Have used ceramic heat lamp in the past over just one side of the whelping box but found that the bitch gets overheated and this can sometimes lead to dehydration in puppies. Found a heat pad much better as pups can move away if too warm do not like the room to be too warm for mums sake but pups have to be kept warm as they can not regulate their own body temperature till 10 days old, I then start to reduce the heating slowly.