I know wal-marts near me dont carry and heating pads that dont come with a auto shut-off. Walgreens by me had the ones with out the shutoff but they where out of the smaller size's that i needed at the time but the larger size will work with my boa tank so im grabbing one today. I suspect human heat pads W/O auto shut off will be a thing of the past real soon, to much liability to the CO that makes them.
Heck I would hate to explain to my home owners insurance agent what I was doing running a heat pad 24/7 if it were to go up in smoke.