Sounds like who ever trained the dog was VERY heavy handed in disciplining the dog to the point that you have a fear biter.May be why he got rid ofit.All dogs are different in what they can take as punishment,you must evaluate the dog and adjust to the dog.I like the phrase "firm but gentle".As for the e collar, it's a good tool only if you KNOW HOW AND WHEN TO USE IT,leting someone use a collar on a dog without knowing how and when to use it is like leting a monkey play with a straight razor.