(When my females whelp...) We use a regular, plug-in heating pad, tha does not have an "auto shut-off". I put the pad under the box (kennel), on one side of the box so that if your baby gets too warm they can move over to the other side. The heat does penetrate the box and the blankets inside and it provides a nice warm and cozy "corner". So, in one corner, under the box a regular heating pad from Target or Wallmart, on a medium setting and line inside the box with your blankets and do a feel test to see if it feels right to you. Adjust it as needed...enjoy
and good luck. I hope it helps her...
