes called pack-facilitated aggression, this category applies when one or more dogs in a group displays aggressive behavior and other dogs then join in. It's similar to other behaviors that seem to be inspired by nearby dogs, such as when one dog starts to bark or howl and pretty soon all other dogs around start barking and howling too.
Predatory behavior is sometimes listed as a form of aggression. Not everyone agrees with this, however. Predatory behavior is related to a dog's instinctive method of obtaining food. It is not displayed as a reaction to social conflicts. Instead, it is directed toward individuals or objects moving away from the dog. Joggers, bicyclists, and skate-boarders can stimulate predatory behavior. Dogs will also display predatory behavior toward small mammals such as cats, mice, and birds.
Some attacks on children are probably related to predatory behavior. The dog perceives the quick, jerky movements and high-pitched vocalizations of children as similar to behavior of prey animals. Stalking, chasing, and nipping at the legs or ankles are characteristics of predatory behavior. A Border Collie working a herd of sheep is engaging in the initial stage of predatory behavior.
Predatory behavior has nothing to do with malice. A fisherman doesn't hate the fish: he just want to catch it. Similarly with dogs, catching prey has nothing to do with a dog's emotion. It's entirely businesslike.
Occasionally predatory-related behaviors can come into play between two or more dogs. Some behaviorists call this predatory drift. The dogs are getting along fine, when suddenly something causes a heightened arousal level. This, in turn, triggers a response in which one dog regards the other as prey.