One can kill the black and other dogs if they are rapacious and harm people, otherwise not.
(1) They should not be killed needlessly.
(2) The cloth and body does not get impure if it is touched by dry pig and there is no impression of impurity. But, it the pig is wet, then it is necessary to wash the place which is affected by its wetness.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband