I know of no way to 'turn it off' temporarily. However there are programs out there that can lock your keyboard, until a specific key, or set of keys, is hit. Programs like say "Keyboard Locker". There are more, but that is the one that I remembered first.
Do a quick search and find one that meets your needs.
Just remember, that will resolve the cats making programs launch, act funny etc., but it won't keep the keyboard itself from being damaged by their walking/laying on it.