
Definately only use electric heat pads, micro ones just arnt up to the job. You wouldnt want to risk chilled puppies, they cool far to quickly and arnt at a constant level.
If you are using a cardboard whelping box you could make an + mark with a stanley knife at the bottom of the back of the box. This way you can pass the plug and cable through it, close it the hole again once passed through and the pups/mum cant get the cable and chew it.
However this time round Im using a linkabord plastic box. So not sure how Im going to hide the cable, might have to make a hole in the base or something.
But yes, the electric pads are far better for the pups than the microwave ones