According to local reports, the dog which was a pit bull had been rescued by the woman from the countryside a few days earlier, when she found him abandoned.
She had then taken the dog to her house in the province of Macastre, according to a statement by officials cited in Heraldo.
As per the Guardia civil the attack happened on February 24, when the emergency services received a call and rushed to her house.
When the emergency service arrived, the dog was still inside the house, so they could not attend to her immediately.
Shortly after two agents from the Civil Guard arrived, and one of them shot at the Pitbull so that the doctor could attend to the victim.
The woman was taken to the Hospital de la Fe as she suffered severe injuries to her head and arms.
According to medical sources cited in Las Provincias, the woman "entered into a state of shock after suffering a hemorrhage", but they had managed to stabilise her before taking her to the hospital.
She was then in the intensive care where the doctors tried to save her, but she died.
The Guardia Civil has said that an investigation is being conducted as they are trying to locate the owner of the pit bull, who had no identification microchip.
Who has no chip, the owner or the dog?