The process of Desensitization may take several days, weeks, or even months. Procede at a slow enough pace so your dog never becomes fearful during the process. If you move too quickly it will not be successful.
How to Use the Technique
Begin by exposing your dog to a very low level or small amount of whatever it is that's causing his fear. For example, if he is afraid of bicycles, start with a bicycle placed at a distance of 100 feet from your dog.
Reward him for calm, non-fearful behavior in the presence of the bicycle.
Gradually move the bicycle closer to him. As long as your dog remains relaxed, reward him with treats and praise.
If at any time he becomes anxious, move the bicycle further away and proceed at a slower pace.
When your dog can remain relaxed in the presence of a stationary bicycle, move the bicycle 100 feet away again, but have someone ride it slowly by him.
Again, gradually increase the proximity of the slowly moving bicycle, rewarding your dog for remaining calm and relaxed.
Repeat this procedure as many times as necessary, gradually increasing the speed of the moving bicycle.