How is that which a dog has licked purified if the father refuses to bring a dog for guarding based on its impermissibility?

Scholars have differed regarding the permissibility of keeping a dog for guarding the threshing floor (jarin) and what is in it. The fatwa issued is that it is permissible to keep it for the sake of benefit (maslaha). One is not required to perform ghusl (ritual bath) from a dog. Rather, what it licks or touches with its saliva must be purified by washing it seven times, one of them with earth or what takes its place, such as soap.