מילון על שבת 270:13

It shall stay seven days with its mother. In case the animal is non-viable. And further -- everything which separates from a place of impurity and a place of stench needs separation before it enters into the camp of God's Presence; according to this rule is the zav, the metzora, and the tamei meit [all of whom have an intermediate period after the cause of their impurity ceasing before they re-enter the camp of the Jewish people].