Aggressive/dominance and communication
Aggression and dominance are commonly intertwined; but they are very different in the dog world. Dominance became a very "in" word several years back and people were throwing it around like "positive training." I actually had to stop using it for a longtime because it evoked fear in many people.
Dominance is a state of being; in dogs you have dominant and submissive with more or less of each state in each individual dog. Dogs are pack animals and being pack animals some lead and some follow. If all dogs were leaders then there would be a big problem. Dominance has nothing to do with aggression; aggression stands on its own. I have added dictionary meanings to explain both terms below.
The term "aggressive"
characterized by or tending toward unprovoked offensives, attacks, invasions, or the like; militantly forward or menacing
The term "dominant"
ruling, or controlling; having or exerting authority or influence: dominant in the chain of command, occupying or being in a commanding or elevated position.
A dog does not need to be a dominant dog to display aggression. Any dog can be aggressive for many reasons. Probably the most common form of aggression is dominance; dominance towards the guardian and family. This is not a true dominant dog problem but one where humans allow a dog who may not normally be a dominant dog to become dominant. Many dogs who are dominant aggressive are not truly a dominant dog but have been forced to take the dominant poisition within a household. Guardians who do not lead their dog risk this scenario.
I have met many dogs with aggression problems caused by lack of leadership. Some of the worst cases have been the little dogs; the type that get away with murder only because people think they cannot inflict as much harm. True on one hand; a Great Dane bite will probably do more damage than a Yorkie bite. But on the other; a small dog can inflict severe life threatening bites. Many children have been scared for life by a small dog. Size should not matter when aggression is the route problem.
When dogs meet onleash or off there is often aggressive communication. Many people will step back and state "oh, your dog is aggressive." This is wrong in most cases; dogs need to communicate and their means of communication is with their body and sound. They can't walk up and say "hey my name is Bob; I'm a bigwig at a big company and I have an expensive car." So their way of saying this is to stand on their toes and look the part.
If another dog comes by who doesn't know about this big headed dog; they soon will. The problem lies mostly with humans, rarely dogs. Typically other dogs will just let the hot aired dog posture around; not getting in his way. But many guardians take great offense to any communications from other dogs to theirs. It is all in what the body is saying.
Take Luke for example; a very good example I might say. When we go to the vet he displays very aggressively; growling very deeply and trying to look very menancing. To people who do not know him; they want to grab a muzzle. But I know my dog and know that he has never even attempted to bite someone. The fact that he stays back and only does the tiniest of mock charges tells you alot. And what the person does after this tells everything; if they ignore the behavior and sit down on the ground it ceases. The behavior is fear based; Luke tries to keep people away from him at the vets by seemingly being big and scarey.
Now of course not all dogs are bluffing; fear can be a very scarey behavior. Fear must be dealt with very carefully; especially if a fearful dog's reaction to a fearful situation is aggression. You cannot punish fear; you must teach a dog to be confident and help them to get over or at least deal with their fears.
Dominance on the other hand is a state of being; wanting to be a leader type, a take charge type of dog. My Jack Russell Jessie is very dominant; but in our pack she is a very calm and level headed leader. Luke is a very dominant dog as well; but being that he is not level headed and is not a calm type dog I do not allow him to become the top dog. He basically is a wanna be; he tries very hard, postures around but lacks the big boy confidence and stability to be a real leader.
Just lastnight he attempted to mount Tilley; strictly for dominance sake. Lacking confidence he tries this when Tilley is vulnerable, half up on the couch. It takes but a second for her to retaliate; and he runs for cover. Tilley is very confident but not a dominant dog at all; she is just happy being and has no hidden agenda.
Dogs are very simple yet very complicated.