It is necessary to begin with this: there are humans and there are animals. Some dogs can be with human soul. Usually they are fancy dogs such as dachshunds, yorkshires, chihuahuas. Pit bulls, rotweillers and boxers are, after all, animals. Satan is not human, he is animal and God displaces satans regularly, there are many of them. There is the most ancient satan ( he is a snake which developed into the human form ) and some of them are more young (sometimes bulldogs, sometimes fallen people etc.) If satan is with human soul, God makes the soul sleep. The mind works, but in fact it is not true human.
Why God doesn’t want to annihilate satan and we would live in the happy humanbeing? Satan controls the downer world. Thus God can see evil gods and annihlate them.