Our dog used to use the cat box in extreme cold events up north. I do not normally approve of this activity because the dog searches for "kitty box crunchies" while using the box (not to mention the cat gets REALLY miffed at someone using her box)

Thankfully, it never gets that cold down here, although I did have to scrape ice off the windshield of my car this morning (not really ice, probably just heavy frost, but STILL this is SW FL for pete's sake!)