A tip… My strong advise is that a head of time/NOW is to get your self a couple of good anti venom kits, bring your dog to the vet and have the vet administer a shot to provide your dog some protection against the venom of rattlesnakes. (same with current rabies vaccines) It won...
then at least try to separate the victim from the live wire by using dry wood or rubber. Wrap the victim with warm blankets to prevent hypothermia [abnormally low body temperature], administer CPR [Cardio Pulmonary Resuscitation] and rush him/her to an hospital...