Re: rat electro shock....
I saw a similar device at a zoo park in Spain. Its purpose is to keep large animals (lions and tigers) to pass through a gate where cars were allowed to pass. Several parralel wires were installed in the floor (the passing gate is approx. 4 meters in length) and between each nearby wires a current was supplied. For such small animals like rats, the current should be small, but I cannot give you exact value, you'll have to make some test. I would choose for a starting point a 1khz sinewave generator, somewhere at 80-100V peak to peak, with an adjustable current limiter. Start with 1mA limit and make some tests, increase it and observe where the animals begin to react.
/pisoiu