Question:

If was ruled that if a dog licks on plate one has to washed it seven times, what about if it licks one cloth or body, how does one washes this away.

Answer:

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

It is an obligation to wash seven times, the first of which with soil, any
container, clothes or anything else, that is licked by a dog, or
touched with its urine or excrements, as the Prophet said: "If a dog licks a receptacle of yours, one should wash it (that receptacle) seven times, the first of which with soil." This applies to a receptacle or anything else as the impurity is the same, which is the saliva of the dog, and its urine and excrements are worse than its saliva.

As regards how to purify a cloth which is licked by a dog, then if the
cloth will not be damaged by the soil, then the first wash should be
with soil mixed with some water so that the soil will reach the entire
place touched by the impurity, and one should rub it and then wash it
with water the second, third until the seventh time. It is not sufficient for the first wash to just put some soil on the cloth and then remove it with water (one must rub it). However, if the cloth
could be damaged with the use of soil, then one may put a little bit of
soil. Many jurists stated that soap and other cleaning substances take the place of soil. This is the summary of what the jurists mentioned about the method of removing the impurity of a dog.

Source: islamweb.net