Is it permissible to raise a vaccinated dog for guarding purposes, and what is the ruling on its saliva or hair touching clothes or the body? Does that nullify ablution or defile clothes, and is it permissible to pray in a courtyard where a dog is present?

If a dog touches clothes with its wet fur or saliva, they must be washed seven times, one of them with earth. Prayer in a courtyard where there is a dog is valid if the ground is pure. However, if the ground is soiled by the dog's impurity, prayer in it is not valid until it is purified. Scholars have differed on the purification of impure ground. The Hanafis believe it is purified by the sun, wind, or dryness, while the Shafi'is and Hanbalis believe it is only purified by water. They also differed on the impurity of the dog to the ground; the Shafi'is believe it is obligatory to wash seven times without earth, while the Hanbalis believe that abundant water is sufficient. The most cautious approach is to act according to the Shafi'i school of thought.