The thing to do is to subscribe to one of the agencies that you can gve details of the cards in advance, and then, if they go missing, you just phone them up. One phone call, and you are covered. (And if you've got some card where a phone call doesn't mean that as soon as you inform them no further charges can be made agains tyour account, you should promptly switch to a better credit card provider.)

Mind, this can backfire on you. I remember on a trip to Prague a friend thought she had had her wallet stolen, and made the cancel-everything call. Then she found her wallet, and had no way of cancelling the cancellation, and was completely without any kind of card until herc holiday was over.