Never force animals to do things they are afraid of

Always avoid reprimanding them (no matter how frustrated/embarrassed/rushed/angry/annoyed you are!). Physical or psychological punishment (or threat thereof) will make things worse in many cases. Set them up for success, take patience next time to approach or explore the scary thing at their pace and pair it with high value treats from a very safe distance. In addition, work with a professional qualified in positive reinforcement and science based methods to help you through these steps so that you have a dog that copes much better later on. 
Read more: http://www.dogster.com/dog-training/dogs-and-fear-of-strangers
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