What is the ruling on shaking hands with a dog breeder, knowing that he does not purify himself seven times, one of them with earth, after touching a dog, and is this considered from the perspective of purity?

Touching a dog with a dry hand on a dry part of its body does not necessitate ritual purification. Rather, purification is required only for what is touched by its saliva, the wetness of its mouth, or its body moistened with its saliva, by washing it seven times, one of them with earth. The Malikis are of the view that a dog is not impure.