If your dog is exhibiting aggressive behavior, please seek professional assistance right away.
It will not go away on its own, and the longer aggression goes unchecked, the more difficult it is to rehabilitate the dog. Aggression is an attempt to cause physical injury to another being or intimidating another being with the threat of causing injury.
It is a serious matter that should be addressed at the first sign that something is wrong.
Aggression is not something dogs will "grow out of".
It is interesting to note that dogs do not enjoy being aggressive.
Electrical Stimulation of the Brain (ESB) studies show that, given a choice, animals will not choose to be aggressive.
Australian Shepherds are known for being smilers, along with several other breeds.
Just as not every show of teeth is a display of aggression, neither is every growl a display of aggression.
The dog pictured right is a harmless, smiling, goofy dog.
In humans, this manifests itself as anxiety, depression, or obsessive compulsive disorder.