The Bull is still alive when it is dragged out
Every Matador’s third Banderillero (one of the members of a bullfighter’s "supporting band"in the ring) also functions as the puntillero.
Once the Matador has executed the so called moment of truth, the death trust, and the bull has collapsed onto the ground, it is the puntillero’s job to approach the bull and sever the bull’s spinal cord to ensure death. This is done with the puntilla, a broad bladed dagger, to ensure a quicker and painless death to the animal.
The misperception is borne out of the fact that muscles often continue to twitch post mortem, including the eyelids, which will give people unaware of this the impression, that the animal is still alive.