Obviously, prevention is the key to success — oodles of early socialization and handling with people and frequent off-leash walks, play and socialization with other dogs. With all cases of aggression (regardless of cause), the first step is to determine whether or not the dog is actually dangerous. Being reactive is not the issue; all animals “react”, humans included. 

The essential question is: Do they cause physical harm? Dog bite incidents are objectively assessed on a 1–6 scale based on wound pathology. Dog fights are assessed by calculating the Fight:Bite Ratio. Most dog bites and dog fights cause little, if any, damage and so, the prognosis is excellent for a hasty resolution via speedy classical conditioning techniques and basic lure/reward training for control and focus. 

With severe damage though, the dog is dangerous, the prognosis for resolution is extremely poor and so rehabilitation should not be undertaken cavalierly, if at all.