Experienced breeders - What is your favorite method to keep a litter warm and prevent chilling. I have microwaveable heating discs http://snugglesafe.co.uk/heatpad.htm , but am starting to think I'll need better methods. I am thinking about an actual heating pad, but have heard horror stories about cooking puppies, I am also thinking about a heating lamp. Anyway, what do you use and do to prevent chilling of your litters?