AnswerYes they are, but be careful of the voltage. I personally think it is a form of animal cruelty, especially on small animals like dogs. If you get one, make sure it is for large farm animals that can actually handle the shock.
AnswerMost beer companies have some sort of catch so it's not truly an instant win. Usually you have to but the beer and enter the contest. The exception is when beer has a free t-shirt or hat in the case. Bud Light has a competition going on right now.