A dog licked my shoe, what should I do?

The saliva of a dog is impure (najis), and the spot it licks must be washed seven times, one of them with earth, until it is purified. This is based on the Prophet's (peace and blessings be upon him) saying: "If a dog drinks from the vessel of one of you, he must wash it seven times." Scholars differed on whether soap can substitute for earth, and the preponderant opinion is that it suffices if it achieves the intended purpose.