don't zap him! - applying electricity to his body isn't going to get him through this any better, it will only hurt him. he's not as big as a human and can't take as much electricity as a human.
i don't know what the truth is here, but being afraid of water is a symptom of having rabies, and now your dog is showing that symptom. so... my guess is that this is a specific reaction to the rabies shot in particular. have you called your vet to see if he's ever seen this reaction before?
the only good part here is that you and your dog only have to go through this once. you can specify next time that they JUST do the rabies shot, just like you wanted done this time. next time you'll know not to leave the room, to stick around and make sure they only do what you want.
hopefully someone else can give suggestions here about what to do for his reaction this time, i'm sorry i don't know what to do for it. but... stop zapping him. let his body get over this by itself, hopefully someone else on curezone will have advice about what to do for this symptom.
when my pets have had their shots, i've had the vet give them a shot of antihistimine, which helped their alleric reactions. (that oughta give a clue that shots are bad for them...) but... i don't think this is an allergic reaction exactly, it sounds more like a specific reaction to the rabies injection.