Dogs fight for a number of different reasons but dominance, in one form or another, underlies much of this feuding. When a couple of unfamiliar dogs encounter each other there is a good deal of mutual investigation that occurs between the two dogs before either can fully relax in the other's presence. During this investigational stage, all five senses are utilized to gather information about the competition and a variable amount of posturing goes on as the dogs transmit their comfort level toward each other through the medium of body language.
If two easygoing dogs meet, there is rarely a problem. If one dog is clearly dominant over another, and the other dog accepts his dominance, again there is no real reason for concern. The more dominant dog transmits his status to the other by certain characteristic posturing and expressions. Perhaps the most well known signal is the dominant dog's stare. Other signals of dominance include tensing of muscles, erect ears, tail held at or above horizontal, and the head and neck held high. The approach of the dominant dog is often toward the other dog's flank, and upon reaching it, he may rest his chin upon the other dog's back almost daring him to react.
A clearly subordinate dog will defer to a show of force by averting his eyes, shrinking down to make himself small, holding his tail either low or tucked between his legs, and may even squat and urinate or roll over to expose his belly in extreme situations. At the instant the dominant dog has received the signal of deference, he immediately stops posturing and may start playing with the other dog.
Problems arise when two dogs of near equal dominant status meet and the true leader is not immediately apparent. In signaling dominance, dogs may stand parallel to each other, facing the opposite direction, each with his head resting on the other's rump and each with his tail raised like a flag. Next may come a low growl, lip lift, snap, or even bite. If neither dog concedes, a dogfight will ensue, and winner takes all.
In an entirely appropriate battle, the dog that eventually emerges as the dominant individual immediately accepts the underdog's concession. The dominant dog may laud his victory for a few seconds before strutting off but will usually not sustain or escalate his attack under these circumstances. Some dogs, however, are not savvy regarding canine etiquette and will continue to attack despite the other dog's obvious submission. Such dogs usually have a checkered history of improper socialization with other dogs or have had adverse experiences with similarly dysfunctional dogs in the past.
A dominant dog may behave well in the presence of nine out of ten other dogs because the others either defer or are even more dominant. Occasionally, however, such a dog will encounter another dog of almost identical dominance status and that's when the trouble begins. As two owners stand chatting, not paying much attention to their dogs, a fight may suddenly break out.
Of course, there are many different circumstances in which dominance aggression may be displayed; however, they usually fall into the same categories as dominance aggression directed towards people. The first is in protection of a valued object or person, the second is in response to another's challenging postures or gestures (or even frank attack), and finally there is space guarding and/or territoriality. The dog's mood and motivation have a lot to do with whether he reacts in a particular circumstance. Both internal and external factors determine the dog's final reaction. Two internal factors are sex hormones and the neurotransmitter serotonin. Internal Factors
When male or female sex hormone levels are high, aggression is more likely. When serotonin levels in the brain are high, aggression is less likely. Castrating a male dog eliminates the supply of testosterone from the testes, and testosterone levels fall to near zero within hours. At the same time, brain serotonin levels rise, because testosterone is suppressed by testosterone. The result: a less aggressive dog especially as far as inter-male dominance aggression is concerned. In fact, aggression between males is substantially reduced by castration in two out of three cases. But castration is no panacea, as the dog's temperament, residual maleness, and learning all have some bearing.
Another internal factor that influences aggression is the hormonal change that occurs following parturition. When a bitch has had puppies
, her aggression level, particularly when it comes to protection of her pups, will be raised. The elevation in aggression (so called maternal aggression) exactly parallels the rise and fall of the lactational hormone, prolactin.
One last internal factor that influences the propensity for dominance-related behaviors is elevation in catecholamines (the fight or flight hormones). Increases in these neurotransmitters lower the threshold for impulsivity and aggression. External Factors
External factors include the location of an encounter, the nature of the combatant, and the presence of people, other dogs, or certain chattels. Dominant dogs will guard their own space (space guarding), exhibit territorial displays of barking when another dog approaches them on their own patch, and will be more likely to be aggressive if the transgressor is of near equal dominance status. People and other dogs can influence a dominant dog's confidence and combativeness, but in the presence of strong leaders (either people or other dogs) aggression is less likely. Thus, for owners of dominant dogs, increased leadership via a "Nothing in Life is Free" leadership program is invaluable in helping curb the dog's dominance aggressive overtures towards other dogs.