How can a house be purified if a dry dog touches wet surfaces, or if the impurity of dog saliva transfers from a dry surface to other wet surfaces?

It is not ruled that impurity is transferred from a dog except with certainty that its saliva has made contact. With doubt, the default is the absence of impurity. There is a difference of opinion among scholars regarding the transfer of impurity from the dog's saliva to wet objects, and it is permissible for the one afflicted with obsessive doubts to adopt the view that it does not transfer. The dog must be removed from the house unless there is a need for it; otherwise, the reward of its owner decreases by one qiraṭ every day.