All perfect praise be to Allah, The Lord of the Worlds. I testify that none is worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
Since you doubt the existence of impurity on that floor, then the basic principle is that it is non-existent. Moreover, the impurity of the dog on the floor is purified by pouring water over it. As long as that water that splashed on you was not changed (in color or smell), then it is ruled to be ritually pure even if we assume the existence of impurity on that floor.
Allah knows best.