Is your dog reactive?  Mine was but he isn't anymore; having had a lifetime of experiences he rarely reacts ever now, in a reactive sense that is.  I remember trying to explain reactive to my pet sitter when Luke was young.  I told her first that he was a reactive dog and by the ????? look on her face I tried to explain.

Reactive simply means that a dogs over reacts to external stimuli.  They are typically highly aware dogs; the type that nothing gets past.    Some dogs have particular triggers; others are over reactive in general. The term reactive is descriptive; how reactive a dog is can range vastly. Luke was on the low end of reactive; I have seen highly reactive dogs and it is not fun.  Luke often had an aggressive response but was not actually aggressive.  An aggressive response is common in reactive dogs; learning to deal with the aggression take a great deal of education and care.  

Rehabilitating a reactive dog takes time and patience.  You must also educate yourself to your dog's specific triggers before you begin to work on the reaction itself.  Harsh training methods, ie. choke collar or pinch/prong collar type training has absolutely no place in working with a reactive dog.  It would be like taking a bottle of lighting fluid and throwing it on the fire.  Calm distance is the first step in helping a reactive dog.  Whatever the trigger might be, you must calmly move away.  You yourself must become very observant and have great situational awareness.  You cannot help your dog if you are also reactive so you first have to get a handle on your own emotions.

To change how your dog reacts to certain stimuli you must work at a distance around it.  You associate it with a nonchalant attitude and pair it with a positive association.  Under socializing is a big cause in a reactive dog.  Exposure is imperative to rehabilitation.   If you have a reactive dog you must address the situation as soon as possible.  Some reactive dogs are helped over time with exposure alone but many need extensive work.

Just because your dog reacts to certain things does not make them a reactive dog.  Reactive dogs are different and once you see one you will clearly understand the difference.  More in an article on my website in the near future.