Is washing in an electric washing machine sufficient to purify clothes from the impurity of a dog, or is it necessary to wash them seven times, one of them with earth?

Clothes soiled by dog impurity must be washed seven times, one of them with soap or a substitute thereof. Washing them seven times in an automatic washing machine is sufficient. By analogy with the Hadith: "The purification of the vessel of one of you, if a dog licks in it, is to wash it seven times, the first of them with earth"; the dog's saliva is impure, and whatever it touches must be washed. The clothes washed with it all become pure if they are washed seven times, the first of them with earth or a substitute thereof.