Is a dog's place or kennel considered impure?

A previous fatwa mentioned that the preponderant opinion is the impurity of the dog in all its parts, and that the place where a dog resides is considered impure if one is certain or highly presumes that it has been touched by the dog's excrement or saliva. However, if one doubts whether a specific place has been touched by the dog's impurity, it does not become impure, because the default state is purity until impurity is proven with certainty.